Thermomechanical activation achieving orthogonal working/healing conditions of nanostructured tri-block copolymer thermosets

Abstract

Conventional thermosets, despite their technological significance in today’s materials economy, present a modern sustainability challenge because of their lack of end-of-life options for recyclability or reprocessability. Emerging covalent adaptable networks (CANs) offer sustainable alternatives to permanently crosslinked materials, but ideal orthogonal working/reprocessing conditions are hardly achievable by the current thermochemical activation mechanism. Here we report a CAN system of additive/catalyst-free, fully reprocessable, crosslinked, tri-block copolymer (tri-BCP) thermoplastic elastomer networks based on acid-anhydride bond exchange operated on a thermomechanical activation mechanism. The unique functionality of the tri-BCP architecture enables self-assembly into inter-linked, hexagonally packed cylinder nanostructures that preclude any productive inter-cylinder bond exchange (and, thus, creep) without cooperative thermal and mechanical (heating and compression) processing conditions. Tri-BCP assembly into additive-free, inter-linked hexagonally packed cylinder networks Healable crosslinked networks via thermomechanical-induced inter-domain bond exchange Working conditions restrict creep, establishing orthogonal working/healing behavior Clarke et al. show crosslinked tri-block copolymers with nanostructured networks, constructed by a catalyst/additive-free self-crosslinking and self-assembly process. Compared with analogous random and di-block copolymers, these crosslinked tri-block copolymers show not only superior mechanical performance but also much greater creep resistance when operated on a morphology-regulated and thermomechanical activation mechanism.