Spin diffusion and spin-lattice relaxation in multiphase polymers

A model which treats spin diffusion and spin-lattice relaxation in multiphase polymers on the same footing is proposed, This new approach allows for more accurate determination of domain sizes and interfacial thickness in the probed polymers. In a poly(styrene-b-isoprene) copolymer example a significant improvement in the agreement between the NMR measurements and the simulated results can be obtained with the incorporation of a spin-lattice relaxation term into the spin diffusion process. The obtained microphase structural parameters are similar to the small angle X-ray scattering results. In addition, the spin-lattice relaxation times (T-1) in different domains can be predicted reasonably well based on T(1)s of the component homopolymers and on the microphase structure in the present model. (C) 1997 American Institute of Physics.