Adsorptive precipitation of polar organic substances in biopolymer aerogels from ternary supercritical fluid mixtures

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The overall goal of the project is to establish the functionality between the pore structure, solute-wall interactions and amorph-crystalline phase transitions of large organic molecules confined in porous carriers. This knowledge would enable the specific stabilization of the amorphous state of organic substances in the tailor-made carriers, which is of special importance in pharmaceutical technology and other applications. This goal should be achieved by means of both the experimental investigation and modelling by cellular automata.In the first 2 years of the project the characterization of the solute-carrier interactions by supercritical chromatography was established and carried out for 2 different solutes (benzoic acid, naphthalene) and several aerogel samples with different morphology and surface functionalization. Further it was found that not only the properties of the solute and the carrier (as expected), but also the properties of the solvent (density of supercritical CO2) determine the crystallinity of the solute in the pores of the aerogels. Cellular automata-based modelling of diffusion in porous aerogels was applied and extended to 3D description of the aerogel structure. In the second project period the effect of the solvent properties on the crystallinity should be further investigated. Since the crystallization itself is already studied, main attention would be focused on the recrystallisation process and the stability of the gained amorphous phase in the pores. The modelling with cellular automata in 3D mode should be extended to describe not only the adsorption itself but also the whole chromatographic experiment to be directly compared with the experimental data.