Nanopore confinement and fluid behavior in nanocellulose–based hydro- and organogels

The morphology of nanofibrillated cellulose (cellulose nanofibrils or CNF) systems were probed with inorganic water and organic ester as the tracers to determine the porous structure of CNF skeleton. The main novelty of the work was the determined dramatical changes in the gel microscaled porous morphology under replacement of inorganic water by organic ester in the CNF samples of the same origin. For this aim a well-known and well-tested pulsed-field-gradient (PFG) NMR strategy for analyzing mesh size in different porous media was used. For the data analysis the phenomenological scaling approach was applied. It was shown, that the average size of free porous medium dramatically decreases during the transfer of celllose nanofibrils from the inorganic water phase (43 μm) to the organic ester one (1–2 μm). Cooperative analysis of NMR and SEM data for the water and ester CNF-based gels has shown the essential difference in nanoscaled organization of cellulose supramolecular structure. The replacement of water by ester provides the transfer of nanofibrilles to more dispersed state at the nanoscale, which is also confirmed by FTIR experiments