A series of near-infrared (NIR)-responsive shape memory polymers based on biphenyl epoxy (BPEP/GR) were prepared by mixed amine thermal curing and photocuring with an iodized salt photoinitiator and aromatic ferrocene photosensitizer (IOD/FC) initiator. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile test results indicated that the addition of graphene to a biphenyl-containing epoxy resin matrix led to improvements in the transition temperature, strength, and shape memory properties. Shape recovery could be completed within a few seconds by NIR irradiation due to the high photothermal conversion efficiency of graphene. NIR laser irradiation promoted the activation and recombination of biphenyl units due to local heating. Thus, a reconfigured shape was obtained. This new reconfiguration method is expected to help realize the important application of BPEP/GR composites in the field of intelligent soft robots.
The deformed BPEP/GR with a 3D structure rapidly recovered to a 2D film by remote NIR irradiation. Furthermore, because the crystal structure of the biphenyl unit can be regulated through rapid polymerization, thermal treatment is applicable. The activation and recombination of the biphenyl units and the NIR responsiveness results in the self-folding behavior of BPEP/GR under NIR laser irradiation. It is also recognized as a reconfigured permanent shape, which can be recovered under a thermal stimulus.