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

Abstract

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 1H 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 2 −1) with respect to τ −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.