Is there a higher-order Mode Coupling transition in polymer blends?

Abstract

We present simulations on a binary blend of bead-spring polymer chains. The introduction of monomer size disparity yields very different relaxation times for each component of the blend. Competition between two different arrest mechanisms, namely bulk-like dynamics and confinement, leads to an anomalous relaxation scenario for the fast component, characterized by sublinear time dependence for mean squared displacements, or logarithmic decay and convex-to-concave crossover for density-density correlators. These anomalous dynamic features, which are observed over time intervals extending up to four decades, strongly resemble predictions of Mode Coupling Theory for nearby higher-order transitions. Chain connectivity extends anomalous relaxation over a wide range of blend compositions.

Published in Journal of Chemical Physics 124 (2006) 184906

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• Molecular dynamics simulations of glassy polymers
• Relaxation Scenarios in a Mixture of Large and Small Spheres: Dependence on the Size Disparity
• Anomalous Dynamic Arrest in a Mixture of Big and Small Particles
• Mode-coupling theory for the slow collective dynamics of fluids adsorbed in disordered porous media
• Logarithmic decay in single-particle relaxations of hydrated lysozyme powder
• Entangled-like Chain Dynamics in Non-entangled Polymer Blends with Large Dynamic Asymmetry
• The Role of Intramolecular Barriers on the Glass Transition of Polymers: Computer Simulations vs. Mode Coupling Theory
• Atomic motions in the $\alpha \beta$-region of glass-forming polymers: Molecular versus Mode Coupling Theory approach
• Tests of mode coupling theory in a simple model for two-component miscible polymer blends
• Logarithmic Relaxation in a Kinetically Constrained Model
• Dynamic structure factor of a stiff polymer in a glassy solution
• Slow dynamics coupled with cluster formation in ultrasoft-potential glasses
• Static and dynamic contributions to anomalous chain dynamics in polymer blends
• Postponing the dynamical transition density using competing interactions
• Anomalous relaxation in binary mixtures: a dynamic facilitation picture