A simple and unified model, free of any adjustable parameters, is developed
for the finite size effect on glass transition temperatures of polymers an
d organic particles. As the thickness of polymer thin films and the radius
of organic particles decrease, their glass transition temperatures decrease
. For polymers, this decrease is independent of their molecular weight, but
dependent on the correlation length for intermolecular cooperative rearran
gement and the presence of substrates. The model predictions are consistent
with available experimental results on size dependence of the glass transi
tion temperatures for free-standing polystyrene thin films, polystyrene fil
ms supported on passivated substrates and o-terphenyl and benzyl alcohol na
noparticles. (C) 1999 Elsevier Science S.A. All rights reserved.