Polymer-solvent interactions in thermoreversible gels of isotactic poly(methyl methacrylate) as studied by measurement of H-1 NMR relaxation of the solvent

Dynamic structure and polymer-solvent interactions in solutions and gels of isotactic (i) poly(methyl methacrylate) (PMMA) in butyl acetate (BAC) were characterized by measurements of nonselective and selective H-1 NMR spin-l attice relaxation times of the solvent. In thermoreversible gels, the exist ence of i-PMMA-BAC complex, where the life-time of the bound solvent is sim ilar to 100 ms or shorter, was confirmed. Although the correlation time of the solvent bound in i-PMMA-BAC complex is 5-10 times longer than for the f ree solvent, there is still a relative motional freedom for complexed solve nt molecules. The same behaviour observed recently for thermoreversible gel s of syndiotactic PMMA indicates the same character of polymer-solvent comp lexes in gels of both stereoregular forms of PMMA.