Construction of high-performance, high-temperature shape memory polyimides bearing pyridine and trifluoromethyl group

Abstract

Shape memory polyimides (SMPIs) have gained considerable attention as smart deformation materials for their excellent properties. However, the relationship between shape memory performance and polyimide structure have hardly mentioned. Hence, three shape memory polyimides were manufactured with different structure monomers. Pyridine-contained polyimide (PI-1) and trifluoromethyl-contained polyimide (PI-3) were investigated by experimentally and molecular simulations on the physical properties and shape memory behaviors comparing with the benzene-structured polyimide (PI-2). Results showed that all polyimide films exhibited good thermal properties (TgDMA>258 °C). All PIs possessed great shape memory performances and stabilities. It was found that the introduction of pyridine group (PI-1) will restrict the tensile strain in dual-shape memory process of 155% but enhance the Rf and Rr of 99.7% and 93.7%, comparing with PI-2 of 256%, 99.8% and 89.2%, respective. Moreover, PI-3 with the presence of trifluoromethyl group can marked improve the elongation strain of 313%, in the meanwhile kindly reduce the Rr of 88.4%. Additionally, fractional free volume and storage modulus under high temperature provided simultaneous support for different shape memory performances. The current research may have specified a new way for the production and usage of the smart materials in practice.