The Local Structure around Sodium Ions in Poly(ethylene-ran-methacrylic acid) Ionomers Studied by23Na Solid-state NMR under a High Magnetic Field, 21.9 T

Abstract The local structure of sodium ions in poly(ethylene-ran-methacrylic acid) ionomer neutralized by sodium hydroxide has been investigated using 23Na MAS and multiple-quantum-magic-angle-spinning (MQMAS) NMR techniques at a high magnetic field. Isotropic chemical shifts and quadrupolar coupling products of three kinds of nonequivalent 23Na ions, i.e., isolated, hydrated, and aggregated 23Na ions were estimated from peak positions in 23Na MQMAS spectra. The MQMAS technique at high magnetic fields is expected to be a powerful tool to investigate the local structure in amorphous systems containing quadrupole nuclei.