ENTHALPIES OF POLY(METHYL METHACRYLATE) M IXING WITH DONOR AND ACCEPTOR SOLVENTS

The concentration dependences of the mean and partial enthalpies of PM MA mixing with chloroform, DMF, ethyl acetate, acetone, acetonitrile, and toluene at 298 K were studied by calorimetry in the entire composi tion range. PMMA interacts more strongly with acceptor solvents than w ith donor solvents. The mean molar enthalpies of interaction at 298 K were calculated for all the systems examined, taking into account the glassy state of PMMA. It was shown that heat is evolved on interaction of PMMA with chloroform. In contrast, heat is absorbed on interaction of PMMA with DMF, acetone, acetonitrile, and toluene. The results are explained by possible hydrogen bonding in solutions or by formation o f stereocomplexes and associates between the PMMA chains and the solve nt molecules.