Blends of poly(isobutyl methacrylate-co-acrylic acid) with poly{styrene-co-[2-(N,N-dimethyl amino)ethyl methacrylate]} or poly(styrene-co-4-vinylpyridine

The miscibility of poly(isobutyl methacrylate-co-acrylic acid) (IBMAA) with poly{styrene-co-[2-(N,N-dimethyl amino) ethyl methacrylate]} (SDAEM) or poly(styrene-co-4-vinylpyridine) (S4VP) was studied by differential scanning calorimetry and inverse gas chromatography. IBMAA containing 10 mol% of acrylic acid was found to be immiscible in all proportions with not only SDAEM containing 6 mol% of [2-(N,N-dimethyl amino) ethyl methacrylate] but also with (S4VP) containing 15 or 22 mol% of 4-vinylpyridine. However, as a result of a higher level of specific favorable interactions between moieties in the copolymers, the same isobutyl methacrylate copolymer (IBMAA-10) or copolymer of higher content of acrylic acid are miscible with SDAEM copolymer containing 12 mol% of the basic comonomer, as evidenced from the single glass transition temperature-composition determined by both techniques and the negative values of the apparent polymer-polymer interaction parameters. An attempt at interpretation of the miscibility of IBMAA-10/SDAEM-12 blends was carried out from the interaction energy densities and the solubility parameters of these copolymers and of their blends. Miscible blends of IBMAA-22 and S4VP-15 were also observed. (C) 1997 Elsevier Science Ltd.