Eur. Phys. J. E (2003) 12: 103-107
https://doi.org/10.1140/epjed/e2003-01-024-2

Glass transition temperature of freely-standing films of atactic poly(methyl methacrylate)

Department of Physics and the Guelph-Waterloo Physics Institute, University of Guelph, Guelph, Ontario, N1G 2W1, Canada

^* e-mail: dutcher@physics.uoguelph.ca

Received: 1 January 2003
Published online: 5 November 2003

Abstract

We have used ellipsometry to measure the glass transition temperature T _g of high molecular weight (M _w =790 × 10³), freely-standing films of atactic poly(methyl methacrylate) (a-PMMA), as well as films of the same polymer supported on two different substrates: the native oxide layer of silicon (Si) and gold-covered Si. We observe linear reductions in T _g with decreasing film thickness h for the freely-standing PMMA films with 30 nm <h<100 nm, which is qualitatively similar to previous results obtained for freely-standing polystyrene (PS) films. However the magnitude of the T _g reductions for PMMA is much less than for freely-standing films of PS of comparable molecular weight and thickness. We also find that for films supported on either substrate, with thicknesses as small as 30 nm, the T _g values do not deviate substantially from the value measured for thick films.