4D printing of novel polybenzimidazole-containing structures with exceptional radiation resistance and mechanical properties

The 4D printing of high-temperature shape memory polymers (SMPs) has attracted tremendous interest because of its potential application in smart devices in the aerospace field. The development of SMPs with high thermal and mechanical properties as well as radiation resistance is challenging. In this work, we developed UV-curable resins based on rigid thermally stable poly-2,2′-( p -oxydiphenylene)-5,5′-dibenzimidazole (OPBI), a photosensitive solvent (N,N-dimethylacrylamide), and a crosslinker (bisphenol A ethoxylate diacrylate or tris [2-(acryloyloxy)ethyl] isocyanurate). 4D-printed high-performance SMPs were obtained through a UV‒thermal dual-curing process, which resulted in materials with high glass transition temperatures (155–185 °C) and increased tensile strengths (115–144 MPa). The combination of hard segments from OPBI and crosslinkers, as well as soft segments from N,N-dimethylacrylamide, results in excellent shape memory performance of the materials (the average shape fixity and shape recovery ratios both exceed 94 %). In addition, we found that 4D-printed OPBI-based SMPs are resistant to γ-radiation at doses up to 10^6 Gy. After γ-irradiation, the materials maintain high tensile strengths (up to 124 MPa), glass transition temperatures (up to 179 °C) and shape memory behavior. Thus, these new 4D-printed OPBI-based SMPs offer great potential for the aerospace industry.