Controlling network structure and thermomechanical properties of photopolymerized networks through prepolymer architecture

Allan Guymon, University of Iowa

Abstract: This work examines how prepolymer architecture, specifically reactive group placement, leads to structure property relationships concerning network formation in photocurable systems. Nitroxide mediated polymerization (NMP) and Reversible addition-fragmentation chain transfer (RAFT) was used to synthesize prepolymers with photocurable groups located predominantly at the chain ends or in the middle of large prepolymers. The presence of homo-butyl acrylate between the end-functionalized prepolymers induced the formation of multiple domains within the network compared to a randomly functionalized control. The presence of both high and low T g domains within the polymer networks produced materials with significant increases in Young’s modulus while maintaining a high elongation at break. End functionalized materials also increase creep resistance and provides a facile method of targeting different thermomechanical properties without altering the chemical composition of a photocurable formulation.