SPIN-DIFFUSION AND SPIN-LATTICE RELAXATION IN MULTIPHASE POLYMERS

A model which treats spin diffusion and spin-lattice relaxation in mul tiphase polymers on the same footing is proposed, This new approach al lows for more accurate determination of domain sizes and interfacial t hickness in the probed polymers. In a poly(styrene-b-isoprene) copolym er example a significant improvement in the agreement between the NMR measurements and the simulated results can be obtained with the incorp oration of a spin-lattice relaxation term into the spin diffusion proc ess. The obtained microphase structural parameters are similar to the small angle X-ray scattering results. In addition, the spin-lattice re laxation times (T-1) in different domains can be predicted reasonably well based on T(1)s of the component homopolymers and on the microphas e structure in the present model. (C) 1997 American Institute of Physi cs.