Glass transition and dynamics of single and stacked thin films of poly(2-chlorostyrene)

The glass transition temperature and the dynamics of the α-process have been investigated using dielectric relaxation spectroscopy for single and stacked thin films of poly(2-chlorostyrene) (P2CS). The stacked film consists of 10 layers of single thin films with thickness of 12 nm or 18 nm. The glass transition temperature Tg of the single thin films of P2CS is found to decrease with decreasing film thickness in a similar way as observed for polystyrene thin films. The magnitude of the depression of Tg for the stacked thin films is larger than that of the single thin films with corresponding thickness. The depression of the temperature at which the dielectric loss shows a peak due to the α-process at a given frequency, Tα, is larger than that of the single thin films, although the magnitude is smaller than that of Tg. Annealing at a high temperature could cause the Tg and Tα of the stacked thin films to approach the values of the bulk system.