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, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230408001
Abstract:
First, polyacrylonitrile/polyvinyl pyrrolidone (PAN/PVP) fibrous membrane was prepared by electrospinning, and then polyacrylonitrile porous (PPAN) fibrous membrane was obtained by water impregnation. Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) were used to explore the mechanism of fiber pore-forming, and X-ray photoelectron spectroscopy (XPS) was used to study the interaction between PAN and PVP molecules in the porous fibrous membrane. At the same time, the effects of mass ratio of PAN to PVP on the morphology, surface area, wettability, mechanical properties, and oil/water separation performance of porous fibrous membrane were investigated, and the optimal mass ratio was determined. When m(PAN)/m(PVP) was 1∶2, PPAN fibrous membrane showed higher mechanical properties. The separation flux of the n-hexane/water mixture was (46318 ± 3879) L/(m2·h·bar), and the efficiency was (96.01 ± 0.38)%. It also realized the efficient separation of different kinds of oil/water mixtures. In addition, PPAN fibrous membrane showed excellent cyclic separation performance, and the flux loss rate was only 8.9% after ten cycles of separation.
First, polyacrylonitrile/polyvinyl pyrrolidone (PAN/PVP) fibrous membrane was prepared by electrospinning, and then polyacrylonitrile porous (PPAN) fibrous membrane was obtained by water impregnation. Fourier transform infrared (FT-IR) spectra and thermogravimetric analysis (TGA) were used to explore the mechanism of fiber pore-forming, and X-ray photoelectron spectroscopy (XPS) was used to study the interaction between PAN and PVP molecules in the porous fibrous membrane. At the same time, the effects of mass ratio of PAN to PVP on the morphology, surface area, wettability, mechanical properties, and oil/water separation performance of porous fibrous membrane were investigated, and the optimal mass ratio was determined. When m(PAN)/m(PVP) was 1∶2, PPAN fibrous membrane showed higher mechanical properties. The separation flux of the n-hexane/water mixture was (46318 ± 3879) L/(m2·h·bar), and the efficiency was (96.01 ± 0.38)%. It also realized the efficient separation of different kinds of oil/water mixtures. In addition, PPAN fibrous membrane showed excellent cyclic separation performance, and the flux loss rate was only 8.9% after ten cycles of separation.
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, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230413002
Abstract:
Hybrid microbial fuel cells integrating different technologies and applications are becoming one of the effective ways to break the power density limitation of microbial fuel cells in recent years. However, the typical hybrid microbial fuel cell technology is complicated to manufacture and limited by various conditions, which is not conducive to its realization for large scale applications. Herein, a three-dimensional iron foam anode coated by nitrogen-doped graphene (N-rGO/IF) was prepared by impregnation and high-temperature reduction, which has a large specific surface area three-dimensional structure. Thanks to the super hydrophilic nature of nitrogen-doped graphene (static water contact angle of 0°), the N-rGO/IF anode has good biocompatibility for high-density microbial loading (1534 μg/cm2). In addition, based on the iron foam substrate, the galvanic cell is successfully integrated into a microbial fuel cell device to construct a hybrid microbial fuel cell. This hybrid microbial fuel cell is simple to fabricate and has no condition limitations. The electrochemical test results show that this hybrid microbial fuel cell achieves a maximum power density of 0.6019 mW/cm2 with the enhancement of the galvanic cell (0.3585 mW/cm2).The results indicate that N-rGO/IF composite anode can be used for the design and fabrication of high-power hybrid microbial fuel cells.
Hybrid microbial fuel cells integrating different technologies and applications are becoming one of the effective ways to break the power density limitation of microbial fuel cells in recent years. However, the typical hybrid microbial fuel cell technology is complicated to manufacture and limited by various conditions, which is not conducive to its realization for large scale applications. Herein, a three-dimensional iron foam anode coated by nitrogen-doped graphene (N-rGO/IF) was prepared by impregnation and high-temperature reduction, which has a large specific surface area three-dimensional structure. Thanks to the super hydrophilic nature of nitrogen-doped graphene (static water contact angle of 0°), the N-rGO/IF anode has good biocompatibility for high-density microbial loading (1534 μg/cm2). In addition, based on the iron foam substrate, the galvanic cell is successfully integrated into a microbial fuel cell device to construct a hybrid microbial fuel cell. This hybrid microbial fuel cell is simple to fabricate and has no condition limitations. The electrochemical test results show that this hybrid microbial fuel cell achieves a maximum power density of 0.6019 mW/cm2 with the enhancement of the galvanic cell (0.3585 mW/cm2).The results indicate that N-rGO/IF composite anode can be used for the design and fabrication of high-power hybrid microbial fuel cells.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230309001
Abstract:
Carbon nanotube catalysts encapsulating cobalt-iron (CoFe) alloy nanoparticles (CoFe@Cs) were synthesized by calcination of cobalt-iron bimetallic Prussian Blue analogs (CoFe PBA), and further assembled on polyethersulfone (PES) membrane support by vacuum filtration to prepare composite catalytic membranes for catalytic activation of peroxymonosulfate (PMS) and efficient degradation of tetracycline (TC). The morphology and structure of the samples were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the composition was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Based on the morphology, composition, and performance, carbon nanotube catalysts (CoFe@Cs-900) were selected from the prepared series of CoFe@Cs, and further the reactive oxygen species (ROS) in the catalytic process was analyzed by reactive oxygen quenching experiments and electron paramagnetic resonance (EPR). The stability of the carbon nanotube catalytic membrane under long-term operation was tested under optimized conditions. The results showed that the calcination temperature played an important role in regulating the morphology and composition of the catalysts. Among them, the carbon nanotube catalyst prepared by calcination at 900 °C can produce the reactive oxygen species, including sulfate radicals (·SO4-) and singlet oxygen (1O2), for the rapid removal of tetracycline. The carbon nanotube catalytic membrane achieved more than 99% removal of TC in continuous 24 h cross-flow filtration, and the water flux was maintained at 172 L/(m2·h). Overall, the catalytic membrane showed excellent degradation performances and potential application.
Carbon nanotube catalysts encapsulating cobalt-iron (CoFe) alloy nanoparticles (CoFe@Cs) were synthesized by calcination of cobalt-iron bimetallic Prussian Blue analogs (CoFe PBA), and further assembled on polyethersulfone (PES) membrane support by vacuum filtration to prepare composite catalytic membranes for catalytic activation of peroxymonosulfate (PMS) and efficient degradation of tetracycline (TC). The morphology and structure of the samples were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the composition was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Based on the morphology, composition, and performance, carbon nanotube catalysts (CoFe@Cs-900) were selected from the prepared series of CoFe@Cs, and further the reactive oxygen species (ROS) in the catalytic process was analyzed by reactive oxygen quenching experiments and electron paramagnetic resonance (EPR). The stability of the carbon nanotube catalytic membrane under long-term operation was tested under optimized conditions. The results showed that the calcination temperature played an important role in regulating the morphology and composition of the catalysts. Among them, the carbon nanotube catalyst prepared by calcination at 900 °C can produce the reactive oxygen species, including sulfate radicals (·SO4-) and singlet oxygen (1O2), for the rapid removal of tetracycline. The carbon nanotube catalytic membrane achieved more than 99% removal of TC in continuous 24 h cross-flow filtration, and the water flux was maintained at 172 L/(m2·h). Overall, the catalytic membrane showed excellent degradation performances and potential application.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230222001
Abstract:
In the past two decades, solution-processed preparation of native heterojunction organic solar cells (BHJ-OSCs) have developed rapidly, and their energy conversion efficiency (PCE) has exceeded 19%, but the relatively large energy loss (Eloss) of the devices has become a bottleneck factor limiting their photovoltaic performance. Therefore, further improving the PCE of OSCs by reducing the energy loss has become the focus of research in this field. By analyzing the photophysical processes in OSCs, the mechanisms of different energy loss pathways are discussed, and the following four strategies are reviewed: (1) reducing the energy offset between donors and acceptors, (2) reducing the energy disorder, (3) improving the luminescence efficiency of the devices, and (4) reducing the reorganization energy. This paper systematically summarizes the recent progress in reducing the Eloss of non-fullerene OSCs systems, which provides an important reference for further improvement of the performance of such devices.
In the past two decades, solution-processed preparation of native heterojunction organic solar cells (BHJ-OSCs) have developed rapidly, and their energy conversion efficiency (PCE) has exceeded 19%, but the relatively large energy loss (Eloss) of the devices has become a bottleneck factor limiting their photovoltaic performance. Therefore, further improving the PCE of OSCs by reducing the energy loss has become the focus of research in this field. By analyzing the photophysical processes in OSCs, the mechanisms of different energy loss pathways are discussed, and the following four strategies are reviewed: (1) reducing the energy offset between donors and acceptors, (2) reducing the energy disorder, (3) improving the luminescence efficiency of the devices, and (4) reducing the reorganization energy. This paper systematically summarizes the recent progress in reducing the Eloss of non-fullerene OSCs systems, which provides an important reference for further improvement of the performance of such devices.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230322001
Abstract:
The organic semiconductor poly(3-hexylthiophene) (P3HT) film prepared by the spin-coating method is optimized by dichlorobenzene (o-DCB) solvent added with chloroform (CF). The organic electrochemical transistor (OECT) is obtained using the optimized P3HT film as the channel layer and ion gel as the electrolyte layer. The effect of CF on the roughness and molecular order of P3HT film has been inverstigated by atomic force microscopy, UV-visible spectroscopy and Raman spectroscopy. The effect of CF optimization on the electrical properties of the material is studied with a semiconductor parametic analyzer. Results show that CF introduction reduces the roughness of P3HT film and improves the order degree of P3HT molecular arrangement. The CF-optimized OECT exhibits significant synaptic excitatory pulse current characteristics under the stimulation of −0.5 V and −1 V electric pulses. Compared to the device without CF optimization, the amplitude of conductance regulation is increased by about twice and 16 times, respectively, along with the improved retention performance. The simulation results show that the accuracy of the neural network based on the CF-optimized OECT in recognizing MNIST（Modified National Institute of Standards and Technology） handwritten digits is increased from 73.6% to 92.7%. This device is expected to play an important role in large-scale neuromorphic computing applications.
