H-1 NMR imaging and spectroscopy studies of the polymerization of acrylamide gels

H-1 nuclear magnetic resonance spectra and images have been acquired during polymerization of a mixture of soluble reactive methacrylamide (monomer) and N,N'-methylenebisacrylamide (cross-linking molecule). The mixture was polymerized by adding ammonium persulfate (initiator) and tetramethylethylenediamine (accelerator) to form long-chain, cross-linked polymers. Study of the time-varying spin-lattice relaxation times (T-1) during the polymerization was conducted at 25 and 35 degrees C and the variation of spectra and T-1 with respect to the extent of polymerization was determined. To verify homogeneous polymerization, multidimensional H-1 NMR imaging was utilized for in-situ monitoring of the process. The intensities from the images are modeled and the correspondence shows a direct extraction of T-1 data from the images.