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    张龙, 张国颖. 蝌蚪形双亲水性嵌段共聚物的合成及其水溶液性质[J]. 功能高分子学报, 2020, 33(5): 452-459. doi: 10.14133/j.cnki.1008-9357.20191008001
    引用本文: 张龙, 张国颖. 蝌蚪形双亲水性嵌段共聚物的合成及其水溶液性质[J]. 功能高分子学报, 2020, 33(5): 452-459. doi: 10.14133/j.cnki.1008-9357.20191008001
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    ZHANG Long, ZHANG Guoying. Preparation and Solution Properties of Tadpole-Shaped Double Hydrophilic Diblock Copolymers[J]. Journal of Functional Polymers, 2020, 33(5): 452-459. doi: 10.14133/j.cnki.1008-9357.20191008001
    Citation: ZHANG Long, ZHANG Guoying. Preparation and Solution Properties of Tadpole-Shaped Double Hydrophilic Diblock Copolymers[J]. Journal of Functional Polymers, 2020, 33(5): 452-459. doi: 10.14133/j.cnki.1008-9357.20191008001
    shu

    蝌蚪形双亲水性嵌段共聚物的合成及其水溶液性质

    Preparation and Solution Properties of Tadpole-Shaped Double Hydrophilic Diblock Copolymers

      摘要
    • 摘要: 采用原子转移自由基聚合（ATRP）与分子内叠氮-炔基点击化学反应，合成具有环形聚（N-异丙基丙烯酰胺）（PNIPAM）“头部”和线形聚乙二醇（PEG）“尾巴”的温敏性蝌蚪形双亲水性两嵌段共聚物（PEG-b-cPNIPAM），并对其结构和水溶液性质进行了表征。GPC表征结果表明，蝌蚪形两嵌段共聚物比相同嵌段长度的线形两嵌段共聚物具有相对较小的分子量。当水溶液温度高于其相转变温度时，因PNIPAM嵌段的塌缩，线形和蝌蚪形两嵌段共聚物均可在水溶液中发生聚集。LLS测试结果表明，由于不存在链间缠结和贯穿，由蝌蚪形共聚物形成的聚集体具有相对更为疏松的结构和更小的流体力学半径。

       

      Abstract: Well-defined thermo-responsive tadpole-shaped double hydrophilic diblock copolymer (PEG45-b-cPNIPAM) was synthesized through the combination of atom transfer radical polymerization (ATRP) and intramolecular azide-alkynyl click chemistry reaction, where PEG was poly(ethylene glycol) and PNIPAM was poly(N-isopropylacrylamide). Firstly, PEG45(-alkynyl)-Br bearing an alkynyl end group and a bromo side group was synthesized as a macro-initiator to initiate the polymerization of N-isopropylacrylamide (NIPAM). Then, after the preparation of the thermo-responsive linear double hydrophilic diblock polymer, PEG45(-alkynyl)-b-lPNIPAM-Cl, which had an alkynyl and a chloro group at the terminal of PEG and PNIPAM block respectively, the chloro group was modified into azide group by the substitution reaction with sodium azide. Finally, via intramolecular azide-alkynyl click chemistry, PEG45-b-cPNIPAM was obtained, containing a cyclic PNIPAM “head” and a linear PEG “tail”. The structures of PEG45-b-cPNIPAM with different PNIPAM block lengths were characterized by Nuclear Magnetic Resonance (1H-NMR), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FT-IR) and Laser Light Scattering (LLS) measurements. GPC results indicated that due to the smaller mean square radius of gyration, PEG45-b-cPNIPAM possessed lower molecular weight than its corresponding control linear diblock copolymer with the same length of PEG and PNIPAM block. Moreover, LLS results showed that the solution properties of the polymers were greatly affected by their topological structure. Upon being heated above the phase transition temperature, both the linear and tadpole-shaped diblock copolymer formed aggregates in aqueous solution due to the collapse of the PNIPAM blocks. However, the hydrodynamic radius of the aggregates obtained from PEG-b-cPNIPAM was much smaller than that obtained from linear diblock copolymers with the same block length for lack of inter-chain entanglement. Besides, concerning the tadpole-shaped PEG45-b-cPNIPAM110 with longer PNIAPM block length, after the rapid phase transition, the collapsed polymer chains in the aggregates could further undergo conformation adjustment, thus resulting in the decrease of aggregates size with the increasing solution temperature.

       

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