Glass transition of polymer/single‐walled carbon nanotube composite films

Abstract

Abstract The glass‐transition temperatures ( T g 's) of nanocomposites of polystyrene (PS) and single‐walled carbon nanotubes were measured in the bulk and in thin films with differential scanning calorimetry and spectroscopic ellipsometry, respectively. The bulk T g of the nanocomposites increased by approximately 3 °C and became much broader than that of PS. For the nanocomposite films thinner than 45 nm, T g decreased with decreasing film thickness [i.e., Δ T g (nano) < 0]. This phenomenon also occurred in thin PS films, the magnitude of the depression in PS [Δ T g (PS)] being somewhat larger. The film thickness dependence and the differences in the magnitude of Δ T g in the two systems were examined in light of current theory, and a quantitative comparison was made. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3339–3345, 2003