Glass transition of thin films of poly(2-vinyl pyridine) and poly(methyl methacrylate): nanocalorimetry measurements

Glass transitions were observed in thin films of poly(2-vinyl pyridine) (P2VP) and poly(methyl methacrylate) (PMMA) using a scanning nanocalorimetry technique which has both high sensitivity (10−9 J/K) and high scan rates (104–105 K/s). Samples were deposited by the spin-cast method. The thickness of samples was 100–400 nm. Glass transition temperature, obtained by nanocalorimetry, is shifted toward higher temperatures by 10–20 K and activation enthalpy of glass transition is shifted to lower values by factor of 2–4. The glass transition characteristics of both polymers are discussed in terms of the standard Tool–Narayanaswamy–Moynihan (TNM) multi-parameter model.