Ultra-stretchable chitin-based branched elastomers with enhanced mechanical properties via RAFT polymerization.

In this work, a chitin-based macromolecular chain transfer agent (Chitin-CTA) was designed to graft polymers from chitin at the molecular level. Homogeneous reversible addition-fragmentation chain transfer (RAFT) polymerization was performed to prepare branched MA elastomers, chitin-graft-poly(methyl acrylate) (Chitin-g-PMA) copolymers, which were thermally stable and showed tunable glass transition temperatures. These ultra-stretchable branched MA elastomers exhibit unique strain-hardening behavior and significantly enhanced mechanical properties. Mechanical tests indicate that the chitin backbones in branched MA elastomers can act as cross-linking points to improve the tensile strength, toughness, and elasticity simultaneously. The macroscopic performance of branched MA elastomers c be further promoted by introducing hydrogen bonding as non-covalent interaction to form an additional reversible physical network. This robust and versatile grafting strategy can provide new opportunities to prepare chitin-based branched MA elastomers with extraordinary mechanical properties.