The organic semiconductor poly(3-hexylthiophene) (P3HT) film prepared by the spin-coating method is optimized by dichlorobenzene (o-DCB) solvent added with chloroform (CF). The organic electrochemical transistor (OECT) is obtained using the optimized P3HT film as the channel layer and ion gel as the electrolyte layer. The effect of CF on the roughness and molecular order of P3HT film has been inverstigated by atomic force microscopy, UV-visible spectroscopy and Raman spectroscopy. The effect of CF optimization on the electrical properties of the material is studied with a semiconductor parametic analyzer. Results show that CF introduction reduces the roughness of P3HT film and improves the order degree of P3HT molecular arrangement. The CF-optimized OECT exhibits significant synaptic excitatory pulse current characteristics under the stimulation of −0.5 V and −1 V electric pulses. Compared to the device without CF optimization, the amplitude of conductance regulation is increased by about twice and 16 times, respectively, along with the improved retention performance. The simulation results show that the accuracy of the neural network based on the CF-optimized OECT in recognizing MNIST（Modified National Institute of Standards and Technology） handwritten digits is increased from 73.6% to 92.7%. This device is expected to play an important role in large-scale neuromorphic computing applications.
Stabilization of Pickering Emulsion by Terpolymer Microspheres and Application of Immobilized Enzyme
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230208001
Abstract:
Through self-stable precipitation polymerization, styrene (St), maleic anhydride (MA), and glycidyl methacrylate (GMA) were copolymerized to obtain nanoparticles with regular morphology and uniform particle size. This one-pot method has no stabilizer and emulsifier, and requires no stirring. The post-treatment is simple, and the product can be obtained only by centrifugation. The effects of monomer feed ratio and solvent on the morphology and chemical composition of nanoparticles were studied by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The prepared nanoparticles can be used as emulsifiers to stabilize Pickering emulsion and immobilize lipase through epoxy groups. It was verified that lipase was anchored on the oil-water interface by immobilizing on the particles. The influence of the contact angle of particles and the solvent volume ratio of n-Heptane to water (RO/W) on the emulsion size was observed by fluorescence microscope. With the increase of contact angle and RO/W, the emulsion size decreases, which is also beneficial to the enzymatic reaction. The effects of nanoparticle mass content, lipase concentration, Ro/w on the size of Pickering emulsion and subsequent enzyme catalyzed reaction were investigated. Results showed that when n(GMA)∶n(St)∶n(MA) is 2∶1∶1, the mass content of nanoparticles was 0.5%, the mass concentration of lipase was 3 mg/mL, and RO/W was 5∶5, the specific activity of immobilized enzyme was the highest, up to 7.5 times that of free enzyme, and it showed excellent reusability.
Through self-stable precipitation polymerization, styrene (St), maleic anhydride (MA), and glycidyl methacrylate (GMA) were copolymerized to obtain nanoparticles with regular morphology and uniform particle size. This one-pot method has no stabilizer and emulsifier, and requires no stirring. The post-treatment is simple, and the product can be obtained only by centrifugation. The effects of monomer feed ratio and solvent on the morphology and chemical composition of nanoparticles were studied by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The prepared nanoparticles can be used as emulsifiers to stabilize Pickering emulsion and immobilize lipase through epoxy groups. It was verified that lipase was anchored on the oil-water interface by immobilizing on the particles. The influence of the contact angle of particles and the solvent volume ratio of n-Heptane to water (RO/W) on the emulsion size was observed by fluorescence microscope. With the increase of contact angle and RO/W, the emulsion size decreases, which is also beneficial to the enzymatic reaction. The effects of nanoparticle mass content, lipase concentration, Ro/w on the size of Pickering emulsion and subsequent enzyme catalyzed reaction were investigated. Results showed that when n(GMA)∶n(St)∶n(MA) is 2∶1∶1, the mass content of nanoparticles was 0.5%, the mass concentration of lipase was 3 mg/mL, and RO/W was 5∶5, the specific activity of immobilized enzyme was the highest, up to 7.5 times that of free enzyme, and it showed excellent reusability.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230321001
Abstract:
Combined with template molecular pre-positioning, surface imprinting method, and post-modification strategy, a molecularly imprinted surface plasmon resonance (SPR) sensor was constructed on a gold substrate and used for detection of β-lactoglobulin (BLG) in camel milk powder. Firstly, the template molecule BLG was fixed by polyacrylic acid (PAA) on the gold substrate which was modified by polydopamine in advance. Then imprinting was performed using dopamine as functional monomer and crosslinking agent. Finally, partially hydrolyzed poly (2-methyl-2-oxazoline) (PMOXA-EI) with anti-protein adsorption function was grafted on the non-imprinted part, and the BLG molecularly imprinted SPR sensor was prepared after eluting the template. The changes of sensor’s surface hydrophilicity/hydrophobicity were studied by water contact angle (WCA) and the characterization of created sensor was performed by using Fourier transform infrared spectrometer (FT-IR), atomic force microscopy (AFM), and variable angle spectroscopy ellipsometry (VASE), respectively. Results show that the sensor performe a good linear relationship in the range of 0.21～10 μg/mL for BLG, and the detection of limit is 0.12 μg/mL. The sensor could detect the BLG in camel milk powder quickly and sensitively with a recovery rate between 100.2% and 100.7%.
Combined with template molecular pre-positioning, surface imprinting method, and post-modification strategy, a molecularly imprinted surface plasmon resonance (SPR) sensor was constructed on a gold substrate and used for detection of β-lactoglobulin (BLG) in camel milk powder. Firstly, the template molecule BLG was fixed by polyacrylic acid (PAA) on the gold substrate which was modified by polydopamine in advance. Then imprinting was performed using dopamine as functional monomer and crosslinking agent. Finally, partially hydrolyzed poly (2-methyl-2-oxazoline) (PMOXA-EI) with anti-protein adsorption function was grafted on the non-imprinted part, and the BLG molecularly imprinted SPR sensor was prepared after eluting the template. The changes of sensor’s surface hydrophilicity/hydrophobicity were studied by water contact angle (WCA) and the characterization of created sensor was performed by using Fourier transform infrared spectrometer (FT-IR), atomic force microscopy (AFM), and variable angle spectroscopy ellipsometry (VASE), respectively. Results show that the sensor performe a good linear relationship in the range of 0.21～10 μg/mL for BLG, and the detection of limit is 0.12 μg/mL. The sensor could detect the BLG in camel milk powder quickly and sensitively with a recovery rate between 100.2% and 100.7%.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230116001
Abstract:
The nucleation-elongation cooperative mechanism, as widely adopted by natural systems such as microtubules and actin filaments, exhibits superior properties for supramolecular systems in comparison to the isodesmic mechanism by avoiding the formation of short-ranged oligomers. In this study, a novel type of artificial supramolecular polymers with the nucleation-elongation mechanism have been constructed, by incorporating hydrogen bonding recognition motifs adjacent to the cyanostilbene core. It facilitates the combination of hydrogen bonds and π-π stacking interactions between the neighboring monomers in a synergistic manner. The different hydrogen bonding units (urea versus amide) exert crucial impacts on the supramolecular polymerization behaviors, which can be qualified by the thermodynamic parameters of the self-assembly processes. Furthermore, supramolecular polymerization imparts confinement effect to the cyanostilbene unit, giving rise to the specific formation of [2+2] cycloaddition products under 430 nm photo-irradiation. It is in stark contrast to that in the monomeric state, which undergoes Z/E photoisomerization reactions under the same conditions. Overall, the current study provides new insights to modulate multi-path photochemical reactions in a precise manner.
The nucleation-elongation cooperative mechanism, as widely adopted by natural systems such as microtubules and actin filaments, exhibits superior properties for supramolecular systems in comparison to the isodesmic mechanism by avoiding the formation of short-ranged oligomers. In this study, a novel type of artificial supramolecular polymers with the nucleation-elongation mechanism have been constructed, by incorporating hydrogen bonding recognition motifs adjacent to the cyanostilbene core. It facilitates the combination of hydrogen bonds and π-π stacking interactions between the neighboring monomers in a synergistic manner. The different hydrogen bonding units (urea versus amide) exert crucial impacts on the supramolecular polymerization behaviors, which can be qualified by the thermodynamic parameters of the self-assembly processes. Furthermore, supramolecular polymerization imparts confinement effect to the cyanostilbene unit, giving rise to the specific formation of [2+2] cycloaddition products under 430 nm photo-irradiation. It is in stark contrast to that in the monomeric state, which undergoes Z/E photoisomerization reactions under the same conditions. Overall, the current study provides new insights to modulate multi-path photochemical reactions in a precise manner.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221231002
Abstract:
Vinylcyclopropane (VCP), one of the most important cyclic monomers, features a highlystrained three-member ring bearing high strain energy, which leads to feasible 1,5-ring-opening process and other transformations under radical conditions, producing polymers with complex chemical structures including the 2-pentenyl repeat unit. Poly(vinylcyclopropane) (PVCP) often exhibits minimal volume shrinkage even volume expansion and can be used as excellent restorative materials with potential clinical applications. In fact, the free radical polymerization technique facilitates rapid and high-yielding polymerizations of a wealth of VCP monomers with diverse chemical structures, affording corresponding high molecular weight polymers, albeit with uncontrolled mixed repeat units. To selectively access the microstructures of PVCP, the merge of VCP chemistry and modern synthetic strategies, including atom transfer radical polymerization and visible-light photoredox catalysis, have extended the radical ring-opening polymerization (rROP) of VCP to new domains. This review provides a comprehensive overview of the development of the rROP for VCP, focusing on monomer design, strategies to tailor the polymeric structures, and the structure-property relationship. In closing, we offer our perspective on its future development based on the challenges still facing the rROP of VCP.
