Effects of supercritical carbon dioxide processing on the properties of chitosan–alginate membranes

• Chitosan–alginate membranes were processed with supercritical CO2 (scCO2).
• scCO2 processing increased porosity and water vapor permeability of the membranes.
• scCO2 processing may be used to control the characteristics of the membranes.

Chitosan–alginate membranes with different porosities designed to be used as wound dressings or scaffolds were processed in supercritical CO2 (scCO2) with the aim of improving their physicochemical properties. The membranes were characterized before and after processing at 100 or 300 bar and 45 °C for 2 h with a depressurization rate of 5 bar/min. The results show that after processing, thickness, real density and porosity increased up to 68%, 100% and 167%, respectively, and surface area decreased up to 47%. Because of changes in structure, water vapor sorption and permeability increased up to 53% and 84%, respectively. Stabilization of the chitosan–alginate complex was noticed after processing with scCO2 according to thermal analysis. The results indicate that supercritical CO2 processing made the membranes more adequate for use as wound dressings.

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