Interactions in blends of bisphenol-A polycarbonate and poly(styrene-co-methacrylic acid)

Interactions in bisphenol-A polycarbonate/poly(styrene-co-methacrylic acid) (PC/P(S-MAA)) blends, which show UCST phase transition and Miscibility Valley phenomena in temperature-copolymer composition plane, were investigated by Fourier transform infrared (FT-IR) spectroscopy. It was found that methacrylic acid (MAA) units in poly(styrene-co-methacrylic acid) (P(S-MAA)) formed associated dimers at low temperature and the dimer dissociated with elevating temperature. Since the temperature dissociating associated dimer of MAA units was corresponding to phase transition temperature in PC/P(S-MAA) blends, the UCST phase behavior would be caused by association–dissociation in MAA units.