Vinylcyclopropane (VCP), one of the most important cyclic monomers, features a highlystrained three-member ring bearing high strain energy, which leads to feasible 1,5-ring-opening process and other transformations under radical conditions, producing polymers with complex chemical structures including the 2-pentenyl repeat unit. Poly(vinylcyclopropane) (PVCP) often exhibits minimal volume shrinkage even volume expansion and can be used as excellent restorative materials with potential clinical applications. In fact, the free radical polymerization technique facilitates rapid and high-yielding polymerizations of a wealth of VCP monomers with diverse chemical structures, affording corresponding high molecular weight polymers, albeit with uncontrolled mixed repeat units. To selectively access the microstructures of PVCP, the merge of VCP chemistry and modern synthetic strategies, including atom transfer radical polymerization and visible-light photoredox catalysis, have extended the radical ring-opening polymerization (rROP) of VCP to new domains. This review provides a comprehensive overview of the development of the rROP for VCP, focusing on monomer design, strategies to tailor the polymeric structures, and the structure-property relationship. In closing, we offer our perspective on its future development based on the challenges still facing the rROP of VCP.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221128002
Abstract:
The use of RNA interference (RNAi) is becoming a routine method of scientific discovery and treatment of human diseases. However, its application is hindered by adverse effects, especially the off-target effects. In this work, we established an shRNA test platform based on the plasmid to test the silencing ability of short hairpin RNA (shRNA) targeting survivin gene designed according to shRNA online software and then screened out two shRNAs with excellent silencing ability. The off-target effects were measured by testing the silencing ability of two selected shRNAs against targets with single-nucleotide mutations at different locations. Based on our understanding of the 3' tail function of microRNA (miRNA) and small interfering RNA (siRNA), we propose a method to reduce the off-target effect of short hairpin RNA by shortening the complementary length of the 3' tail and target sequence of siRNA only. This method can reduce the off-target effect of shRNA without damaging the silencing efficiency of shRNA gene, so as to effectively improve the specificity of shRNA gene silencing. Compared to previous studies of the weak base pairing of “seed” and 3' regions to reduce the off-target effect, our method is simpler and more efficient, without being limited by the sequence of 3' regions of the antisense strand. This method of reducing the off-target effects provides new ideas for the design of shRNA and siRNA, simplifies the sequence restriction in the design of shRNA and siRNA drugs to a certain extent, and broadens their use and prospects as therapeutic and diagnostic tools in medical treatment.
The use of RNA interference (RNAi) is becoming a routine method of scientific discovery and treatment of human diseases. However, its application is hindered by adverse effects, especially the off-target effects. In this work, we established an shRNA test platform based on the plasmid to test the silencing ability of short hairpin RNA (shRNA) targeting survivin gene designed according to shRNA online software and then screened out two shRNAs with excellent silencing ability. The off-target effects were measured by testing the silencing ability of two selected shRNAs against targets with single-nucleotide mutations at different locations. Based on our understanding of the 3' tail function of microRNA (miRNA) and small interfering RNA (siRNA), we propose a method to reduce the off-target effect of short hairpin RNA by shortening the complementary length of the 3' tail and target sequence of siRNA only. This method can reduce the off-target effect of shRNA without damaging the silencing efficiency of shRNA gene, so as to effectively improve the specificity of shRNA gene silencing. Compared to previous studies of the weak base pairing of “seed” and 3' regions to reduce the off-target effect, our method is simpler and more efficient, without being limited by the sequence of 3' regions of the antisense strand. This method of reducing the off-target effects provides new ideas for the design of shRNA and siRNA, simplifies the sequence restriction in the design of shRNA and siRNA drugs to a certain extent, and broadens their use and prospects as therapeutic and diagnostic tools in medical treatment.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221229001
Abstract:
Hydrogel is a kind of polymer network swelling in water, which has structural similarity with biotissues. Traditional hydrogels are mechanically weak and brittle, due to their inherent heterogeneous microstructures and high water contents, which severely limit their applications. In recent years, researchers have been committed to improving the mechanical properties of hydrogels and have developed many strong and tough hydrogels, such as double-network (DN) hydrogels, dynamic bond hydrogels, hydrogels with rich entanglements, and fiber reinforced soft composites. In this review, we first summarize the development of hydrogels for enhancing mechanical properties and then introduce the relationship between stiffness and toughness of hydrogels. After that, several typical tough and strong hydrogels are selected to introduce their deformation and fracture behaviors, which give a preliminary understanding of the energy dissipation mechanisms of different hydrogels. The mechanisms mentioned in this paper include the breakage and reformation of physical bonds, the enhanced crack resistance due to phase-separated structure, the bulk viscoelastic energy dissipation, the near-crack dissipation and the fiber pullout and rupture. Then, the characteristics of these strong and tough hydrogels are summarized as follows: DN hydrogels dissipate energy through chain scission but soften after large deformation; dynamic bond hydrogels show self-healing behavior and large bulk hysteresis; hydrogels with rich entanglements have dense entanglements but sparse cross-links and low hysteresis; fiber reinforced soft composites have multi-scale energy dissipation and very large process zones.
Hydrogel is a kind of polymer network swelling in water, which has structural similarity with biotissues. Traditional hydrogels are mechanically weak and brittle, due to their inherent heterogeneous microstructures and high water contents, which severely limit their applications. In recent years, researchers have been committed to improving the mechanical properties of hydrogels and have developed many strong and tough hydrogels, such as double-network (DN) hydrogels, dynamic bond hydrogels, hydrogels with rich entanglements, and fiber reinforced soft composites. In this review, we first summarize the development of hydrogels for enhancing mechanical properties and then introduce the relationship between stiffness and toughness of hydrogels. After that, several typical tough and strong hydrogels are selected to introduce their deformation and fracture behaviors, which give a preliminary understanding of the energy dissipation mechanisms of different hydrogels. The mechanisms mentioned in this paper include the breakage and reformation of physical bonds, the enhanced crack resistance due to phase-separated structure, the bulk viscoelastic energy dissipation, the near-crack dissipation and the fiber pullout and rupture. Then, the characteristics of these strong and tough hydrogels are summarized as follows: DN hydrogels dissipate energy through chain scission but soften after large deformation; dynamic bond hydrogels show self-healing behavior and large bulk hysteresis; hydrogels with rich entanglements have dense entanglements but sparse cross-links and low hysteresis; fiber reinforced soft composites have multi-scale energy dissipation and very large process zones.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221107002
Abstract:
A reversible adhesive PAzo-PEG, with a main chain structure of methyl methacrylate and a side chain of azobenzene(Azo) having six methylene spacer groups and a short polyethylene glycol(PEG) chain as a tail group, can undergo solid to liquid transformation under UV and visible light irradiation. It was prepared by atom transfer radical polymerization (ATRP) the azobenzene group undergoes reversible trans-to-cis isomerization under UV and visible light irradiation, and the process is reversible. The reversible photoisomerization process of solid materials was studied by UV-Vis absorption spectroscopy. The solid-to-liquid transition was studied by differential scanning calorimetry (DSC). Results showed that the solid-liquid transition is due to the different glass transition temperatures (Tg) of the cis and trans isomers, and Tg of trans is higher than room temperature while Tg of cis is lower than room temperature, so PAzo-PEG macroscopically exhibits reversible solid-to-liquid transition under light irradiation. The different adhesion capabilities of solid and liquid states of PAzo-PEG endow it with reversible adhesive properties. The solid state exhibits better adhesion properties, with an adhesion strength of 0.97 MPa measured experimentally, while the adhesion strength of PAzo-PEG in the cis state is reduced to 0.03 MPa. After three cycles of adhesion, the adhesive strength maintained 80% of the original strength.
