The structural parameters of rigid matrix of saccharide-based gel described by short and long diffusion regime analysis

Abstract

The tortuosity–porosity relation and internal structure diameters in a selected organogel are studied. The diffusion coefficient measured by pulsed field gradient NMR at short and long observation times can be used to estimate the tortuosity and the pore surface-to-volume (S/Vpore) ratio of a porous material (Latour et al. in J Magn Res A 112:83–91, 1995; Mair et al. in Magn Res Imaging 19:345–351, 2001; Mitra et al. in Phys Rev B 47(14):8565–8574, 1993; Valiullin and Skirda in J Chem Phys 114:452–458, 2001). The value of S/Vpore allows to calculate the average pore and barrier diameters. In the experiment, the time-dependent diffusion coefficient of toluene in a low molecular weight gelator methyl-4,6-O-(p-nitrobenzylidene)-α-d-glucopyranoside (Gluco-NO2) matrix was measured. The results revealed the relation between the diffusion coefficient of toluene and the concentration of gelator Gluco-NO2 in the system. With increasing Gluco-NO2 compound in the sample, the diffusion coefficient of toluene decreases. On the basis of the diffusion coefficient behaviour as a function of time and gelator concentration, the fibrous structure of the gel matrix was identified and the structural parameters of the system were investigated.