Enhancing the Thermomechanical Properties of Photopolymer Networks Using Small-Molecular-Weight Hyperbranched Prepolymer Additives

Photoiniferter RAFT polymerization was utilized to synthesize and functionalize small-molecular-weight hyperbranched prepolymers (HBPs). HBPs were incorporated in densely cross-linking photocurable systems to investigate the impact of their size and structure on resin and material properties. The incorporation of HBPs induced a significant reduction in viscosity, enhanced network homogeneity, and increased material toughness compared to linear prepolymer counterparts. When shrinkage stress was normalized using the Young’s modulus of the final network, lower shrinkage stresses were observed for HBP-modified systems, especially when functionalized with pendant acrylate groups. In comparison to commercial linear urethane diacrylate cross-linkers, the HBP-modified network showed significantly enhanced network homogeneity and mechanical toughness. This study demonstrates that HBPs enable access to reduced resin viscosity and shrinkage stress as well as enhanced network homogeneity compared to conventional linear oligomer additives in densely cross-linked photocurable systems.