A reversible adhesive PAzo-PEG, with a main chain structure of methyl methacrylate and a side chain of azobenzene(Azo) having six methylene spacer groups and a short polyethylene glycol(PEG) chain as a tail group, can undergo solid to liquid transformation under UV and visible light irradiation. It was prepared by atom transfer radical polymerization (ATRP) the azobenzene group undergoes reversible trans-to-cis isomerization under UV and visible light irradiation, and the process is reversible. The reversible photoisomerization process of solid materials was studied by UV-Vis absorption spectroscopy. The solid-to-liquid transition was studied by differential scanning calorimetry (DSC). Results showed that the solid-liquid transition is due to the different glass transition temperatures (Tg) of the cis and trans isomers, and Tg of trans is higher than room temperature while Tg of cis is lower than room temperature, so PAzo-PEG macroscopically exhibits reversible solid-to-liquid transition under light irradiation. The different adhesion capabilities of solid and liquid states of PAzo-PEG endow it with reversible adhesive properties. The solid state exhibits better adhesion properties, with an adhesion strength of 0.97 MPa measured experimentally, while the adhesion strength of PAzo-PEG in the cis state is reduced to 0.03 MPa. After three cycles of adhesion, the adhesive strength maintained 80% of the original strength.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230114001
Abstract:
Hydrogels are a type of high-water content and crosslinked polymer networks, which can produce a volumetric expansion or contraction through a water absorption or loss process under external environmental stimulation. Due to their good biocompatibility and adjustable mechanical properties, hydrogels have attracted wide attentions and have been extensively applied in the fields of tissue engineering, biomimetic deformation and intelligent actuation. Light is a non-contact, fast switching and high spatiotemporal resolution stimulus, and therefore is used to regulate the macroscopic structure and properties of hydrogels through photothermal effects, photochemical reactions or photoisomerization. Among them, photoisomerization of molecular switches has a broader application potential because of its advantages of mild irradiation conditions and high reversibility. In this review, we summarized the state-of-the-art of photoresponsive hydrogels based on molecular photoisomerization, emphasizing the principle of molecular design as well as applications in biomimetic actuation, and eventually address their perspectives and challenges in the future development.
Hydrogels are a type of high-water content and crosslinked polymer networks, which can produce a volumetric expansion or contraction through a water absorption or loss process under external environmental stimulation. Due to their good biocompatibility and adjustable mechanical properties, hydrogels have attracted wide attentions and have been extensively applied in the fields of tissue engineering, biomimetic deformation and intelligent actuation. Light is a non-contact, fast switching and high spatiotemporal resolution stimulus, and therefore is used to regulate the macroscopic structure and properties of hydrogels through photothermal effects, photochemical reactions or photoisomerization. Among them, photoisomerization of molecular switches has a broader application potential because of its advantages of mild irradiation conditions and high reversibility. In this review, we summarized the state-of-the-art of photoresponsive hydrogels based on molecular photoisomerization, emphasizing the principle of molecular design as well as applications in biomimetic actuation, and eventually address their perspectives and challenges in the future development.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230223002
Abstract:
Recent developments have shown that purely organic molecules exploiting thermally activated delayed fluorescence (TADF) in organic light-emitting diodes (OLEDs) can utilize non-emissive triplet excitons for light emission through reverse intersystem crossing (RISC) processes. As a result, the exciton utilization efficiencies of TADF-based OLEDs can approach 100%. The electroluminescent molecule with TADF characteristics combines the advantages of the first-generation fluorescent emitters and the second-generation phosphorescent emitters by realizing 100% internal quantum efficiencies while reducing the material cost for commercialization. TADF materials now represent the third-generation of OLED emitters and offer an effective approach to breaking through the bottleneck of blue OLEDs. In this review, we focus on the development of high-performance blue TADF molecules, systematically elaborating on the design strategy of efficient and stable blue TADF molecules. Our discussion includes the achievement of high photoluminescence quantum yield, short excition lifetime, narrow full width half maximum, good molecular horizontal orientation and excellent stability. We aim to provide a scientific basis for the development of high-efficiency and stable blue TADF molecules. Additionally, we include an overview of outstanding issues and the research prospects of blue TADF molecules. We hope that this review contributes to the advancement of the field and provides insight into the design of high-performance blue TADF materials.
Recent developments have shown that purely organic molecules exploiting thermally activated delayed fluorescence (TADF) in organic light-emitting diodes (OLEDs) can utilize non-emissive triplet excitons for light emission through reverse intersystem crossing (RISC) processes. As a result, the exciton utilization efficiencies of TADF-based OLEDs can approach 100%. The electroluminescent molecule with TADF characteristics combines the advantages of the first-generation fluorescent emitters and the second-generation phosphorescent emitters by realizing 100% internal quantum efficiencies while reducing the material cost for commercialization. TADF materials now represent the third-generation of OLED emitters and offer an effective approach to breaking through the bottleneck of blue OLEDs. In this review, we focus on the development of high-performance blue TADF molecules, systematically elaborating on the design strategy of efficient and stable blue TADF molecules. Our discussion includes the achievement of high photoluminescence quantum yield, short excition lifetime, narrow full width half maximum, good molecular horizontal orientation and excellent stability. We aim to provide a scientific basis for the development of high-efficiency and stable blue TADF molecules. Additionally, we include an overview of outstanding issues and the research prospects of blue TADF molecules. We hope that this review contributes to the advancement of the field and provides insight into the design of high-performance blue TADF materials.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230202001
Abstract:
Flexible electronic devices have developed rapidly in recent years, but there are also some drawbacks such as weak interface adhesion and poor energy absorption and buffer ability. Aiming at the above defects, a series of impact hardening polymer elastomer with adhesion (IHP-EA) is designed by in situ crosslinking strategy using the combination of stable and dynamic crosslinking. Herein, the impact harden polymer (IHP) synthesized by silanol-terminated polydimethysiloxane (PDMS-OH) and trimethoxyboroxine (TMOB) constructed a dynamic crosslinking network to provide self-healing and energy absorption characteristics; the chemical crosslinked polydimethysiloxane (PDMS) network increased mechanical strength; while poly2-((((butylamino)carbonyl)oxo) methacrylate) (PBM) was prepared by free radical polymerization as an adhesion functional component to form high density hydrogen bonds with the substrate. The tensile strength and elongation at break of IHP-EA are 0.26 MPa and 177%, respectively, at strain rates of 50 mm/min. Normally, the toughness of PDMS materials rapidly decreased with the increasing of strain rate, while on the contrast, IHP-EA showed an obviously increasing toughness together with the increasing tensile rate, which indicated the significant strain rate responsiveness of IHP-EA. Therefore, IHP-EA has outstanding energy absorption and buffer effect, and the impact energy absorption efficiency could reach higher than 78% under an impact velocity of 4.43 m/s , much higher than that of conventional PDMS elastomer. In addition, IHP-EA has excellent interfacial adhesion performance, with the adhesion strength on glass substrate up to 198 kPa, almost 100 times higher than ordinary PDMS materials. In addition, IHP-EA also performed self-healing characteristic (healing efficiency exceeds 88%) and transparent performance (greater than 90%). These outstanding properties make the IHP-EA a potential candidate for application in flexible electronics and wearable protective materials.
Flexible electronic devices have developed rapidly in recent years, but there are also some drawbacks such as weak interface adhesion and poor energy absorption and buffer ability. Aiming at the above defects, a series of impact hardening polymer elastomer with adhesion (IHP-EA) is designed by in situ crosslinking strategy using the combination of stable and dynamic crosslinking. Herein, the impact harden polymer (IHP) synthesized by silanol-terminated polydimethysiloxane (PDMS-OH) and trimethoxyboroxine (TMOB) constructed a dynamic crosslinking network to provide self-healing and energy absorption characteristics; the chemical crosslinked polydimethysiloxane (PDMS) network increased mechanical strength; while poly2-((((butylamino)carbonyl)oxo) methacrylate) (PBM) was prepared by free radical polymerization as an adhesion functional component to form high density hydrogen bonds with the substrate. The tensile strength and elongation at break of IHP-EA are 0.26 MPa and 177%, respectively, at strain rates of 50 mm/min. Normally, the toughness of PDMS materials rapidly decreased with the increasing of strain rate, while on the contrast, IHP-EA showed an obviously increasing toughness together with the increasing tensile rate, which indicated the significant strain rate responsiveness of IHP-EA. Therefore, IHP-EA has outstanding energy absorption and buffer effect, and the impact energy absorption efficiency could reach higher than 78% under an impact velocity of 4.43 m/s , much higher than that of conventional PDMS elastomer. In addition, IHP-EA has excellent interfacial adhesion performance, with the adhesion strength on glass substrate up to 198 kPa, almost 100 times higher than ordinary PDMS materials. In addition, IHP-EA also performed self-healing characteristic (healing efficiency exceeds 88%) and transparent performance (greater than 90%). These outstanding properties make the IHP-EA a potential candidate for application in flexible electronics and wearable protective materials.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230307002
Abstract:
Bovine serum albumin (BSA) molecularly imprinted polymer (MIP) surface plasmon resonance (SPR) biosensors were prepared using BSA as a model, dopamine as the functional monomer and cross-linker and sodium periodate as the oxidant. BSA molecules were fixed in advance through hydrogen bond via introducing poly(acrylic acid) (PAA-SH) to increase recognition sites, and partially hydrolyzed poly(2-methyl-2-oxazoline)(PMOXA-EI) was also introduced into the noncavity regions of polydopamine to resist nonspecific adsorption of proteins. The prepared BSA-MIP SPR sensor was characterized by X-ray photoelectron spectroscopy, atomic force microscopy, variable angle spectroscopic ellipsometry, and static water contact angle. SPR adsorption studies were carried out in aqueous BSA solutions with the mass concentration of 0.1—10 μg/mL. The limit of detection and the limit of quantification values were obtained as 53 ng/mL and 161 ng/mL, respectively. Selectivity studies were performed against β-lactoglobulin, ovalbumin, lysozyme, and cytochrome C, and the corresponding selectivity coefficients were determined to be 4.43、3.45、3.17 and 3.64, respectively. Finally, BSA-MIP biosensor was used to detect BSA in the mixture solution of the above five proteins. The BSA recovery rate was 97.5% to 102.5%.
