Abstract. On the basis of the nanoscale fluctuations of the excess number density of holes (free volumes), a theoretical model is developed to describe the glass transition temperature (T_g) of polymeric films with the thickness < 100 nm. A Langevin equation is used in the derivation that helps us to understand the dependence of T_g not only on film thickness but also on molecular weight. Substrates have a strong influence on T_g and the diffusion coefficient of nanofilms, and the surface concentration of adsorbed chain ends depends on the strength of polymer-substrate interactions.

Print publication: Issue 19 (20 May 2002)
Received 13 February 2002
Published 2 May 2002