Paper Number
SM13 

Session
Polymers Solutions, Melts and Blends

Title
Theory of interchain packing and the interplay of caging and physical bonding on segmental relaxation and shear elasticity in associating copolymer liquids

Presentation Date and Time
October 21, 2019 (Monday) 5:00

Track / Room
Track 3 / Room 201

Authors (Click on name to view author profile)

1. Ghosh, Ashesh (University of Illinois at Urbana-Champaign, Department of Chemistry)
2. Schweizer, Kenneth S. (University of Illinois at Urbana-Champaign, Department of Materials Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Ashesh Ghosh¹ and Kenneth S. Schweizer^2
1Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, IL 61820; ²Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801

Speaker / Presenter 
Ghosh, Ashesh

Text of Abstract
We employ liquid state statistical mechanical theory to elucidate the role of attractive groups regularly co-polymerized in a chain backbone on the intermolecular packing structure and activated dynamics of unentangled polymer liquids that can form thermo-reversible bonds. Coarse-grained polymer physics models of the macromolecular scale dynamics and mechanics of transient networks typically adopt several key parameters determined by local physics such as the alpha relaxation time and sticker association lifetime and bond strength as phenomenological input. Our aim is to predict how the latter are determined from microscopic interchain forces, sticker clustering and packing correlations. This problem is addressed by combining equilibrium polymer integral equation (PRISM) theory and non-linear Langevin equation based dynamical methods that capture steric caging and physical bond formation to construct the dynamic free energies of sticker and non-sticker groups which control segment scale stochastic trajectories. Knowledge of this local physics allows the calculation of the high frequency elastic shear modulus due to interchain stresses, and the dynamic transient localization lengths, barriers and activated relaxation times for stickers and non-stickers. How these properties vary with polymer volume fraction or temperature, fraction of stickers, strength and spatial range of the attractive interaction, and chain length has been studied. Of particular interest is how non-sticker local hopping events (alpha process) are perturbed by sticky group clustering and bond formation, and the degree to which the sticker unbinding process is coupled with non-sticker segmental relaxation. Results for a limiting strong association case will also be presented based on an idealized partially pinned homopolymer model.