Impregnation of Materials in Supercritical CO₂ to Impart Various Functionalities

Abstract

Supercritical CO 2 (scCO 2) impregnation has attracted growing interest due to its unique properties such as high diffusivity, low surface tension, and ease of solvent removal at the end of the process. In addition, scCO 2 is the most environmentally acceptable solvent possessing many advantages compared with the conventional aqueous and solvent-based processing. scCO 2 impregnation has a wide range of applications mainly used to incorporate various active principles such as pharmaceuticals, functional finishing agents, colorants, and other agents into a polymeric matrix. This chapter reviews some studies carried out so far about the application of scCO 2 as impregnation medium to develop various functional materials and it is intended to stimulate further research into the application of scCO 2 to textile functionalization. It mainly focuses on applications related to textiles and some polymeric films.

Supply Chains for Hydrogen and Carbon Dioxide for Sustainable Production of Base Chemicals

“…Its supercritical point at 31.1°C and 73.8 bar allows CO 2 to become supercritical under mild conditions [174]. Supercritical CO 2 is widely used across industries, acting as a reaction medium for catalysis [202], extractant in coffee decaffeination [203], and aiding the textile industry in dyeing and impregnating [204] fibers and polymers [205]. Its role also extends to other industrial processes, including dispersion polymerization [206,207], fractionation, and powder polymer formation [208,209].…”

Active Flexible Films for Food Packaging: A Review

“…The supercritical impregnation process is a recent technique used to impregnate active agents in packaging materials. The supercritical fluids (SCFs) have been used as solvent, anti-solvent or plasticizer, in different applications, such as extraction, dyeing, cleaning, fractionation, polymerization, polymer processing, encapsulation, among others [73,74]. Supercritical solvent impregnation has been recently used to develop active packaging, as an alternative to conventional techniques.…”

“…Moreover, the supercritical fluid can work as a carrier of the active agent and change the matrix properties (e.g., swell), thus ensuring the impregnation success. Carbon dioxide (CO 2 ) is one of the most used SCFs, since it offers several advantages, such as low toxicity, low cost, non-flammability, environmental sustainability, and it is chemically inert under many conditions [74,75].…”

“…Finally, the CO 2 molecules are removed by the shrinking polymer (depressurization step), and the impregnated molecules are trapped inside the polymer matrix. The impregnation process depends on the pressure, temperature, depressurization rate and time, variables that should be optimized [74,75].…”

“…However, despite the wide applicability and advantages, the production processes have found little space in the food industry, mainly in food packaging area, due to its high production cost. While the pharmaceutical and cosmetic sectors often support the use of high-cost methodologies, the food industry works with lower profit margins, and therefore, production costs should be maintained low [74]. As a consequence, the use of carriers loaded with active compounds and their incorporation in food packaging has not been widely studied.…”