Effect of Deuterium Substitution on the Physical Properties of Polymer Melts and Blends

Using our simple lattice-based equation of state, we capture the effect of deuterium substitution in polystyrene (PS), predicting both the pure component melt properties and the remarkable shift in the coexistence curve when hPS is replaced by dPS in forming a blend with poly(vinyl methyl ether) (PVME). Taking advantage of a rare opportunity to compare with experimental pure component data, we demonstrate that by characterizing the deuterated component through analysis of neutron scattering data, we are able tomake predictions for the pure dPSPVT properties which are in superb agreement with experiment. Calculations andmeasurement show that the dPS volume (per repeat unit) is slightly larger than that for hPS at low pressure, an effect which can be correlated with a difference in the model energetic parameter (ε). In addition, we find that the dPS coefficient of thermal expansion (R) is larger than that for hPS and thus closer to the value for PVME.We propose that the increased similarity of theR’s for dPS and PVME is connected to the increased miscibility of the dPS/PVME blend, a linkage which may be helpful to experimentalists in anticipating the potential effect on phase stability of polymer blends when deuterium substitution is employed.