Programmable Biodegradation of Photo-Cross-Linked Poly(trimethylene carbonate) Elastomers via Competitive Thiol–ene Click Chemistry

Cross-linked poly(trimethylene carbonate) (PTMC) elastomers are widely explored as soft, resorbable implants, yet their dense networks render degradation slow and uncontrollable, limiting predictable clinical performance. This study addresses the long-standing challenge of endowing PTMC elastomers with both structural integrity and controllable, on-demand biodegradation. Methacrylate-terminated PTMC oligomers of varied degrees of polymerization were synthesized and photo-cross-linked in the presence of 1,6-hexanedithiol (HDT). Acting as a competing cross-linker via thiol-ene click chemistry, HDT systematically relaxed the radical-polymerized network. The resulting elastomers exhibited linear surface erosion both in vitro and in vivo, with rates tunable over 1 order of magnitude by varying HDT content while maintaining excellent dimensional stability, achieving degradation levels comparable to medium-molecular-weight linear PTMC. Unlike previous methods that relied solely on radical polymerization or γ irradiation, this supplementary thiol-ene click chemistry-based competition strategy in photo-cross-linking enables direct, quantitative control over cross-linking density and degradation rate of PTMC elastomers. This work establishes a practical platform for fabricating implantable photo-cross-linked PTMC devices with programmable resorption timelines, expanding opportunities for customized drug delivery depots and mechanically matched devices.