A Novel Temperature-Step Method to Determine the Glass Transition Temperature of Ultrathin Polymer Films by Liquid Dewetting

摘要

A novel temperature-step experimental method that extends the Bodiguel-Fretigny liquid dewetting method of investigating polymer thin films is described and results presented from an investigation of thickness effects on the glass transition temperature (T_g) of ultrathin polystyrene (PS) films. Unlike most other methods of thin film investigation,this,procedure promises a rapid screening tool to determine the overall profile of T_g versus film thickness for ultrathin polymer films using a limited number of samples. Similar to our prior observations and other literature data, with this new method obvious T_g depression was observed for PS thin films dewet- ting on both glycerol and an ionic liquid. The results for PS.dewetting on the two different liquids are similar indicating only modest effects of the substrate on the T_g-film thickness- relationship, In both instances, the T_g depression is somewhat less than for similar PSs supported on silicon substrates reported in the literature.