Organic–Inorganic Polycyclooctadienes with Double-Decker Silsesquioxanes in the Main Chains: Synthesis, Self-Healing, and Shape Memory Properties Regulated with Quadruple Hydrogen Bonds

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Double-decker silsesquioxane (DDSQ) cages were introduced into the main chains of polycyclooctadiene via a ring-opening metathesis polymerization (ROMP) approach. Toward this end, a macromolecular chain transfer agent for the ROMP was synthesized via acyclic diene metathesis polymerization of 3,13-diallyl DDSQ with the Grubbs second catalyst. To regulate the intermolecular specific interactions, 4-(2-hydroxyethyl)-10-oxa-4-azatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione-2-ureido-4[1 H ]-pyrimidinone was synthesized and used as a monomer of copolymerization. It was found that the organic–inorganic copolymers were heterogeneous at the nanometer scale. The POSS ( viz., DDSQ) cages were aggregated into the POSS nanophases with the size of 20–30 nm. The POSS microdomains behaved as the netpoints of physically cross-linked networks and thus the organic–inorganic copolymers can display the behavior of cross-linked elastomers. As a result of the physical crosslinking, the organic–inorganic copolymers possessed shape memory properties. Meanwhile, the materials possessed excellent self-healing properties and plasticity in solids with the quadruple hydrogen bonds with 2-ureido-4[1 H ]-pyrimidinone groups. While the organic–inorganic copolymers were used as shape memory materials, their original shapes can be reprogrammed by the use of the plasticity in solids of the materials.