Highly crosslinked, ultra-hard networks from polymer combs

Comb polymers are branched macromolecules used as compatibilizers, surface modifiers, and, when polymerized, as strong networks. Comb polymers are typically synthesized to contain different backbone and sidechain chemistries, which can result in multifunctional reactivity and strong phase separation from different polymer domains. Here, we explored designing comb polymers that could result in high modulus, tough networks by synthesizing polymers with glycidyl methacrylate sidechains capable of participating in dense crosslinking reactions. We synthesized several comb polymers containing homopolymer, block, or random copolymer sidechains, and compared their mechanical properties and network structures to their linear counterparts. Comb polymers with random copolymer side chains had superior toughness, even compared to their linear counterparts. We hypothesize that statistical distribution of monomers along the grafts break up crosslinking sites, disfavoring intramolecular crosslinks and favor intermolecular crosslinks. We expect these polymers to be useful for multi-functional coatings and as adhesives with high modulus and toughness.