Synthesis and Functionalization of Cross-Linking Macroinimers for Photocurable Systems

Abstract

Hyperbranched prepolymers (HBPs) bearing acrylate functionalities were functionalized via photoiniferter RAFT (PI-RAFT) block copolymerization using multifunctional acrylates. By controlling the reagent functional group concentrations, the oligomer size was controlled, while pendant double bonds were efficiently added over short time periods. Throughout the reaction, three competing pathways, namely, functionalization, internal cyclization, and combination, were identified along with their dependence on HBP size. The ability to simultaneously initiate and cross-link photopolymer networks was subsequently investigated by placing functionalized HBPs in the presence of a monofunctional reactive diluent. Additionally, 3D-printed structures were formed using HBPs as cross-linking agents, resulting in the formation of elastomeric structures. This study demonstrates that acrylate-functional oligomers can be designed and synthesized using facile and rapid PI-RAFT copolymerization and subsequently used to both cross-link and initiate photopolymer materials.