PROTON SPIN-DIFFUSION FOR SPATIAL HETEROGENEITY AND MORPHOLOGY INVESTIGATIONS OF POLYMERS

The diffusion of Zeeman spin order in the laboratory frame for a syste m with microscopic spatial heterogeneity, due to either molecular mobi lity or chemical heterogeneity, has been analysed by solving the diffu sion equation in the limit of two different models. By simulation of p roton spin diffusion nuclear magnetic resonance (NMR) spectral areas f or poly(ethylene oxide) we have demonstrated, for both models, the sen sitivity of these observables to phase domain size and to the dimensio nality of the diffusion process. The possibility to obtain information about the morphology is analysed. Results from calculations based on the two models are compared with experimental spin diffusion results f rom H-1 NMR spectra of poly(ethylene oxide). Two methods for filtering the z-magnetization from the different phase domains in a solid are d iscussed. The efficiency of a magnetization dipolar filter based on ma gic and polarization echoes is presented.