Bovine serum albumin (BSA) molecularly imprinted polymer (MIP) surface plasmon resonance (SPR) biosensors were prepared using BSA as a model, dopamine as the functional monomer and cross-linker and sodium periodate as the oxidant. BSA molecules were fixed in advance through hydrogen bond via introducing poly(acrylic acid) (PAA-SH) to increase recognition sites, and partially hydrolyzed poly(2-methyl-2-oxazoline)(PMOXA-EI) was also introduced into the noncavity regions of polydopamine to resist nonspecific adsorption of proteins. The prepared BSA-MIP SPR sensor was characterized by X-ray photoelectron spectroscopy, atomic force microscopy, variable angle spectroscopic ellipsometry, and static water contact angle. SPR adsorption studies were carried out in aqueous BSA solutions with the mass concentration of 0.1—10 μg/mL. The limit of detection and the limit of quantification values were obtained as 53 ng/mL and 161 ng/mL, respectively. Selectivity studies were performed against β-lactoglobulin, ovalbumin, lysozyme, and cytochrome C, and the corresponding selectivity coefficients were determined to be 4.43、3.45、3.17 and 3.64, respectively. Finally, BSA-MIP biosensor was used to detect BSA in the mixture solution of the above five proteins. The BSA recovery rate was 97.5% to 102.5%.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221130001
Abstract:
A riboregulator called toehold switch has been designed. In this riboregulator, the start codon AUG and ribosome binding site (RBS) are located on the loop of the hairpin structure, resulting in the stem structure with a completely complementary double-stranded RNA. Trigger RNA can open the hairpin through strand displacement reaction, and activate the downstream expression of green fluorescence protein (GFP), leading to a certain increasing of fluorescence signal, eventually realizing the regulation of E. coli gene expression. The effects of stem length on the expression of GFP were investigated. Results showed that the hairpin structure of toehold switch could effectively inhibit the expression of green fluorescent protein when the length of stem was more than 8 bp. Further co-expression experiments showed that trigger RNA could open the structure of hairpin RNA, resulting in a certain increasing of expression of GFP, and regulate the gene expression of E. coli. The E. coli gene expression system regulated by toehold switch is scalable and can be applied to the regulation of multi-gene expression, which has potential application value in the diagnosis and treatment of gene diseases.
A riboregulator called toehold switch has been designed. In this riboregulator, the start codon AUG and ribosome binding site (RBS) are located on the loop of the hairpin structure, resulting in the stem structure with a completely complementary double-stranded RNA. Trigger RNA can open the hairpin through strand displacement reaction, and activate the downstream expression of green fluorescence protein (GFP), leading to a certain increasing of fluorescence signal, eventually realizing the regulation of E. coli gene expression. The effects of stem length on the expression of GFP were investigated. Results showed that the hairpin structure of toehold switch could effectively inhibit the expression of green fluorescent protein when the length of stem was more than 8 bp. Further co-expression experiments showed that trigger RNA could open the structure of hairpin RNA, resulting in a certain increasing of expression of GFP, and regulate the gene expression of E. coli. The E. coli gene expression system regulated by toehold switch is scalable and can be applied to the regulation of multi-gene expression, which has potential application value in the diagnosis and treatment of gene diseases.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221231001
Abstract:
Cytoskeletal networks usually refer to cellular structures that are comprised of microtubules, actin filaments, intermediate filaments, and their associated accessory proteins and motor proteins, facilitating a range of cellular functions such as cell motion, division and growth. In addition to the narrow definition of “cytoskeleton” that provides frame support to an otherwise fluidic cell, cytoskeletal polymers play an important role in many other cellular functions. For example, bacteria flagella and spindle apparatus are essentially microtubules in different forms. In living cells, there are also hundreds of proteins and biochemical factors regulating the structure and dynamics of such networks, which makes it extremely difficult to elucidate the physical mechanisms behind these processes. In recent years, study of in vitro cytoskeletal polymer-motor protein networks built from purified protein components not only helps to understand the fundamental principles of non-equilibrium self-organization and dynamic behavior of cytoskeletal polymers and motor proteins on the subcellular level, but also sheds light on the design of active matter system and active machines that may operate far from equilibrium with life-like behaviors and functions. One notable success is the artificial active nematics built upon microtubules and kinesin motors, in which active stresses are used to generate macroscopic active flow and guide materials assembly. The active stress and order emergence of materials organization can also be tuned by a set of external parameters, such as external magnetic fields and light-activated proteins, in addition to the concentration of protein building blocks, ATP, and crowding agents. In this review, we focus on in vitro cytoskeleton-motor protein networks based on purified components including tubulin, actin, kinesin, and myosin, emphasizing on the non-equilibrium nature of microtubule and F-actin polymerization, generation of active stress and formation of dynamic networks, as well as the self-organization and dynamic behavior of subcellular structures on a larger scale. We conclude with the application of such networks in the study of active matter and artificial cells.
Cytoskeletal networks usually refer to cellular structures that are comprised of microtubules, actin filaments, intermediate filaments, and their associated accessory proteins and motor proteins, facilitating a range of cellular functions such as cell motion, division and growth. In addition to the narrow definition of “cytoskeleton” that provides frame support to an otherwise fluidic cell, cytoskeletal polymers play an important role in many other cellular functions. For example, bacteria flagella and spindle apparatus are essentially microtubules in different forms. In living cells, there are also hundreds of proteins and biochemical factors regulating the structure and dynamics of such networks, which makes it extremely difficult to elucidate the physical mechanisms behind these processes. In recent years, study of in vitro cytoskeletal polymer-motor protein networks built from purified protein components not only helps to understand the fundamental principles of non-equilibrium self-organization and dynamic behavior of cytoskeletal polymers and motor proteins on the subcellular level, but also sheds light on the design of active matter system and active machines that may operate far from equilibrium with life-like behaviors and functions. One notable success is the artificial active nematics built upon microtubules and kinesin motors, in which active stresses are used to generate macroscopic active flow and guide materials assembly. The active stress and order emergence of materials organization can also be tuned by a set of external parameters, such as external magnetic fields and light-activated proteins, in addition to the concentration of protein building blocks, ATP, and crowding agents. In this review, we focus on in vitro cytoskeleton-motor protein networks based on purified components including tubulin, actin, kinesin, and myosin, emphasizing on the non-equilibrium nature of microtubule and F-actin polymerization, generation of active stress and formation of dynamic networks, as well as the self-organization and dynamic behavior of subcellular structures on a larger scale. We conclude with the application of such networks in the study of active matter and artificial cells.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20221128001
Abstract:
Polycation exhibit great potential application in the fields of anti-infection, especially in combating drug-resistant bacteria and breaking through the barrier of biofilm. To enhance the interaction between the prepared polymers and bacteria and the bacterial killing efficacy, a series of biocompatible polycations with excellent performance have been designed and constructed. In this review, the recent progresses in design, preparation, and the application of functional cationic antimicrobial polymers are summarized, and the antimalarial mechanism and the unique properties are discussed. Finally, the current challenges and future perspectives in cationic antimicrobial polymers are put forward.
Polycation exhibit great potential application in the fields of anti-infection, especially in combating drug-resistant bacteria and breaking through the barrier of biofilm. To enhance the interaction between the prepared polymers and bacteria and the bacterial killing efficacy, a series of biocompatible polycations with excellent performance have been designed and constructed. In this review, the recent progresses in design, preparation, and the application of functional cationic antimicrobial polymers are summarized, and the antimalarial mechanism and the unique properties are discussed. Finally, the current challenges and future perspectives in cationic antimicrobial polymers are put forward.
, Available online ,
doi: 10.14133/j.cnki.1008-9357.20230207001
Abstract:
Bacterial infection seriously endangers patients' health. Thus, it is imperative to develop highly efficient antibacterial materials. In this study, antibacterial and antioxidant hydrogel with photothermal effect and nitric oxide (NO) gas-releasing property was designed and synthesized. The hydrogel was formed by crosslinking ε-polylysine and tannic acid using Fe3+ and glutaraldehyde and loading NO donor S-nitroso-N-acetyl-DL penicillamine (SNAP). The NO-Fe9-TA20 hydrogel shows high photothermal effect and the temperature of hydrogel can reach 43.8 ℃ within 10 minutes under 1 W/cm2 near-infrared irradiation. Additionally, the NO-Fe9-TA20 hydrogel shows effective NO-release activities. Under visible light and at 37 ℃, the amount of NO released from the hydrogel reached 36.48 μM within 3 h. Benefitting from the synergetic effect of cations of ε-poly-L-lysine (EPL) and the released NO, NO-Fe9-TA20 hydrogel exhibits antibacterial activity (> 99.9%) towards Staphylococcus aureus, and can effectively scavenge 1,1-dipheny-2-picrylhydrazyl (DPPH) free radicals (> 84.3%), which may protect cells from oxidative stress damage. This study may provide a new approach for bacterial infections treatment.
Bacterial infection seriously endangers patients' health. Thus, it is imperative to develop highly efficient antibacterial materials. In this study, antibacterial and antioxidant hydrogel with photothermal effect and nitric oxide (NO) gas-releasing property was designed and synthesized. The hydrogel was formed by crosslinking ε-polylysine and tannic acid using Fe3+ and glutaraldehyde and loading NO donor S-nitroso-N-acetyl-DL penicillamine (SNAP). The NO-Fe9-TA20 hydrogel shows high photothermal effect and the temperature of hydrogel can reach 43.8 ℃ within 10 minutes under 1 W/cm2 near-infrared irradiation. Additionally, the NO-Fe9-TA20 hydrogel shows effective NO-release activities. Under visible light and at 37 ℃, the amount of NO released from the hydrogel reached 36.48 μM within 3 h. Benefitting from the synergetic effect of cations of ε-poly-L-lysine (EPL) and the released NO, NO-Fe9-TA20 hydrogel exhibits antibacterial activity (> 99.9%) towards Staphylococcus aureus, and can effectively scavenge 1,1-dipheny-2-picrylhydrazyl (DPPH) free radicals (> 84.3%), which may protect cells from oxidative stress damage. This study may provide a new approach for bacterial infections treatment.
