(560e) Loops, Links, and Bridges: Mechanical Properties of Triblock Copolymer Systems

Triblock copolymers find frequent use as thermoplastic elastomers. In these materials physical crosslinks in the form of discrete glassy domains composed by the polymer chain ends are bridged by a middle block with a much lower glass transition temperature. However, not all of the lower glass transition temperature chains contribute to the forming bridges in the network. Instead these other chains form loop structures in which both chain ends are part of the same glassy domain. These loop structures may either be noncontributing, or instead form links via two topologically connected loops which indirectly contribute to the material elastic properties. In this work using a simple coarse grained model, we quantify the relative number of linked loops in a model thermoplastic elastomer, as well as their contributions to the material's elastic response.