title: Diffusive diffraction phenomenon observed by PGSE NMR technique in a sugar-based low-molecular-mass gel.
abstract: The paper presents the diffusive diffraction phenomenon observed by the single-pulse-gradient spin-echo (s-PGSE) NMR technique in a real porous material: a gel composed of low-molecular-mass gelator methyl-4,6-O-(p-nitrobenzylidene)-α-D-glucopyranoside and toluene. Thanks to this phenomenon, we can probe the true microstructure (not xerogel) in which the toluene diffuses. To analyze the measured diffusion-diffraction pattern, we employed a composite bicompartmental model that superimposes restricted diffusion in small cavities of the gel matrix within the bundles of crossing fibers, with free diffusion in large and unconfined compartments between the bundles of crossing fibers. For restricted diffusion a pore-hopping formalism was applied. The observation of the diffraction pattern and its analysis leads to the conclusion that the pores, in the slow diffusing compartment of studied gel are ordered, at least locally, and relatively monodisperse with a size of 64 μm. Moreover, the restricting walls formed by the crossing fibers are perpendicular to the direction of the diffusion gradient.
authors.affiliation: Institute of Molecular Physics, Polish Academy of Sciences, Poznań, Poland. jtg@ifmpan.poznan.pl
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Tritt-Goc
authors.forename: Joanna
authors.initials: J
authors.lastname: Kowalczuk
mesh_terms: D002241:Carbohydrates / Q000737:chemistry*; D004058:Diffusion; D005782:Gels / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D008970:Molecular Weight; D009005:Monosaccharides / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry*
chemical_list: D002241:Carbohydrates; D005782:Gels; D009005:Monosaccharides; C578316:methyl-4,6-O-(p-nitrobenzylidene)-alpha-D-glucopyranoside; D014050:Toluene