Shape memory-assisted self-healing polyurethane inspired by a suture technique

Shape memory-assisted self-healing had attracted great research interests recently. In this work, inspired by a suture technique, a two-step shape memory-assisted self-healing polyurethane system based on the collaboration of disulfide bond and shape memory effect was proposed. The crack was first closed by shape memory effect, and then disulfide exchange reaction accelerated the chain interdiffusion and established linkages across the fractured surfaces to accomplish the healing of the mechanical properties. Structures of the prepared polyurethanes were confirmed by FTIR and Raman spectra. DSC implied that a certain level of poly(epsilon-caprolactone) diol molecular weight was needed to form a crystalline soft segment of polyurethane. Shape memory cycle and optical profiler observation indicated that a crystalline soft segment could lead to evident shape memory effect. Tensile test indicated that shape memory effect could promote healing efficiency and reduce healing time significantly. A maximal healing efficiency of about 97% could be achieved by a 1-h healing under 80 °C.