ADSORPTION FRACTIONATION STUDIES BY SIZE-RESOLVED PULSED-GRADIENT SPIN-ECHO - NMR

In this paper the ability of pulsed-gradient spin-echo nuclear magnetic resonance (PGSE-NMR) to study adsorption fractionation is demonstrated. An inverse Laplace transform applied to the attenuation function yields a representation of the distribution of self-diffusion coefficients. The self-diffusion coefficient distributions of two model systems consisting of bimodal poly(ethylene oxide) (PEG) solutions have been examined in the absence and in the presence of silica particles. The results show that high molecular weight species are preferentially adsorbed over smaller ones as predicted by theory confirming the feasibility of the PGSE-NMR technique to study such distributions.