THE ISSUE OF MORPHOLOGY AND MOLECULAR ACCESSIBILITY OF SWOLLEN GEL-TYPE RESINS - AN INTEGRATED INVERSE STERIC EXCLUSION CHROMATOGRAPHY ELECTRON-SPIN-RESONANCE NMR APPROACH

A number of microporous fairly hydrophilic oly(N,N-dimethylacrylamide- methylenebisacrylamide) (poly-(DMAA-MBAA)) resins (cross-linking degre e from 2 to 8%) have been examined with techniques that provide inform ation on the structure on the nanometer scale and molecular accessibil ity of these materials in the swollen state. Electron spin resonance ( ESR), pulsed-gradient-spin-echo nuclear magnetic resonance (PGSE-NMR) spectroscopies, and inverse steric exclusion chromatography (ISEC) gav e consistent results in water, tetrahydrofuran (THF), and dichlorometh ane (DCM). The results are interpreted on the basis of physical models which fit reasonably the experimental data. The resulting equations b etween the translational diffusion coefficient of the solvent, the rot ational correlation time of the spin-probe 2,2,6,6-tetramethyl-4-oxo-1 -oxylpyperidine (TEMPONE) dispersed inside the swollen resins, and the polymer chain concentration appear to be promising tools in the desig n of macromolecular materials for chemical and catalytic applications.