A Novel Route to Calculate the Length Scale for the Glass Transition in Polymers

TL;DR

This paper introduces a new method combining Adam-Gibbs theory and self-concentration to accurately determine the size of cooperatively rearranging regions in glass-forming polymers, revealing sizes of 1-3 nm at Tg.

Contribution

It presents a novel approach to calculate the CRR size in polymers by integrating theoretical models with experimental data, enabling precise quantification.

Findings

CRR size ranges from 1 to 3 nm at Tg

Method combines Adam-Gibbs theory with self-concentration

CRR size varies with polymer type

Abstract

The occurrence of glass transition is believed to be associated to cooperative motion with a growing length scale with decreasing temperature. We provide a novel route to calculate the size of cooperatively rearranging regions CRR of glass-forming polymers combining the Adam-Gibbs theory of the glass transition with the self-concentration concept. To do so we explore the dynamics of glass-forming polymers in different environments. The material specific parameter $\alpha$ connecting the size of the CRR to the configurational entropy is obtained in this way. Thereby, the size of CRR can be precisely quantified in absolute values. This size results to be in the range 1 $\div$ 3 nm at the glass transition temperature depending on the glass-forming polymer.