Spinodal Surface Fluctuations on Polymer Films

TL;DR

This paper investigates surface fluctuation growth in unstable polymer films, revealing that large-amplitude fluctuations from homogeneous nucleation cause deviations from mean-field theory predictions.

Contribution

It demonstrates the significance of homogeneous nucleation-induced fluctuations in spinodal surface instability, extending beyond traditional thermal noise models.

Findings

Mean-field theory accurately predicts growth rates in deep spinodal region.

Deviations occur as film instability decreases and are due to nucleation-induced fluctuations.

Homogeneous nucleation effects are crucial for understanding surface dynamics in polymer films.

Abstract

We study the temporal growth pattern of surface fluctuations on a series of spinodally unstable polymer films where the degree of instability is controlled by the film thickness. For films in the deep spinodal region, the growth rate function of the surface modes as a function of the wavevector,, fits well to the mean-field theory. As the film thickness is increased and the film instability decreases, the mean-field theory demonstrates marked disagreement with experiment, notwithstanding provision of the known corrections for random thermal noise. We show that the deviations arise from large-amplitude fluctuations induced by homogeneous nucleation, which has not been considered in conventional treatment of thermal noise.