The Glass Transition of a Single Macromolecule

Published

September 21, 2016

Author(s)

Jack F. Douglas, David Simmons, Weston L. Merling, Jack Mileski

Abstract

The glass transition of a single macromolecule in isolation is relevant to the dynamics of systems including dilute solutions of synthetic polymers and biological macromolecules such as proteins. Here we employ molecular dynamics simulation to show that a generic isolated macromolecule in vacuum behaves as a glass-forming liquid in an extreme state of nanoconfinement. Specifically, the glass transition temperature Tg of this isolated chain is strongly suppressed with respect to the bulk melt state; however, absorption of this chain onto a substrate can reverse this effect, yielding a weaker Tg suppression or even a Tg enhancement. These results provide new insights into the glass transition of confined materials and dilute macromolecule solutions and indicate that the dynamics of dilute globular biological macromolecules should generally be suppressed upon adhesion to a substrate. We conclude that observations of bulk-like Tg in individual supported polymer systems cannot be used to draw conclusions regarding nanoconfinement effects in general, due to the possibility that the system inhabits a ‘compensation point’ between Tg-enhancement and Tg-suppression.

Citation

Macromolecules

Pub Type

Journals

Keywords

polymer chain, protein, globule, glass formation, polymer-surface interaction, compensation point

Citation

Douglas, J. , Simmons, D. , Merling, W. and Mileski, J. (2016), The Glass Transition of a Single Macromolecule, Macromolecules (Accessed May 19, 2024)