Water Dynamics in Porous Biopolymer Networks: Data of Neutron Experiments

Abstract

The microscopic dynamics and macroscopic mass transfer of water molecules in porous networks of biopolymer gelatin gels was experimentally studied by quasi elastic neutron scattering (QENS) and neutron transmission technique, respectively. QENS data were processed within a novel approach taking into consideration the hierarchy of molecular motions in liquids. The “total” self — diffusion coefficient as well as it components corresponding to the collective (cluster like) and single — particle water molecule movements in gel pores of different sizes were extracted. Single — particle self — diffusion coefficients of free water obtained by QENS are consistent with macroscopic self — diffusion coefficients obtained by neutron transmission. Reduction of pore sizes leads to the gradual pumping of single — particle diffusive modes into collective ones. Purely collective diffusive modes and simultaneous almost complete retardation of macroscopic mass transfer of water are observed at relatively big values of pore sizes ≅25 Angstrom in consequence of confinement effect on liquid molecules mobility.