The Glass Transition of a Single Macromolecule

We employ molecular simulations to show that a generic isolated macromolecule behaves as a glass-forming liquid in an extreme state of nano confinement. Specifically, its glass transition temperature T-g is strongly suppressed with respect to a corresponding bulk-state polymer, but adsorption onto an attractive substrate can reverse this effect. Results indicate that observations of bulklike T-g in individual nanoconfined systems can result from a compensation point between T-g enhancement and T-g suppression. In addition to their implications for the understanding of nanostructured synthetic materials, these results are also likely relevant to the dynamics of globular and adsorbed biological macromolecules.