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Display Method:
2023, 36(2): 95-106.
doi: 10.14133/j.cnki.1008-9357.20221017001
Abstract:
Ionic porous organic polymer (i-POP) is an emerging class of organic porous polyelectrolytes featuring ionized backbones or side groups on the skeletons. i-POPs are highly designable exhibiting large specific surface areas and intrinsic nanopores. Their physicochemical properties and functionality can be skillfully regulated by varying ionized building blocks. Compared with neutral porous organic polymers, i-POPs possess controllable ionic sites and high charge density, broadening the application ranges of porous organic polymers. Meanwhile, their applicability can be strengthened by the inherent association between pore confinement, skeleton function, and abundant ionic sites. The compositions, structures, and synthetic methods of amorphous i-POPs have been significantly explored in recent years. Tremendous studies have demonstrated that i-POPs are promising for various advanced applications including adsorption/separation, sensing, catalysis and so on.
Ionic porous organic polymer (i-POP) is an emerging class of organic porous polyelectrolytes featuring ionized backbones or side groups on the skeletons. i-POPs are highly designable exhibiting large specific surface areas and intrinsic nanopores. Their physicochemical properties and functionality can be skillfully regulated by varying ionized building blocks. Compared with neutral porous organic polymers, i-POPs possess controllable ionic sites and high charge density, broadening the application ranges of porous organic polymers. Meanwhile, their applicability can be strengthened by the inherent association between pore confinement, skeleton function, and abundant ionic sites. The compositions, structures, and synthetic methods of amorphous i-POPs have been significantly explored in recent years. Tremendous studies have demonstrated that i-POPs are promising for various advanced applications including adsorption/separation, sensing, catalysis and so on.
2023, 36(2): 107-116.
doi: 10.14133/j.cnki.1008-9357.20221107001
Abstract:
At present, the existing scaffold materials cannot well meet the high strength and toughness requirements for the repairing of typical stressed tissues. And the commercial software for 3D printing scaffold modeling and mechanical performance simulation is complex to operate and has poor interoperability with 3D printers. In order to solve these problems, a silk fibroin (SF) based bio-ink was prepared for tough scaffold, and a software was developed for compression performance simulation of 3D printing scaffold based on SF and finite element analysis strategy. The printability of the bio-ink and the mechanical properties of the corresponding hydrogels and 3D printing scaffolds were characterized. The cell compatibility of the related scaffolds was evaluated by using fibroblasts and living/dead staining kit. Based on the SF based bio-ink, scaffolds with different heights and porosities were designed and printed. By using the developed software and the universal testing machine, the compression performance of related scaffolds was simulated and tested separately, and further compared with each other. Results show that the SF based bio-ink has good printability. And the 3D printing scaffold prepared by this ink presents high strength and toughness (modulus of elasticity: (1.86 ± 0.28)MPa, modulus of compression: (1.95 ± 0.11)MPa, elongation at break: (114.03 ± 14.40)%, compression strain ≥ 70%). In addition, the scaffold has good cell compatibility (L929 cell viability≥92.4%), which is expected to be used for the repair and regeneration of stressed tissues. The software is easy to operate, and can be used not only for the modeling of 3D printing scaffolds, but also for accurately predicting their compressive mechanical properties. In addition, the model data can also be directly imported into the 3D printer to guide the efficient preparation of the corresponding 3D printing scaffolds. This research is expected to provide important guidance for the rapid design and fabrication of tissue specific 3D printing scaffolds with bionic structure and mechanical properties.
At present, the existing scaffold materials cannot well meet the high strength and toughness requirements for the repairing of typical stressed tissues. And the commercial software for 3D printing scaffold modeling and mechanical performance simulation is complex to operate and has poor interoperability with 3D printers. In order to solve these problems, a silk fibroin (SF) based bio-ink was prepared for tough scaffold, and a software was developed for compression performance simulation of 3D printing scaffold based on SF and finite element analysis strategy. The printability of the bio-ink and the mechanical properties of the corresponding hydrogels and 3D printing scaffolds were characterized. The cell compatibility of the related scaffolds was evaluated by using fibroblasts and living/dead staining kit. Based on the SF based bio-ink, scaffolds with different heights and porosities were designed and printed. By using the developed software and the universal testing machine, the compression performance of related scaffolds was simulated and tested separately, and further compared with each other. Results show that the SF based bio-ink has good printability. And the 3D printing scaffold prepared by this ink presents high strength and toughness (modulus of elasticity: (1.86 ± 0.28)MPa, modulus of compression: (1.95 ± 0.11)MPa, elongation at break: (114.03 ± 14.40)%, compression strain ≥ 70%). In addition, the scaffold has good cell compatibility (L929 cell viability≥92.4%), which is expected to be used for the repair and regeneration of stressed tissues. The software is easy to operate, and can be used not only for the modeling of 3D printing scaffolds, but also for accurately predicting their compressive mechanical properties. In addition, the model data can also be directly imported into the 3D printer to guide the efficient preparation of the corresponding 3D printing scaffolds. This research is expected to provide important guidance for the rapid design and fabrication of tissue specific 3D printing scaffolds with bionic structure and mechanical properties.
2023, 36(2): 117-125.
doi: 10.14133/j.cnki.1008-9357.20221203001
Abstract:
Monodisperse SiO2 microspheres with particle size in the range of 208—368 nm were prepared by the Stöber method and used to construct structural color films via fast lifting method. The as-prepared structural color films were then embedded in polydimethylsiloxane (PDMS), on which polydopamine (PDA)-doped PDMS (PDMS-PDA) was coated to obtain stretchable color-changing PDMS/SiO2/PDMS-PDA photonic elastomer films. Both the structural color films and photonic elastomer films were explored with techniques including scanning electron microscope, nanoscale laser particle size analyzer, spectrophotometer, fiber optic spectrometer, tensile testing machine and digital camera to elucidate the microstructure and optical properties of the former and the strain response and mechanical properties of the latter. Results show that the structural color films belong to amorphous photonic crystals consisting of long-range disordered and short-range ordered arrangements of SiO2 microspheres, and their structural colors are angle-independent under diffuse light. But interestingly, the structural colors are angle-dependent under sunlight due to the surface of SiO2 microspheres arranged flatly. As for the photonic crystal elastomer films surface-coated with a black PDMS-PDA layer, the saturation of the structural color of the films during stretching is greatly improved. When the tensile strain reaches 20%, the films start to show apparently structural color, which undergo a continuous blue-shift with increasing strain, and the color returns to the initial state when the strain is restored. Moreover, the film has good mechanical properties with an elongation at the break of 140%, and can be applied to the field of visualized flexible sensing, smart wearable devices and other fields.
Monodisperse SiO2 microspheres with particle size in the range of 208—368 nm were prepared by the Stöber method and used to construct structural color films via fast lifting method. The as-prepared structural color films were then embedded in polydimethylsiloxane (PDMS), on which polydopamine (PDA)-doped PDMS (PDMS-PDA) was coated to obtain stretchable color-changing PDMS/SiO2/PDMS-PDA photonic elastomer films. Both the structural color films and photonic elastomer films were explored with techniques including scanning electron microscope, nanoscale laser particle size analyzer, spectrophotometer, fiber optic spectrometer, tensile testing machine and digital camera to elucidate the microstructure and optical properties of the former and the strain response and mechanical properties of the latter. Results show that the structural color films belong to amorphous photonic crystals consisting of long-range disordered and short-range ordered arrangements of SiO2 microspheres, and their structural colors are angle-independent under diffuse light. But interestingly, the structural colors are angle-dependent under sunlight due to the surface of SiO2 microspheres arranged flatly. As for the photonic crystal elastomer films surface-coated with a black PDMS-PDA layer, the saturation of the structural color of the films during stretching is greatly improved. When the tensile strain reaches 20%, the films start to show apparently structural color, which undergo a continuous blue-shift with increasing strain, and the color returns to the initial state when the strain is restored. Moreover, the film has good mechanical properties with an elongation at the break of 140%, and can be applied to the field of visualized flexible sensing, smart wearable devices and other fields.
2023, 36(2): 126-135.
doi: 10.14133/j.cnki.1008-9357.20221225001
Abstract:
Wet (underwater) adhesive materials have wide applications in biomedical and engineering fields. However, a hydration layer on the substrate surface severely prevents the interface interaction between adhesives and substrates, resulting in sharp reduce or even disappearance of the wet adhesion property. Therefore, it is of great significance to prepare adhesive materials with wet adhesion property by removal of the hydration layer via hydrophobic interaction. In this paper, amino acid based monomers, N-acrylylglycine (ACG) and N-acrylyl-L-phenylalanine (ACP) were synthesized, and then poly(N-acrylylglycine-N-acrylyl-L-phenylalanine) hydrogels (P(ACGx-ACPy)) were further prepared via hydrogen cross-linking and chemical cross-linking. The intermolecular interactions and properties of the P(ACGx-ACPy) hydrogels were regulated by adjusting the composition ratio of ACG to ACP. Their adhesive properties were then detected by lap-shear and tensile tests, respectively. The results showed that the hydrogels had well adhesive properties. The maximum wet lap-shear adhesive strength to pig skin could reach 80.2 kPa, when the molar ratio of ACG to ACP of hydrogel was 1∶1. Moreover, the highest compression strength of the hydrogels was 2.2 MPa. Cytotoxicity tests showed that hydrogels had good biocompatibility. The prepared P(ACGx-ACPy) adhesives has the potential applications to bio-tissue and other wet materials repairing.
