Cellulose aerogels are interesting platforms for biomedical and drug delivery applications, due to their biocompatibility, biodegradability, water absorption capacity, and good textural properties. Supercritical CO2 drying has been proven as an efficient technology for obtaining aerogels and preserving the porous structure. In this work, the effect of relevant process variables (CO2 density, depressurization rate, and intermediate depressurization mode) and gel composition on the textural properties of cellulose aerogels is studied. Experiments are performed in batch-mode, and aerogel monoliths are characterized in terms of apparent density, porosity, specific surface area, and crystalline morphology. Water uptake in different buffer solutions is also evaluated. The use of thiourea in the gel formation leads to lower porosity. On the other hand, higher porosity and surface area are obtained when depressurization is slow and the system is only partially depressurized between drying cycles. Aerogels showed a good and fast water uptake capacity, regardless of the pH (200–500 %).

中文翻译：

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超临界 CO2 干燥变量和凝胶组成对纤维素气凝胶质构特性的影响


纤维素气凝胶因其生物相容性、生物降解性、吸水能力和良好的质构特性而成为生物医学和药物递送应用的有趣平台。超临界 CO2 干燥已被证明是获得气凝胶和保持多孔结构的有效技术。在这项工作中，研究了相关过程变量 （CO2 密度、减压速率和中间减压模式） 和凝胶组成对纤维素气凝胶结构特性的影响。实验以批处理模式进行，气凝胶整体根据表观密度、孔隙率、比表面积和晶体形态进行表征。还评估了不同缓冲溶液中的吸水率。在凝胶形成中使用硫脲可降低孔隙率。另一方面，当减压缓慢且系统在干燥循环之间仅部分减压时，可获得更高的孔隙率和表面积。气凝胶显示出良好且快速的吸水能力，无论 pH 值 （200–500 %）如何。