Laws of the Formation and Diffusion Properties of Silica and Agarose Gels

Abstract

The physicochemical and mass-transfer properties were studied for two gels that can be applied in the fabrication of bioreactors using additive manufacturing. The fundamental difference between these gels lies in the mechanisms of their formation from solutions. The first one is a silicic acid gel, which is formed in a chemical reaction and has an irreversible gelling process. The second one is an agarose gel, which is formed from a water solution of agarose upon cooling and turns back into liquid when heated. Studies were performed by optical methods that include the spectroscopy of gel samples during their formation and the visualization of the diffusion fronts of transferred substances. Being nonintrusive, these methods have no effect on the state of samples and do not distort the dynamics of processes. Characteristic patterns of changes in the spectral parameters during gelling were studied for both gels depending on the dispersed phase concentration, which was relevant to the practical application of the gels. New experimental data were obtained on the structure of the gels and the mechanisms of its change during gel aging. The main laws are determined for changes in the diffusion coefficients in the gels with increasing concentration of the dispersed phase.