Wet (underwater) adhesive materials have wide applications in biomedical and engineering fields. However, a hydration layer on the substrate surface severely prevents the interface interaction between adhesives and substrates, resulting in sharp reduce or even disappearance of the wet adhesion property. Therefore, it is of great significance to prepare adhesive materials with wet adhesion property by removal of the hydration layer via hydrophobic interaction. In this paper, amino acid based monomers, N-acrylylglycine (ACG) and N-acrylyl-L-phenylalanine (ACP) were synthesized, and then poly(N-acrylylglycine-N-acrylyl-L-phenylalanine) hydrogels (P(ACGx-ACPy)) were further prepared via hydrogen cross-linking and chemical cross-linking. The intermolecular interactions and properties of the P(ACGx-ACPy) hydrogels were regulated by adjusting the composition ratio of ACG to ACP. Their adhesive properties were then detected by lap-shear and tensile tests, respectively. The results showed that the hydrogels had well adhesive properties. The maximum wet lap-shear adhesive strength to pig skin could reach 80.2 kPa, when the molar ratio of ACG to ACP of hydrogel was 1∶1. Moreover, the highest compression strength of the hydrogels was 2.2 MPa. Cytotoxicity tests showed that hydrogels had good biocompatibility. The prepared P(ACGx-ACPy) adhesives has the potential applications to bio-tissue and other wet materials repairing.
2023, 36(2): 136-145.
doi: 10.14133/j.cnki.1008-9357.20220922001
Abstract:
In order to develop a wound dressing loaded with pomegranate peel extract (PPE), the hydrogel was prepared by cyclic freeze-thaw method using polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (Na-CMC) as raw materials, glycerol (GL) aqueous solution was used as the solvent. Subsequently, the chemical structure of hydrogels was analyzed by FT-IR. In addition, the transmittance, anti-drying, swelling, tensile properties, in vitro drug release, anti-oxidation and antibacterial properties of hydrogels were also studied. Results showed that the prepared hydrogels had good drying resistance and could remain intact at room temperature for 72 h. The addition of PPE reduced the light transmittance of the hydrogel, improved the swelling and tensile property of the hydrogel, and made the hydrogel have good antibacterial and antioxidant properties. The cumulative release of PPE in the hydrogel was (67.47 ± 3.75)%, which showed good antibacterial activity against Staphylococcus aureus and Escherichia coli. The inhibition zones were (18.78 ± 0.26) mm and (15.11 ± 0.23) mm, respectively. The highest scavenging rate to 1,1-diphenyl-2-picrylhydrazyl (DPPH) was (93.65 ± 2.27)%. Therefore, the hydrogel loaded with PPE prepared in this study has the potential as a wound dressing.
In order to develop a wound dressing loaded with pomegranate peel extract (PPE), the hydrogel was prepared by cyclic freeze-thaw method using polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (Na-CMC) as raw materials, glycerol (GL) aqueous solution was used as the solvent. Subsequently, the chemical structure of hydrogels was analyzed by FT-IR. In addition, the transmittance, anti-drying, swelling, tensile properties, in vitro drug release, anti-oxidation and antibacterial properties of hydrogels were also studied. Results showed that the prepared hydrogels had good drying resistance and could remain intact at room temperature for 72 h. The addition of PPE reduced the light transmittance of the hydrogel, improved the swelling and tensile property of the hydrogel, and made the hydrogel have good antibacterial and antioxidant properties. The cumulative release of PPE in the hydrogel was (67.47 ± 3.75)%, which showed good antibacterial activity against Staphylococcus aureus and Escherichia coli. The inhibition zones were (18.78 ± 0.26) mm and (15.11 ± 0.23) mm, respectively. The highest scavenging rate to 1,1-diphenyl-2-picrylhydrazyl (DPPH) was (93.65 ± 2.27)%. Therefore, the hydrogel loaded with PPE prepared in this study has the potential as a wound dressing.
2023, 36(2): 146-152.
doi: 10.14133/j.cnki.1008-9357.20220922003
Abstract:
Organic second-order nonlinear optical (NLO) materials have broad application prospects in a new generation of high-performance, high-bandwidth electro-optic modulation devices due to their high responsiveness, high integration, low cost, and good designability. However, the organic second-order NLO materials present relatively lower alignment stability compared with inorganic materials, which limits its wide application. In this paper, cross-linkable anthracene groups are introduced into the side chains of polymer for enhancing alignment stability by [4+4] cycloaddition reaction of anthracene groups under UV light irradiation. Methylmethacrylate based copolymers p1 —p3 containing different concentration of anthracene groups were synthesized by solution polymerization. Then chromophores were doped in p1—p3 to prepare second-order nonlinear optical films. The time required for the complete reaction of anthracene groups in the polymer film was studied by UV-Vis spectroscopy. After 30 min irradiation, the crosslinking reaction could complete and the chromophores during irradiation didn’t exhibit decomposition. The results of differential scanning calorimetry (DSC) showed that the glass transition temperature（Tg） of the polymer film increased by 10 ℃ after the cross-linking reaction. As the TGA analysis, 5% mass fraction decomposition temperature increased with anthracene group from 210 ℃ to 240 ℃. The electro-optic properties and orientation stability of the cross-linked materials were investigated. After heating at 60 ℃ for 220 h, electro-optic properties retained around 90% after photo-crosslinking. Peak temperature of the thermal stimulated current (TSD) of the crosslinked film increased around 15 ℃ compared with uncrosslinked one. The results show that the orientation stability of the second-order nonlinear polymer has been improved to a certain extent.
Organic second-order nonlinear optical (NLO) materials have broad application prospects in a new generation of high-performance, high-bandwidth electro-optic modulation devices due to their high responsiveness, high integration, low cost, and good designability. However, the organic second-order NLO materials present relatively lower alignment stability compared with inorganic materials, which limits its wide application. In this paper, cross-linkable anthracene groups are introduced into the side chains of polymer for enhancing alignment stability by [4+4] cycloaddition reaction of anthracene groups under UV light irradiation. Methylmethacrylate based copolymers p1 —p3 containing different concentration of anthracene groups were synthesized by solution polymerization. Then chromophores were doped in p1—p3 to prepare second-order nonlinear optical films. The time required for the complete reaction of anthracene groups in the polymer film was studied by UV-Vis spectroscopy. After 30 min irradiation, the crosslinking reaction could complete and the chromophores during irradiation didn’t exhibit decomposition. The results of differential scanning calorimetry (DSC) showed that the glass transition temperature（Tg） of the polymer film increased by 10 ℃ after the cross-linking reaction. As the TGA analysis, 5% mass fraction decomposition temperature increased with anthracene group from 210 ℃ to 240 ℃. The electro-optic properties and orientation stability of the cross-linked materials were investigated. After heating at 60 ℃ for 220 h, electro-optic properties retained around 90% after photo-crosslinking. Peak temperature of the thermal stimulated current (TSD) of the crosslinked film increased around 15 ℃ compared with uncrosslinked one. The results show that the orientation stability of the second-order nonlinear polymer has been improved to a certain extent.
2023, 36(2): 153-159.
doi: 10.14133/j.cnki.1008-9357.20220926001
Abstract:
4-(ω-(methylimidazole) hexyloxy)-4 ′-(cyano)-biphenyl (CbP) was synthesized using 1,6-dibromohexane, cyanobiphenol and N-methyl imidazole as main materials. The wood pulp cellulose solution was prepared by adding CbP to ionic liquid 1-allyl-3-methylimidazolium chloride（AMIM•Cl） as a cellulose solvent, and then its rheological property was tested by Haake rheometer. Wood pulp cellulose liquid crystal films (WPC/CbP) were prepared from the solution by dipping precipitation phase transformation. Fourier infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure of the film and differential scanning calorimetry (DSC) was used to characterize the thermal stability of the film. The strength of the film was tested by electronic universal tensile testing machine, and the UV resistance of the film was tested by UV-visible near-infrared spectrometer. Results showed that the viscosity of WPC/CbP increased with the increase of the mass fraction of CbP, and the lowest value appeared when the mass fraction of CbP was 3%, in which a liquid crystal phenomenon was observed by polarizing microscope (POM). Compared with WPC film, the thermal stability and tensile strength of the WPC/CbP were improved because of the intramolecular and intermolecular hydrogen bonds of cellulose and CbP. The tensile strength and flexibility of the WPC/CbP were improved by 27.56% and 46.52%, respectively. However, the UV transmittance of the WPC/CbP was reduced by about 35%, indicating its potential application in the field of high strength packaging.
4-(ω-(methylimidazole) hexyloxy)-4 ′-(cyano)-biphenyl (CbP) was synthesized using 1,6-dibromohexane, cyanobiphenol and N-methyl imidazole as main materials. The wood pulp cellulose solution was prepared by adding CbP to ionic liquid 1-allyl-3-methylimidazolium chloride（AMIM•Cl） as a cellulose solvent, and then its rheological property was tested by Haake rheometer. Wood pulp cellulose liquid crystal films (WPC/CbP) were prepared from the solution by dipping precipitation phase transformation. Fourier infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure of the film and differential scanning calorimetry (DSC) was used to characterize the thermal stability of the film. The strength of the film was tested by electronic universal tensile testing machine, and the UV resistance of the film was tested by UV-visible near-infrared spectrometer. Results showed that the viscosity of WPC/CbP increased with the increase of the mass fraction of CbP, and the lowest value appeared when the mass fraction of CbP was 3%, in which a liquid crystal phenomenon was observed by polarizing microscope (POM). Compared with WPC film, the thermal stability and tensile strength of the WPC/CbP were improved because of the intramolecular and intermolecular hydrogen bonds of cellulose and CbP. The tensile strength and flexibility of the WPC/CbP were improved by 27.56% and 46.52%, respectively. However, the UV transmittance of the WPC/CbP was reduced by about 35%, indicating its potential application in the field of high strength packaging.
