Shape Memory and Self-Healing Nanocomposites with POSS–POSS Interactions and Quadruple Hydrogen Bonds
Sen Xu, Bingjie Zhao, Mohsin Raza, Lei Li, Huaming Wang, Sixun Zheng
Abstract
The organic–inorganic nanocomposites were constructed via polyhedral oligomeric silsesquioxanes (POSS)–POSS interactions and supramolecular quadruple hydrogen bonds. First, a double-decker silsesquioxane (DDSQ) was functionalized with two trithiocarbonate groups. Thereafter, the functionalized DDSQ was used to mediate the radial copolymerization of butyl acrylate (BA) with 2-ureido-4[1H]-pyrimidinone acrylate (UPyA). The reversible addition–fragmentation chain transfer (RAFT) polymerizations afforded the organic–inorganic hybrids with the architecture that a single POSS cage was embedded in the middle of a P(BA-co-UPyA) copolymer chain. The morphological investigation showed that the organic–inorganic hybrids were microphase-separated; the POSS (viz., DDSQ) cages were aggregated into the microdomains with diameter 10–20 nm. It was found that the organic–inorganic nanocomposites simultaneously had shape memory and self-healing properties. The shape memory and self-healing properties can be regulated with the supramolecular quadruple bonding interactions. The shape memory properties are attributable to the formation of physical cross-linking in the materials, whereas the self-healing properties are responsible for the introduction of dynamic noncovalent bonds (viz., quadruple hydrogen bonds). The self-healing properties can be utilized to reprogram the original shapes of the shape memory nanocomposites.