Intrinsically Re-curable Photopolymers Containing Dynamic Thiol-Michael Bonds

• Published in: Journal of the American Chemical Society Vol. 144; no. 26; pp. 11729 - 11735
• Main Authors: Stubbs, Connor J., Khalfa, Anissa L., Chiaradia, Viviane, Worch, Joshua C., Dove, Andrew P.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06.07.2022
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.2c03525

The development of photopolymers that can be depolymerized and subsequently re-cured using the same light stimulus presents a significant technical challenge. A bio-sourced terpenoid structure, l-carvone, inspired the creation of a re-curable photopolymer in which the orthogonal reactivity of an irreversible thioether and a dynamic thiol-Michael bond enables both photopolymerization and thermally driven depolymerization of mechanically robust polymer networks. The di-alkene containing l-carvone was partially reacted with a multi-arm thiol to generate a non-crosslinked telechelic photopolymer. Upon further UV exposure, the photopolymer crosslinked into a mechanically robust network featuring reversible Michael bonds at junction points that could be activated to revert, or depolymerize, the network into a viscous telechelic photopolymer. The regenerated photopolymer displayed intrinsic re-curability over two recycles while maintaining the desirable thermomechanical properties of a conventional network: insolubility, resistance to stress relaxation, and structural integrity up to 170 °C. Our findings present an on-demand, re-curable photopolymer platform based on a sustainable feedstock.