Measurements of local magnetic field gradient and diffusion in polymers in the solid state

This paper describes two topics concerned with anisotropic molecular diffusion in a single crystal of stearic acid (SA) and measurements of local magnetic field gradient (MFG) in a powdered film of regio-regulated poly(4-methylthiazole-2,5-diyl)(HH-P4MeTz) by H-1 transverse relaxation time measurements with two pulse Hahn-echo (TPHE) and Carr-Purcell Meiboom-Gill (CPMG) nuclear magnetic resonance (NMR) spectroscopy. The plots of the relaxation rate (T 1) with respect to tau(-1), were fitted by a numerical Green function solution of Torrey's diffusion equation, with a parabolic magnetic field gradient and thereby, the internal MFGs were estimated for SA and HH-P4MeTz. The local MFGs obtained are thought to be characteristic of each system, and would be closely related to the molecular and electronic structure. (C) 2002 Elsevier Science B.V. All rights reserved.