Design and Performance of Dual Dynamic Crosslinked Polymer with Light and Thermal Tunable Properties

By incorporating dynamic imine bonds and anthracene moieties into a polymer matrix, we constructed a dual-dynamic cross-linked network and systematically investigated its photo-responsive behavior, rheological dynamics, and mechanical properties. Fourier-transform infrared spectroscopy (FT-IR) and ¹H nuclear magnetic resonance (¹H-NMR) confirmed that the target polymer bearing both dynamic imine linkages and photo-responsive groups was successfully synthesized. UV–vis spectroscopy revealed four characteristic absorption peaks in the range of 300 nm to 400 nm, allowing the evolution of the chemical structure under irradiation to be directly monitored and verifying the occurrence of the photocrosslinking reaction. To elucidate the effect of irradiation time on mechanical performance, tensile tests were conducted after precisely controlled exposure periods. As irradiation time increased, the Young’s modulus rose steadily from 10.33 MPa to 17.52 MPa, while the elongation at break decreased from 167 % to 105 %. The tensile strength first increased and then declined, indicating that excessive irradiation leads to greater brittleness. Rheological measurements further showed two inflection points at 95  ℃ and 142  ℃ in the temperature sweep of the photocross-linked sample, directly evidencing distinct temperature responses associated with internal dynamic-imine bond exchange and depolymerization of the photocross-linked network, respectively. Stress-relaxation experiments revealed that, although the photocross-linked material retained a high modulus at elevated temperatures, the network gradually depolymerized at high temperatures (e.g., 160  ℃), transitioning the material into a viscous-flow state. These results demonstrate the multi-responsive capability of the dual-dynamic polymer network.