NMR studies of conformation and molecular motion of poly(methyl methacrylate) in solution

Abstract

AbstractNMR shift reagent, tris(dipivalomethanato)europium(III), was applied to the 1H NMR measurement of isotactic and syndiotactic poly(methyl methacrylate) in solution in the temperature range 25–80°C. The solvents used were benzene (C6D6), chloroform (CDCl3), and carbon tetrachloride (CCl4). By comparing the observed values of paramagnetically induced shift with the values of geometric factor calculated for several kinds of conformational models hitherto proposed for these polymers, the possible conformations of the respective polymers in solution were eludicated. Furthermore the variation, as a function of temperature, of the carbon‐13 spin‐lattice relaxation times of individual carbons of isotactic and syndiotactic poly(methyl methacrylate) in benzene and chloroform solutions were measured and the correlation between the molecular motion and the conformation is discussed. It is pointed out that the conformation depends both on the stereochemical configuration and the nature of solvent, and the molecular motion depends both on the conformation and the configuration.