Cross-polarization with magic-angle spinning kinetics and impedance spectroscopy study of proton mobility, local disorder, and thermal equilibration inhydrogen-bondedpoly(methacrylic acid)

The(1)H-C-13 cross-polarization with magic-angle spinning (CP MAS) kinetics was studied in poly(methacrylic acid) (PMAA) having the purpose to track the links between the local order in the main chain and the proton dynamics in peripheral hydrogen bond networks. The experimental CP MAS kinetic curves were analyzed applying the models of isotropic and anisotropic spin-diffusion with thermal equilibration. The fractal dimensionD(p)approximate to 3 was deduced that indicates that PMAA behaves as an isotropic 3D-system. No proton conductivity in the neat PMAA was deduced from the impedance spectroscopy data analyzing the frequency dependences of the complex dielectric permittivity. The value of local order parameterS= 0.70 for CH(2)in PMAA occupies an intermediate position between 0.63 and 0.85 deduced for CH(2)sites in the main chains of poly(vinyl phosphonic acid) and poly(2-hydroxyethyl methacrylate), that is, the true proton conductor and the polymer that contains the H-bond network, however, no proton conductivity, respectively.