Robust, reprocessable and shape-memory vinylogous urethane vitrimer composites enhanced by sacrificial and self-catalysis Zn(II)–ligand bonds

Abstract

Endowing thermoset polymers with reinforcement, reprocessability and multi-functions shows great potential in practice. Herein, we describe the facile synthesis of robust, healable and reprocessable aminated silica/polydimethylsiloxane (PDMS) composites by engineering dynamic vinylogous urethane crosslinks and sacrificial Zn(II)-amine coordination bonds into the matrix simultaneously. These dynamic dual cross-links are constructed not only between polymer chains but also on the interface of fillers and matrix due to the surface modification of silica. Vinylogous urethane crosslinks endow the vitrimers with good healing ability and reprocessability at elevated temperature, and Zn(II) ions could enhance the mechanical properties of composites significantly by sacrificial bonds. Besides, silica can further increase the energy dissipation ratio of sacrificial bonds. Furthermore, these Zn(II) ions could also act as Lewis acid catalysts to accelerate the exchange reactions of vinylogous urethane crosslinks and thereby improve the reprocessability and healable ability of PDMS composites. Moreover, the composites also had attractive shape-memory ability, showing great application potential in smart material fields.