Treatment of poly(styrene-co-methacrylic acid)/poly(4-vinylpyridine) blends in solution under liquid-liquid phase-separation conditions. A new method for phase-separation data attainment from viscosity measurements

Phase diagrams are contributed for polymer mixture systems in solution. One polymer has proton‐acceptor character and the other has growing proton‐donor nature, which is reflected in the phase diagrams. Usually, these diagrams are obtained from size‐exclusion chromatographic (SEC) measurements. A totally novel application, which is exposed in this report, is the construction of the phase diagram from the viscometric experiments of polymer mixtures. The evaluated binodal or cloud‐point isotherms so built agree well with those from SEC. The results indicate an augmentation in the dimensions of donor polymer B, in the presence of acceptor polymer C, intensifying with the concentration of C, which is interpreted as an B‐C association growing as the number of hydrogen bonds increases. An increment in the Huggins constant for BC, as the proportion of methacrylic acid in the donor copolymer increases, means an augmentation in the interaction for BC, indicating an extension of compatibility. Viscometric experiments evidence hydrogen bonds, intensifying as greater proportion of donor groups has polymer B, equal to that observed in the phase diagrams. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5039–5049, 2006