Miscibility in Blends of Poly(N-vinylpyrrolidone) and Poly(styrene-co-methacrylic acid).

The miscibility and interactions in blends of poly(N-vinylpyrrolidone) (PVP) and poly(styrene-co-methacrylic acid) (P(S-co-MAA)) with several MAA contents were investigated by DSC analyses and Fourier transform infrared (FT-IR) spectroscopy. It was found that PVP/P(S-co-MAA) blends were immiscible in most of blend compositions when MAA content of P(S-co-MAA) is smaller than 4.8 mol%. However, the miscible region of the PVP/(S-co-MAA) blends become wider with increasing MAA content in P(S-co-MAA). In addition, the PVP/ P(S-co-MAA) blends are miscible when MAA content of P(S-co-MAA) is larger than 12 mol%. It was suggested by FT-IR analyses that the miscibility of the PVP/P(S-co-MAA) blends were derived by associative interaction between carbonyl groups of PVP and MAA units of P(S-co-MAA).