Substrate Effect on T_g of Random Copolymers of 4-tert-butylstyrene and 4-acetoxystyrene

Confinement effect on the dynamics of polymers in nanoscale films is known to cause variations in the glass transition temperature, T_g, of the films with film thickness. We studied the T_g of random copolymers of 4-tert-butylstyrene (4TBS) and 4-acetoxystyrene (4AS). Our result indicates that the component with a stronger substrate confinement effect dominates the T_g of the copolymer films. We have also explored the influence of pre-annealing time on the T_g’s. According to a previous study, by shortening the pre-annealing time, the T_g reductions of thin 4TBS films were enhanced. In our copolymer films, we found that that adjusting the pre-annealing time only affected the T_g of the copolymer films in which 4TBS is the majority component.