Synthesis and Properties of Reversible Disulfide Bond-based Self-healing Polyurethane with Triple Shape Memory Properties

A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone)(PCLA),hexamethylene diisocyanate (HDI),polytetrahydrofuran(PTMEG),and 4,4'-aminophenyl disulfide.The chemical structures were characterized using~1H nuclear magnetic resonance (~1H-NMR)spectroscopy,Fourier transform infrared spectroscopy (FTIR),and gel permeation chromatography (GPC).The thermal properties,selfhealing properties,triple-shape memory effect,and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC),tensile tests,two-step programming process thermal mechanical experiments,and subsequent progressive thermal recovery.The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler.It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 500C (with shape fixation ratios of 94.3%and 98.3%,shape recovery ratios of 76.6%and 85.1%,respectively) were integrated to the shape memory polyurethane.As-prepared polyurethane is expected to have potential applications in multi-shape coatings,films,and step-by-step deploying structures.