Alcogel formation analysis: An important step for scCO2 aerogel production

The production of biopolymeric aerogels, for tissue engineering, currently involves three steps: gelation (hydrogel), solvent exchange (alcogel), and supercritical drying (aerogel). The alcogel formation, the longest step, can be optimised by exploring high pressures/mild temperatures. This work aimed to integrate/optimise the production process of alginate/gelatine aerogels, by performing solvent exchange and drying continuously within the same equipment. High-pressure solvent exchange (HPSE) was compared with the conventional method by analysing the alcogel and solvent with two complementary analytical techniques: Differential Scanning Calorimetry (DSC) and Refractive Index (RI). HPSE resulted in a faster solvent exchange, reducing 86 % of the processing time. The solvent exchange conditions did not significantly affect the aerogel structure, density, porosity, and surface area. Still, HPSE and the drying time influenced pore distribution and decreased mechanical properties. The drying stage was optimised to 2 h, showing the feasibility of integrating solvent exchange and supercritical drying for alginate-gelatine aerogels production.