Poly(lactic acid)/polycaprolactone-based self-programmed photothermal responsive shape memory polymers

Shape memory polymers, based on their unique property that they can automatically revert to their original shape after deformation when subjected to external stimuli, have shown great application prospects and practical value in many fields such as aerospace, automotive and biomedical in recent years. In this study, poly(lactic acid) (PLA)/polycaprolactone (PCL) is used as a substrate, and a graft product, PLA-g-GMA, is prepared by grafting glycidyl methacrylate (GMA) onto PLA as a compatibilizer, and then polymer substrates are prepared by melt extrusion. Then, light-responsive shape memory composites are prepared by loading polypyrrole (PPy) nanoparticles with photothermal conversion functionality into the PLA/PCL substrate, and PPy-coated NdFeB (PPy@NdFeB) is used as the functional phase to prepare auto-responsive shape memory polymers that can be programmed automatically. Among them, the PLA/PCL/PPy composites show shape recovery rate (R_r) and shape fixation rate (R_f) of 81.11% and 98.87%, respectively, at a strain of 85.27% under the programming conditions of a deformation temperature of 65 °C and a stress of 2.14 MPa. The PLA/PCL/PPy@NdFeB composite material, in addition to excellent double and triple shape memory behavior, also has obvious magnetic properties, which can be used to carry out self-programmed temporary shapes. This research aims to solve the limitations of temperature-responsive shape memory polymers in a single stimulus response mode, broaden their application scope, further promote the development of shape memory polymers, and provide realistic guidance for the field of 4D printing.