2023, 36(2): 160-169.
doi: 10.14133/j.cnki.1008-9357.20220520001
Abstract:
Electrospun polycaprolactone (PCL) nanofibers are often used as biomedical materials for drug release systems and tissue engineering scaffolds due to their biodegradability, but the hydrophobicity and mechanical defects limit the wider applications. Here, polybutyrolactam (PBL), a biodegradable polyamide with excellent mechanical properties and high moisture regain, was blended with PCL in co-solvent to electrospin fiber membranes with improved mechanical properties and the hydrophilicity. Scanning electron microscope (SEM), water contact angle measuring instrument, atomic force microscope (AFM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), electronic universal tension machine were used to investigate the morphology, diameter and distribution of fibers, the hydrophilicity, crystallinity, thermal and mechanical properties of the fiber membranes. It was found that increasing the PBL content increased the fiber diameter, narrowed the diameter distribution, and significantly improved the hydrophilicity of the fiber membrane. PBL had been shown to be compatible with PCL, and the crystallinity of PCL/PBL electrospun fiber membranes with increasing PBL content was higher than that of monocomponent fiber membranes. Increasing the PBL content also slightly raised the melting point of the PCL component in the fiber membranes, while that of PBL remained unchanged. The crystallization temperatures of PBL and PCL, as well as the thermal stability of the fiber membranes decreased with increasing PBL content. The addition of PBL significantly improved the mechanical properties of electrospun fiber membranes. The greater PBL content was, the better the mechanical properties of the fiber membrane were.
Electrospun polycaprolactone (PCL) nanofibers are often used as biomedical materials for drug release systems and tissue engineering scaffolds due to their biodegradability, but the hydrophobicity and mechanical defects limit the wider applications. Here, polybutyrolactam (PBL), a biodegradable polyamide with excellent mechanical properties and high moisture regain, was blended with PCL in co-solvent to electrospin fiber membranes with improved mechanical properties and the hydrophilicity. Scanning electron microscope (SEM), water contact angle measuring instrument, atomic force microscope (AFM), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), electronic universal tension machine were used to investigate the morphology, diameter and distribution of fibers, the hydrophilicity, crystallinity, thermal and mechanical properties of the fiber membranes. It was found that increasing the PBL content increased the fiber diameter, narrowed the diameter distribution, and significantly improved the hydrophilicity of the fiber membrane. PBL had been shown to be compatible with PCL, and the crystallinity of PCL/PBL electrospun fiber membranes with increasing PBL content was higher than that of monocomponent fiber membranes. Increasing the PBL content also slightly raised the melting point of the PCL component in the fiber membranes, while that of PBL remained unchanged. The crystallization temperatures of PBL and PCL, as well as the thermal stability of the fiber membranes decreased with increasing PBL content. The addition of PBL significantly improved the mechanical properties of electrospun fiber membranes. The greater PBL content was, the better the mechanical properties of the fiber membrane were.
Preparation of High Toughness Polymer Composites with Self-Healing Capacity via Non-Covalent Bonding
2023, 36(2): 170-177.
doi: 10.14133/j.cnki.1008-9357.20221025001
Abstract:
Interfaces between nacreous tablets are crucial to the outstanding mechanical properties of nacre in natural shells and inspired by the “brick-and-mortar” structure and remarkable mechanical performance of nacre. Excellent research has been conducted to probe the effect of interfaces on strength and toughness of nacre, providing critical guidelines for the design of human-made laminated composites. Herein, a class of graphene oxide (GO) based artificial nacre composite material with self-healing capacity due to non-covalent bonding interactions was fabricated by functionalization of GO with ellagic acid through π-π stacking followed by evaporation-induced self assembling process between ellagic acid modified graphene oxide(EGO) and polyurethane(PU). The artificial nacre displays a strict “brick-and-mortar” structure, with EGO nanosheets as the brick and PU as the mortar. The structure of EGO was characterized by infrared spectroscopy, potential analyzer and X-ray diffraction, and the mechanical properties of PU-EGO were tested by universal testing machine. The results show that ellagic acid (ELA) is successfully adsorbed on GO surface, and when the mass ratio of PU to EGO is 3∶1, the tensile strength and toughness of the material reach 111.2 MPa and 81.5 MJ/m3, respectively (9.6 times and 1.8 times higher than that of PU), attributing to the interlayer slip of GO by breaking and recombing the π-π bond dynamically through which the energy can dissipate when PU-EGO is subjected to tensile stress. In addition, owning to the existence of non-covalent bonds, the resulting polymer composites display good recyclability. This work provides a pathway for the development of artificial nacre with self-healing capacity and recyclability.
Interfaces between nacreous tablets are crucial to the outstanding mechanical properties of nacre in natural shells and inspired by the “brick-and-mortar” structure and remarkable mechanical performance of nacre. Excellent research has been conducted to probe the effect of interfaces on strength and toughness of nacre, providing critical guidelines for the design of human-made laminated composites. Herein, a class of graphene oxide (GO) based artificial nacre composite material with self-healing capacity due to non-covalent bonding interactions was fabricated by functionalization of GO with ellagic acid through π-π stacking followed by evaporation-induced self assembling process between ellagic acid modified graphene oxide(EGO) and polyurethane(PU). The artificial nacre displays a strict “brick-and-mortar” structure, with EGO nanosheets as the brick and PU as the mortar. The structure of EGO was characterized by infrared spectroscopy, potential analyzer and X-ray diffraction, and the mechanical properties of PU-EGO were tested by universal testing machine. The results show that ellagic acid (ELA) is successfully adsorbed on GO surface, and when the mass ratio of PU to EGO is 3∶1, the tensile strength and toughness of the material reach 111.2 MPa and 81.5 MJ/m3, respectively (9.6 times and 1.8 times higher than that of PU), attributing to the interlayer slip of GO by breaking and recombing the π-π bond dynamically through which the energy can dissipate when PU-EGO is subjected to tensile stress. In addition, owning to the existence of non-covalent bonds, the resulting polymer composites display good recyclability. This work provides a pathway for the development of artificial nacre with self-healing capacity and recyclability.
2023, 36(2): 178-184.
doi: 10.14133/j.cnki.1008-9357.20221103001
Abstract:
Double network (DN) hydrogel was prepared by photoinitiated polymerization with gelatin (Gel) and hydroxyethyl methacrylate (HEMA) as monomers, methacryloylated gelatin (GelMA) as a cross-linking agent, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (I2959) as an initiator. Then the DN hydrogel was soaked into saturated Na2SO4 solution to prepare DN/SO42− hydrogel. Tensile property was tested by universal material testing machine. Results showed that when the mass fraction of Gel, HEMA, GelMA was 20%, 40%, and 10%, respectively, and the immersion time was 16 h, the tensile strength of the hydrogel could reach 0.94 MPa, and the elongation at break was 496%. Loading-unloading test showed that the hydrogel had good self-recovery performance. The hydrogel also had biodegradability because of the degradable cross-linking agent GelMA. It could be completely degraded after soaking in trypsin solution for 4 h. The molecular chains in the hydrogel network contracted in the high mass fraction salt solution and stretched in the low mass fraction salt solution, giving the shape memory of the hydrogel by ion stimulation response. The hydrogel with fixed shape (knotting, folding, twisting) could be recovered to its original shape within 5 min after soaking in low mass fraction Na2SO4 solution (w=2%). In addition, nontoxic components endowed the hydrogel with excellent biocompatibility, which had been confirmed by MTT method. After co-culture with different mass concentrations of DN/SO42− hydrogel extract solution, the viabilities of L929 cells were more than 80%.
Double network (DN) hydrogel was prepared by photoinitiated polymerization with gelatin (Gel) and hydroxyethyl methacrylate (HEMA) as monomers, methacryloylated gelatin (GelMA) as a cross-linking agent, and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (I2959) as an initiator. Then the DN hydrogel was soaked into saturated Na2SO4 solution to prepare DN/SO42− hydrogel. Tensile property was tested by universal material testing machine. Results showed that when the mass fraction of Gel, HEMA, GelMA was 20%, 40%, and 10%, respectively, and the immersion time was 16 h, the tensile strength of the hydrogel could reach 0.94 MPa, and the elongation at break was 496%. Loading-unloading test showed that the hydrogel had good self-recovery performance. The hydrogel also had biodegradability because of the degradable cross-linking agent GelMA. It could be completely degraded after soaking in trypsin solution for 4 h. The molecular chains in the hydrogel network contracted in the high mass fraction salt solution and stretched in the low mass fraction salt solution, giving the shape memory of the hydrogel by ion stimulation response. The hydrogel with fixed shape (knotting, folding, twisting) could be recovered to its original shape within 5 min after soaking in low mass fraction Na2SO4 solution (w=2%). In addition, nontoxic components endowed the hydrogel with excellent biocompatibility, which had been confirmed by MTT method. After co-culture with different mass concentrations of DN/SO42− hydrogel extract solution, the viabilities of L929 cells were more than 80%.
Accepted
Chinese Library Classification 