Study of Self-Diffusion of Molecules in Polymer Gel by Pulsed-Gradient Spin-Echo 1H NMR. 3. Stearyl Ιtaconamide/N,N-Dimethylacrylamide Copolymer Gels

Intermolecular hydrophobic interactions between poly(ethylene glycol) oleyl ether (PEG-Ole) as probe polymer and network polymer in stearyl itaconamide (SIA)/ N, N -dimethylacrylamide (DMAA) copolymer gel swollen with water, in which the micelle of SIA is immobilized by copolymerization, have been studied through the diffusion coefficient ( D ) determined by the pulsed-gradient spin-echo 1 H NMR method with the field gradient strength of 22.3 T m -1 and 1 H spin−lattice relaxation time ( T 1 ) and 1 H spin−spin relaxation time ( T 2 ) by the 1 H pulse NMR method. From these experimental results, it was found that in the diffusion process PEG-Ole in SIA/DMAA copolymer gel takes the mobile and immobile states, and 1 H T 2 of PEG-Ole in SIA/DMAA copolymer gel is shorter than that of PEG. This shows that the comicellization of PEG-Ole and SIA is induced by hydrophobic interaction between the oleyl group in PEG-Ole and the stearyl group in SIA. Furthermore, to elucidate kinetics of the incorporation of PEG-Ole into the micelle and the release of PEG-Ole from the micelle, the mean residence lifetimes of the aggregated and unaggregated states have been determined on the basis of the experimental results obtained as a function of the intervals of gradient pulses.