Poly(p-dioxanone)-poly(ethylene glycol) network: synthesis, characterization, and its shape memory effect

Multi-shape polymers have recently attracted growing interest on account of their ability to switch between multiple shapes in a predetermined way. In this work, thermally induced shape-memory PPDO-PEG networks with well-defined architecture have been designed and prepared by coupling hydroxyl-telechelic three-arm star-shaped PPDO and PEG diol precursors with HDI in 1,2-dichloroethane. The molecular weight and the feed ratio of the two precursors affected the gel content and the cross-link density of the network. The DSC analysis indicated that increasing the content of a precursor, or its molecular weight, was helpful in enhancing the crystallization degree of its own domains. The testing of dual-shape and triple-shape effects of networks showed that composition and cross-link density played an important role. As a typical sample, PPDO(9k)(65)-PEG(6k)(35) exhibits a triple-shape effect, which possesses two separate and apparent melting endothermic peaks for the PPDO and PEG segments respectively.