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

该项目的总体目标是建立孔隙结构，溶质-壁相互作用和限制在多孔载体中的大型有机分子的非晶相变之间的功能。这一知识将使有机物质在定制载体中的无定形状态的特定稳定化成为可能，这在制药技术和其他应用中具有特别重要的意义。这一目标应该通过实验研究和元胞自动机建模来实现。在项目的前两年，建立了超临界色谱法表征溶质-载体相互作用，并对两种不同的溶质（苯甲酸、萘）和几种具有不同形态和表面功能化的气凝胶样品进行了表征。进一步发现，不仅溶质和载体的性质（如预期的那样），而且溶剂的性质（超临界CO2的密度）也决定了溶质在气凝胶孔隙中的结晶度。应用基于元胞自动机的多孔气凝胶扩散模型，并将其扩展到气凝胶结构的三维描述。在二期工程中，应进一步研究溶剂性质对结晶度的影响。由于结晶本身已经被研究过，主要的注意力将集中在再结晶过程和在孔隙中获得的非晶相的稳定性上。三维元胞自动机模型不仅可以描述吸附本身，还可以描述整个色谱实验，以便与实验数据进行直接比较。

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.