Miscibility of tetramethyl‐hexafluoro copolycarbonates with styrene‐methyl methacrylate copolymers

The compositions for which blends of copolycarbonates of tetramethyl bisphenol‐A and hexafluoro bisphenol‐A (TMPC‐HFPC) with styrene‐methyl methacrylate copolymers (SMMA) are miscible were determined experimentally. These copolymer compsition boundaries were compared to predictions based on the Flory‐Huggins theory combined with the binary interaction model. The theoretical predictions employed interaction energies from the literature for the TMPC/PS, PS/PMMA, and TMPC/PMMA pairs, and values for the TMPC/HFPC, HFPC/PS, and HFPC/PMMA pairs were established or verified using independent experiments. The recommended set of interaction energies predicts that miscibility occurs in two separate regions of copolymer compositions. These predictions agree well with the experimental observations. The theoretical requirements for a single, continuous miscible region versus two disjointed miscible regions when the two limiting homopolymer pairs exhibit miscibility, that is, TMPC‐PS and HFPC‐PMMA in this example, are described.