| Abstract: | The temperature and concentration dependences of the physical state of solutions of an acrylonitrile-sodium methallylsulfonate copolymer in dimethyl sulfoxide (DMSO) are investigated from calorimetric and NMR measurements within the temperature range where the solvent crystallization and/or polymer ordering in solution can occur. (i) For solutions of global monomeric molar fraction higher than 0.45, ordering of a fraction (<0.15) of the polymer can occur. Temperatures of polymer melting and polymer ordering are reported. The composition of the liquid phase coexisting with ordered polymer is found to depend on the global concentration of the solution. At low temperatures, i.e., at temperatures for which DMSO crystallizes, three phases are found to coexist: ordered polymer, crystalline DMSO and disordered solution. (ii) For solutions of global monomeric molar fractions smaller than 0.45, the polymer is disordered at all temperatures. Crystallization of pure DMSO is observed and the melting/crystallization curve of DMSO is determined by NMR and described with simple thermodynamic considerations. |
