Microscopic Theory of the Role of Strong Attractions on the Local Dynamics and Elasticity of Associating Copolymer Liquids

We construct a microscopic liquid state theory for how attractions between sticky groups regularly co-polymerized in a chain backbone affect local structure and dynamics of unentangled polymer liquids. Based on the bare attractive interaction and single-chain structure as input, PRISM integral equation theory is combined with activated dynamics approaches that capture caging and physical bond formation to study emergent high frequency elasticity and local relaxation processes. The dynamic free energies and corresponding sticker and non-sticker barrier hopping timescales that define the coupled bond breakage and cage escape processes are predicted within a 2-step dynamical scenario that applies in the strong attraction regime. The first step involves non-sticker hopping (alpha process) which is perturbed due to physical bonds between sticky segments that act as pinning constraints. After the non-sticker hops, the dynamical constraints and friction experienced by the sticky groups are renormalized and activated bond-breaking defines the second step. We present representative results for structure and dynamics as a function of sticker fraction, strength and range of the attraction, density, and temperature. Connections between dynamics and equilibrium properties are identified.