Waterborne Biodegradable Polyesters Based on Thiol–Ene Chemistry for Paper Coating Applications

Thiol-ene chemistry using ester-containing monomers offers a promising route to biodegradable polymers for sustainable packaging in order to improve the compostability or recyclability of coated paper. This study focuses on the synthesis of thiol-ene latexes via emulsion and miniemulsion polymerization, targeting waterborne paper coating applications. The process provides key advantages, including efficient film formation and compatibility with industrially scalable conditions through semibatch emulsion and swelling-assisted polymerization, which improve control over particle size and crosslinking. Among the tested formulations, the diallyl adipate/2,2'-(ethylenedioxy)-diethanethiol/trimethylolpropane tris-(3-mercaptopropionate) system demonstrates superior performance, forming transparent, nontacky films with good water and oil resistance, critical indicators for paper coating functionality. Biodegradability tests confirm partial degradation, supporting the environmental benefits of these materials. Overall, the results highlight ester-containing thiol-ene emulsions as viable platforms for sustainable, high-performance paper coatings in packaging applications.