Reversibility in glass transition behavior after erasing stress induced by spin coating process
Résumé
The influence of the sample preparation on the observed dependence of glass transition temperature (T-g) with thickness in polystyrene (PS) thin films has been investigated. Spectroscopic ellipsometry was used to measure the T-g of PS thin films ranging from 7 to 85 nm before and after exposition to supercritical carbon dioxide (sc-CO2). We take advantage of the sc-CO2 properties along with thermal annealing treatment to cancel out sample preparation history factor by removing the remnant solvent and residual stresses. The decrease in T-g shows exactly the same trend before and after sc-CO2 exposure plus thermal treatment. This result cancels out the influence of the spin coating process on the T-g depression in thin films. (C) 2017 Elsevier Ltd. All rights reserved.