MOLECULAR-MOTION AND H-1-NMR RELAXATION OF AQUEOUS POLY(N-ISOPROPYLACRYLAMIDE) SOLUTION UNDER HIGH-PRESSURE

In order to obtain useful information about the molecular motion and structure of poly (N-isopropylacrylamide) (PNiPAM) in aqueous solution, proton spin-lattice relaxation times, proton spin-spin relaxation times, and volume changes were measured at pressures from 1 to 400 kg/cm2 as a function of temperature. We found that the molecular motion and the structure of water and PNiPAM in PNiPAM/water solution transitionally change at gelation temperature (31-degrees-C). The effect of pressure on such transitional changes is studied. It is suggested that application of pressure to the system prevents the gelation.