Thermorheological Complexity in Polymers and the Problem of the Glass Transition

TL;DR

This paper discusses the differences between dynamic heterogeneities and thermorheological complexity in polymers, emphasizing that the latter involves distinct mechanisms and cannot be explained by averaging over different scales.

Contribution

It clarifies that thermorheological complexity in polymers is driven by mechanisms different from those of dynamic heterogeneities related to the glass transition.

Findings

Thermorheological complexity involves mechanisms distinct from dynamic heterogeneities.

Averaging over scales does not resolve thermorheological complexity.

Different properties of chain dynamics reflect separate underlying processes.

Abstract

A current focus in studies of the glass transition is the role of dynamic heterogeneities. Although these efforts may clarify the origin of the spectacular change in properties of liquids approaching vitrification, we point out that a seemingly related phenomenon, thermorheological complexity in polymers, must involve different mechanisms. In particular, as seen from consideration of various properties involving the chain dynamics, averaging over different length and time scales cannot offer a resolution to the problem of thermorheological complexity.