Motivated by recent experimental results on glassy polymer nanoparticles, we develop a minimal theoretical framework for the glass transition in spherical confinement. This is accomplished using our cooperative-string model for supercooled dynamics, that was successful at recovering the bulk phenomenology and describing the thin-film anomalies. In particular, we obtain predictions for the mobile-layer thickness as a function of temperature, and for the effective glass-transition temperature as a function of the radius of the spherical nanoparticle - including the existence of a critical particle radius below which vitrification never occurs. Finally, we compare the theoretical results to experimental data on polystyrene from the recent literature, and we discuss the latter.
@article{arxiv.1603.07539,
title = {Cooperative strings in glassy nanoparticles},
author = {Maxence Arutkin and Elie Raphaël and James A. Forrest and Thomas Salez},
journal= {arXiv preprint arXiv:1603.07539},
year = {2017}
}