4D-printing of high-temperature shape-memory polymers based on polyimide, N,N-dimethylacrylamide and photoactive cross-linkers

Abstract

Thermally responsive shape memory polyimides (PIs) have attracted significant attention in the high-tech fields like aerospace industry. At the same time creating of materials and approaches to the formation of three-dimensional (3D) shape memory structures containing PIs remains an urgent task. In this work we have developed new photopolymeric compositions (PPCs) based on high-performance readily soluble PI, reactive solvent (N,N-dimethylacrylamide) and photoactive cross-linker (bisphenol A ethoxylate diacrylate (BAEDA) or tris[2-(acryloyloxy)ethyl] isocyanurate (TAI)). The resulting PPCs were used to form 3D-structures using LCD 3D-printing. It has been found that the nature of the cross-linker and post-processing temperature have a significant impact on the thermal and mechanical properties of the materials. The tensile strength has the maximum value after the thermal post-curing at 250°С for 1 h (83.3 ± 7.4 MPa and 60.8 ± 4.8 MPa for PPCs with TAI and BAEDA, respectively). Moreover, 4D-printed PI-containing materials exhibit an excellent shape memory performance at recovery temperatures >150 °C, with shape fixity ratio >99% and shape recovery ratio up to 95.6%.