Temperature dependence of refractive index of films of well-defined linear and star-shaped polystyrenes

Well-defined linear and star-shaped polystyrenes were synthesized, and the temperature dependence of their refractive index (n(D)) in the film state was examined. The values of n(D) decreased with increasing temperature, with an inflection at the glass-transition temperature (T-g). Above the T-g, the values of difference of n(D) between star-shaped polymer and linear polymer increased at elevated temperatures.