Diffusivity of alcohols in amorphous polystyrene

Gravimetry is used to study the diffusion of a homologous series of alcohols (C n , with n = 1, 2, 3, 4, 6, 10, and 16) in amorphous polystyrene at temperatures from 35 to 145°C, that is both below and above the polymer glass transition temperature of 100°C. All the mass uptake results are well described by a simple Fickian model (for t < t 1/2 ) and are used to calculate the corresponding diffusion coefficients using the thin‐film approximation. At any particular temperature, the alcohols C n with n = 3, 4, and 6 possess very similar diffusivities despite the fact that the chain length doubles from C 3 to C 6 . This peculiar diffusivity behavior is explained based on the variation of the polymer–solvent chemical affinity along the homologous series. As expected, at any particular temperature, the diffusivity decreases considerably from C 6 to C 10 and from C 10 to C 16 . For each alcohol, its log( D ) increases linearly with the decrease in liquid viscosity associated with an increase in temperature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013