Study on the thermal-induced shape memory effect of pyridine containing supramolecular polyurethane

In this paper, a series of pyridine containing supramolecular polyurethanes (PUPys) were synthesized from BINA, HDI and BDO. Then the structure, morphology and thermal-induced shape memory effect (SMEs) of PUPys were investigated systematically. Results show that strong hydrogen bonding is formed in the urethane group as well as in the pyridine ring; and phase separation consisting of soft phase and hard phase occurs in the PUPy. In addition, it is found that the lower limit of BINA content for PUPys exhibiting good SMEs is 30 wt%. PUPys with higher BINA content show higher shape fixity, higher shape recovery and better strain stability. Moreover, the shape recovery force increases with the decreasing of BINA content. Finally, the temperature-dependent FT-IR spectra support that the hydrogen bonding in the pyridine ring serves as the molecular switch; while the hydrogen bonding in the urethane groups acts as the physical netpoints for the utilization of PUPys as SMMs.