STUDY OF THE PRODUCTION PARAMETERS INFLUENCE OF HIGHLY POROUS CELLULOSIC MATERIALS ON THEIR STRUCTURAL CHARACTERISTICS

Abstract

Highly porous materials based on natural polymers are present of particular interest in various applications. Among them, for example, biomedicine, water purification, thermal insulation. This paper describes the developed method for obtaining highly porous materials based on cellulose, which include: dissolving microcrystalline cellulose in an aqueous solution of sodium hydroxide with urea; cross-linking cellulose using epichlorohydrin; drying the resulting gels. The influence of the concentrations of cellulose and the crosslinking agent and the drying method – freeze-drying (obtaining cryogels) and supercritical drying (obtaining aerogels) – on the final structural characteristics of the obtained materials has been studied. Cryogels and aerogels based on cellulose have been characterized by helium pycnometry, nitrogen porosimetry, and scanning electron microscopy. It was found that with an increase in the concentration of cellulose and epichlorohydrin, the porosity of the samples significantly decreases (from 84% to 22% for aerogels). For samples with the highest concentration of the crosslinking agent, the porosity of cryogels is higher (63%) than that of aerogels (22%). The specific surface area and mesopore volume were determined by nitrogen porosimetry, and nitrogen adsorption-desorption isotherms were obtained. Despite the fact that aerogels have a lower porosity, they are characterized by a higher specific surface area than cryogels (162 m2/g for aerogel and 65 m2/g for cryogel containing 6 wt.% cellulose and 4 wt.% epichlorohydrin). Scanning electron microscopy images were obtained, from which it can be seen that aerogels have a porous fibrous structure, while cryogels are characterized by a layered macroporous structure. The use of supercritical drying using CO2 avoids the destruction of the mesoporous structure of the material. For citation: Fedotova O.V., Trofimova K.V., Tsygankov P.Y., Safarov R.R. Study of the production parameters influence of highly porous cellulosic materials on their structural characteristics. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 107-113. DOI: 10.6060/ivkkt.20236602.6736.