Chemical shift imaging NMR to track gel formation

In this work we have combined ¹H and ¹⁹F NMR chemical shift images to investigate the dynamic processes of gel formation of a cellulose solution. Chemical shift imaging (CSI) NMR is shown to be a valuable technique for studying phase changes in soft materials. The technique provides spatial position of each chemical component, and by repeatedly recording sample images the dynamic rearrangements in the material can be followed in detail. CSI NMR follows the same principles as magnetic resonance imaging, but can be performed on most of the nowadays commercial NMR probes. Position resolution of the chemical shift gives the opportunity to derive diffusion rate data of individual components during the gel formation process. The results suggest that the method can be used for detailed studies of dynamic processes in multi-component systems and to extract diffusion coefficients for the components investigated.