Sustainable fluorescent elastomers derived from chitin and coumarin through grafting polymerization

Sustainable and functional elastomers derived from renewable resources are highly desirable as alternatives to conventional petroleum-based materials. Herein, a series of chitin-based fluorescent elastomers, Chitin- graft -poly(7-acryloyloxy-4-methyl coumarin- co - n -butyl acrylate) (Chitin-g-P(AMC- co -BA)) copolymers, were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. In this design, the coumarin derivative AMC was used as the hard and fluorescent segment while BA was selected as the soft segment to graft from the rigid chitin backbone to construct novel bio-based elastomers. By systematically varying the AMC/BA feed ratios and chitin contents, the glass transition temperature ( T g ), mechanical performance, adhesion strength, and fluorescent properties of the Chitin-g-P(AMC- co -BA) could be precisely tailored. The elastomers demonstrated tunable tensile strength (up to 12.2 MPa) and extensibility (up to 1989%). Furthermore, these chitin graft copolymers possess excellent adhesion performance and show strong blue fluorescence under UV irradiation, benefiting from the presence of the coumarin structure. This work provides an effective grafting strategy to develop multifunctional, sustainable elastomers from chitin and bio-based monomers, offering promising potential for applications in adhesives, flexible materials, and fluorescent functional systems.