4D-printing of mechanically durable high-temperature shape memory polymer with good irradiation resistance

4D-printed shape memory polymers (SMPs) are of great interest in the aerospace industry. However, development of high-temperature SMPs that combine high mechanical characteristics and radiation resistance remains challenging. Here, we report a new photosensitive composition (PSC) based on high-performance thermally stable poly-N,N'-(m-phenylene)isophthalamide (MPA), rigid photopolymerizable tris[2-(acryloyloxy)ethyl] isocyanurate (TAI), and a reactive solvent (N,N-dimethylacrylamide (DMAA)). The resulting PSC was utilized to prepare high-temperature SMPs using a facile two-step LCD 3D-printing and thermal post-curing process. The synergy effect between rigid backbones of MPA and TAI results in the highest reported tensile strength (104.4 ± 6.2 MPa) and glass transition temperature (180°C) of 4D-printed SMPs. The presence of soft segments from DMAA results in a good shape memory performance (shape fixity and shape recovery ratios both exceed 99%). Furthermore, this is the first comprehensive study of the influence of ionizing radiation on the performance characteristics of 4D-printed materials. It was shown that a 4D-printed SMP has endured γ-radiation with doses up to 10^6 Gy with the chemical structure, glass transition temperature, thermal stability, and shape memory behavior remaining virtually unchanged. In addition, MPA-based materials keep high tensile strengths (> 100 MPa) and elongations at break (> 5%) after being irradiated. With the high glass transition temperature, record-high tensile strength, excellent irradiation resistance, and 4D-printability, this new high temperature SMP shows great potential in deployable space structures application.

Smart materials; shape memory polymers; LCD 4D-printing; aromatic polyamide; γ-radiation.