SPATIAL INFORMATION ON A POLYMER GEL AS STUDIED BY H-1-NMR IMAGING .2. SHRINKAGE BY THE APPLICATION OF AN ELECTRIC-FIELD TO A POLYMER GEL

H-1 NMR imaging patterns with information about the spatial distribution of H-1 spin density and H-1 spin-spin relaxation time T-2 of water molecules in a cross-linked poly(methacrylic acid) (PMAA) gel were measured, in order to clarify the translational behavior of water molecules in the gel under shrinkage processes by the application of an electric field. From the experimental result it was found that a cylindrical gel shrank to a wine-stopper-like shape at long elapsed time after the application of an electric field. On the positive electrode side, the H-1 spin densities were high and the mobilities were low, and on the negative electrode side, the H-1 spin densities were low and the mobilities high. Further, details of the shrinkage process were discussed at the molecular level.