Organic–Inorganic Linear Segmented Polyurethanes Simultaneously Having Shape Recovery and Self-Healing Properties

Double-decker silsesquioxane (DDSQ) and hindered urea bonds were simultaneously introduced into the main chains of linear segmented polyurethane (PU) to synthesize organic–inorganic linear segmented poly(urea urethanes) (PUUs). The organic–inorganic PUUs were microphase-separated, and the POSS cages were aggregated into the microdomains with the size of 10–20 nm. The organic–inorganic PUUs had the improved thermomechanical properties in comparison to those of the control PU. Notably, the strong physical cross-linking was formed in the organic–inorganic PUUs, and thus the materials could display the properties of thermoset elastomers. The physical cross-linking was attributable to the formation of POSS microdomains, which acted as the nano-cross-linking sites. Owing to the formation of physical cross-linking, the shape memory properties have been imparted to the organic–inorganic nanocomposites; the fixing of temporary shapes and the recovery of original shapes were significantly improved. The inclusion of hindered urea bonds provided the organic–inorganic PUUs with the solid-state plasticity at room temperature (i.e., self-healing properties) via the dynamic exchange of hindered urea bonds. It was found that the nanoreinforcement of POSS microdomains did not significantly decrease the self-healing properties of the organic–inorganic PUUs. This work reports an approach simultaneously to optimize the shape memory and self-healing properties of polyurethanes.