THERMODYNAMICS OF DISSOLUTION OF POLYACRY LIC-ACID IN DONOR AND ACCEPTOR SOLVENTS

Dissolution of PAA in various donor and acceptor solvents was studied at 273-423 K. A phase diagram with LCST was obtained for PAA-THF syste m. Mean specific enthalpy of mixing and partial excess enthalpy of the solvent were determined by calorimetry for the solutions of PAA in wa ter, the acceptor solvent (butanol), or the donor solvent (DMF), over the entire range of compositions and at different temperatures. Simila r data were also obtained for aqueous solutions of poly(methacrylic ac id) as the closest PAA homolog. PAA more readily interacts with the do nor compounds than with the acceptor ones. In contract to the other so lutions studied, the PAA-water system is characterized by abnormal ext rema in the concentration dependences of the partial excess enthalpy o f water, The results are discussed in terms of specific features of so lvation and association processes in PAA solutions.