Nanometer Scale Dielectric Fluctuations at the Glass Transition

TL;DR

This study uses advanced microscopy to observe nanometer-scale dielectric fluctuations near the glass transition in PVAc, revealing heterogeneous, cooperative regions and their dynamics through noise analysis.

Contribution

It provides direct experimental evidence of nano-scale heterogeneity and cooperative regions at the glass transition using non-contact SPM techniques.

Findings

Detection of 1/f noise from thermal polarization fluctuations

Identification of cooperative nano-regions with heterogeneous kinetics

Determination of the cooperative length scale

Abstract

Using non-contact scanning probe microscopy (SPM) techniques, dielectric properties were studied on 50 nanometer length scales in poly-vinyl-acetate (PVAc) films in the vicinity of the glass transition. Low frequency (1/f) noise observed in the measurements, was shown to arise from thermal fluctuations of the electric polarization. Anomalous variations observed in the noise spectrum provide direct evidence for cooperative nano-regions with heterogeneous kinetics. The cooperative length scale was determined. Heterogeneity was long-lived only well below the glass transition for faster than average processes.