Carbon-13 nuclear magnetic resonance spectra of water-soluble polymers

13C-NMR spectroscopy was applied to the analysis of various water-soluble polymers used industrially from the analytical point of view. 13C-NMR spectra were measured in D2O solutions using a JEOL JNM-FX90Q FT-NMR spectrometer at 22.53 MHz with complete proton decoupling and gated (non-NOE) decoupling techniques. 13C-NMR spectra were examined in detail and were found to give important information about polymer structures shown as follows: (1) identification of monomers in a collagen peptide, poly (acrylic acid), and poly (acrylic acid-maleic acid), (2) structural analysis of amine-epichlorohydrin copolymer which is synthesized in water and its structure is changed by removing water, (3) discrimination between block and random copolymers of ethylene oxide-propylene oxide; the variation of the monomer sequence distributions is related closely to that of properties such as surface activity, (4) analysis of stereoregularity in poly (vinyl alcohol-vinyl acetate) and poly (N-vinyl-2-pyrrolidone). These are all difficult problems to solve by infrared and 1H-NMR methods. Thus, 13C-NMR spectroscopy was indicated to be useful for the characterization of polymer structures.