ABA Block Copolyester Thiol–Ene Resin From Triethylborane-Assisted Ring-Opening Copolymerization

Leveraging metal-free ring-opening copolymerization catalyzed by a triethylborane and phosphazene base, we have developed a cytocompatible, thiol–ene-based block copolyester photoresin (BC1) with an ABA triblock architecture. A sebacate-derived polyester acting as the chain transfer agent improves the scalability of ring-opening copolymerization and enables the direct, facile synthesis of functional sebacate-derived polyesters by circumventing the conventional high-temperature polycondensation that will often destroy reactive functional groups. BC1's ABA block copolymer design enables tunable elasticity, and its surface property supports the proliferation of human umbilical vein endothelial cells better than polycaprolactone, a polyester with a well-established safety record. The polymerization approach presented in this work expands the potential of sebacate-derived materials and will inspire the development of more elastic photoresins that incorporate safe, renewable, and affordable feedstocks such as sebacic acid and other long-chain aliphatic carboxylic acids.