LIGHT-SCATTERING-STUDIES ON HYDROGEN-BONDED POLYMER BLENDS

Phase diagrams for poly(n-hexyl methacryrate) blends with a series of styrene-co-vinylphenol polymers have been mapped using light-scatterin g techniques. These are compared to theoretical phase diagrams calcula ted using an association model that incorporates the various interacti ons in hydrogen-bonded polymer systems. The thermodynamics of these bl ends is strongly affected by the competition between the self-associat ing and interassociating hydrogen bonds and the unfavorable dispersive interactions. The balance of these competing factors controls the tem perature and composition of phase separation. The results of the theor etical predictions are found to be in good accord with the experimenta l phase diagrams. They also help in explaining the molecular weight in dependence and the skewness (asymmetry) of the phase diagrams.