Mechanical and Structural Consequences of Associative Dynamic Cross-Linking in Acrylic Diblock Copolymers
Jacob S. A. Ishibashi, Ian C. Pierce, Alice B. Chang, Aristotelis Zografos, Bassil M. El-Zaatari, Yan Fang, Steven J. Weigand, Frank S. Bates, Julia A. Kalow
Abstract
The composition of low-Tg n-butylacrylate-block-(acetoxyaceto)ethyl acrylate block polymers is investigated as a strategy to tune the properties of dynamically cross-linked vinylogous urethane vitrimers. As the proportion of the cross-linkable block is increased, the thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence is presented that network connectivity defects such as loops and dangling ends are increased by microphase separation. The thermomechanical and viscoelastic properties of block-copolymer-derived vitrimers arise from the subtle interplay of microphase separation and network defects.