BLENDS OF POLY(ISOBUTYL METHACRYLATE) WITH POLY(STYRENE-CO-ACRYLIC ACID) AND OF POLY(ISOBUTYL METHACRYLATE-CO-ACRYLIC ACID) WITH POLY(STYRENE-CO-N,N-DIMETHYL AMINOETHYL METHACRYLATE)

The miscibility of poly(isobutyl methacrylate) with poly(styrene-co-ac rylic acid) and of poly(isobutyl methacrylate-co-acrylic acid) with po ly(styrene-co-N,N-dimethyl aminoethyl methacrylate) was studied by dif ferential scanning calorimetry and inverse gas chromatography. Poly(st yrene-co-acrylic acid), containing 20 or 32 mol% acrylic acid, and pol y(isobutyl methacrylate) were immiscible, as were blends of poly(isobu tyl methacrylate-co-acrylic acid) containing 10.5 mol% acrylic acid wi th poly(styrene-co-N,N-dimethyl aminoethyl methacrylate) containing 6 mol% of the basic comonomer. However, as a result of a higher level of favorable specific interactions between moieties in the two copolymer s, the same isobutyl methacrylate copolymer or copolymers with a great er content of acrylic acid are miscible with the styrene copolymer con taining 12 mol% N,N-dimethyl aminoethyl methacrylate, as suggested by the negative values of the apparent polymer-polymer interaction parame ters.