Entangled-like Chain Dynamics in Non-entangled Polymer Blends with Large Dynamic Asymmetry

TL;DR

This paper reveals that in non-entangled polymer blends with large dynamic asymmetry, the fast component exhibits entangled-like dynamics and non-exponential relaxation due to memory effects, challenging standard Rouse model predictions.

Contribution

It demonstrates that large dynamic asymmetry can induce entangled-like behavior in non-entangled polymer blends, highlighting the importance of memory effects in chain dynamics.

Findings

Fast component shows non-exponential Rouse mode relaxation.

Dynamic features resemble entangled chain behavior.

Memory effects break time uncorrelation assumptions.

Abstract

We discuss simulations of a simple model for polymer blends in the framework of the Rouse model. At odds with standard predictions, large dynamic asymmetry between the two components induces strong non-exponentiality of the Rouse modes for the fast component. Despite chains being much shorter than the entanglement length, it also induces dynamic features resembling a crossover to entangled-like chain dynamics. This unusual behavior is associated to strong memory effects which break down the assumption of time uncorrelation of the external forces acting on the tagged chain.