The Phase Behavior and Thermal Stability of Blends of Poly(styrene-co-methacrylic acid)/Poly(styrene-co-4-vinylpyridine)

The hydrogen bonding and miscibility behaviors of poly(styrene-co-methacrylic acid) (PSMA20) containing 20% of methacrylic acid with copolymers of poly(styrene-co-4-vinylpyridine) (PS4VP) containing 5, 15, 30, 40, and 50%, respectively, of 4-vinylpyridine were investigated by differential scanning calorimetry, thermo-gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). It was shown that all the blends have a single glass transition over the entire composition range. The obtained T(g)s of PSMA20/PS4VP blends containing an excess amount of PS4VP, above 15% of 4VP in the copolymer, were found to be significantly higher than those observed for each individual component of the mixture, indicating that these blends are able to form interpolymer complexes. The FTIR study reveals presence of intermolecular hydrogen-bonding interaction between vinylpyridine nitrogen atom and the hydroxyl of MMA group and intensifies when the amount of 4VP is increased in PS4VP copolymers. A new band characterizing these interactions at 1724 cm(-1) was observed. In addition, the quantitative FTIR study carried out for PSMA20/PS4VP blends was also performed for the methacrylic acid and 4-vinylpyridine functional groups. The TGA study confirmed that the thermal stability of these blends was clearly improved. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 462-468, 2011