Carbon-13 nuclear magnetic resonance study on poly(ethylacrylate-co-sodium acrylate) ionomer

The poly(ethylacrylate) (PEA) homopolymer and poly(ethylacrylate-co-sodium acrylate) ionomer that contain 8.4 mol % ionic groups (PEANa-8.4) were studied by C-13 using cross polarization and magic angle spinning nuclear magnetic resonance (CP/MAS NMR). The C-13 spin-lattice relaxation times in a rotating frame, T-1rho, were measured as functions of the temperature. Using these T-1rho spin-lattice relaxation times, we addressed the chain mobility, correlation time, and activation energy for carbon of the PEA homopolymer and the PEANa-8.4 ionomer. We found that the molecular motion in the PEA homopolymer needed a higher activation energy than that in the PEANa-8.4 ionomer. In addition, we observed that motion of the 1-methyl carbons in the PEANa-8.4 ionomer was distinctly different from that in the PEA homopolymer: the value of T-1rho for 1-methyl carbon is ascribed to stronger interactions between the polymer chains in the homopolymer. (C) 2003 American Institute of Physics.