Physical Bond Breaking in Associating Copolymer Liquids

We combine ideas from polymer and glassy liquid physics to construct a new model for the bond-breaking time scale of attractive sticker groups in associating copolymer liquids that form transient networks. The activated event is argued to be a two-step process, involving first the release of the nonsticker dynamic caging constraints that defines the primary alpha relaxation, followed by attractive stickers surmounting an association free-energy barrier subject to a local frictional resistance which can be strongly affected by relaxation-diffusion decoupling. The ideas embedded in the model produce a consistent and good description of the bond-breaking time scale for diverse polymer chemistries and architectures as a function of temperature and fraction of sticky groups. Chemically sensible values for association free energies are deduced. In strong contrast, the existing phenomenological models are shown to incur qualitative failures.

Automated summary

By combining concepts from polymer and glassy liquid physics, a new model has been constructed to describe the bond-breaking time scale of attractive sticker groups in associating copolymer liquids. The model suggests that the activated event is a two-step process involving the release of dynamic caging constraints and the attractive stickers surmounting a free-energy barrier. This model provides a consistent description for diverse polymer chemistries and architectures, while existing phenomenological models show qualitative failures.