H-1-NMR STUDY OF HINDERED INTERNAL-ROTATION AND HYDROGEN-EXCHANGE OF AMIDE SIDE-CHAIN OF POLY(ACRYLAMIDE) IN AQUEOUS-SOLUTION

Structure and dynamics properties of poly(acrylamide)(PAAm) side-chain s are investigated by H-1 NMR methods. The multiplicity of H-1 spectra of NH2 protons of PAAm side-chains is attributed to the tacticity spl itting at the triad level. The proton exchange and the hindered intern al rotation of the NH2 group are studied by examining pH and temperatu re dependences of the H-1 spectra. It is found that the proton exchang e rates of the two NH2 protons with solvent water are almost the same. The activation energy of hindered internal rotation is found to be ab out 58 +/- 9 kJ mol-1. The present results indicate that there is no h ydrogen bonding between amide groups of neighboring units.