Processing of chitosan biopolymer into granules, films, and fibers

Abstract

Research of the last 10 years that was aimed at developing the theoretical bases for processing chitosan into granules, films, and fibers were reviewed. These items are interesting as sorbents, wound dressings, and separation membranes. Technically acceptable methods for preparing spherical granulated and fibrous, including nanofibrous, sorbents from chitosan and its composites with polyvinyl alcohol and potassium and copper hexacyanoferrate that exhibited high sorption capacity for heavy metals and radionuclides and were interesting for use in systems for reprocessing low-level liquid radioactive wastes and for performing ecological monitoring were developed.Research on chitin technology at the Department of Chemical Fiber and Nanomaterial Technology headed by L. S. Gal2braikh was carried out over 30 years. The results were published in over 200 articles, 10 patents, 15 candidate and 1 doctoral dissertation, and a monograph. The first 20 years of the research were mainly synthetic in nature and resulted in the development of improved methods for preparing chitosan; its sulfated derivatives, blood anticoagulants; carboxymethylated derivatives, polyampholytic complexants; polyelectrolyte complexes of chitosan, including effective hydrogel separation membranes; and surfactant-polyelectrolyte complexes with high surface and emulsifying activity. Herein we review briefly research results of the last 10 years, which were aimed at the development of the theoretical bases for processing chitosan into granules, films, and fibers, including nanofibers, which are interesting as sorbents, wound dressings, and separation membranes. These results were discussed in detail in the dissertations of M. A. Zotkin, E. V. Rumyantseva, S. A. Uspenskii, and A. N. Sonina.Chitosan is manufactured as amorphous crystalline powders. This makes it difficult to carry out sorption processes, especially under dynamic conditions. Processing of polymer solutions can produce sorbents of spherical or fibrous shape with high porosity and specific surface area, an amorphous structure, and increased sorption capacity. Such physical modification of the polymer can be combined with the preparation of chitosan composites with other sorbents (ferrite, kaolin, carbon), the specific properties of which expand the range of applications. Therefore, the development of sorbents based on chitosan with given functions and compositions, supramolecular and porous structure, physical shape, strength, and stability is a timely problem. Preparation and properties of acetic-acid solutions of chitosanChitosan is a high-melting amorphous crystalline polymer that is processed into items using solutions. The solvent for this is usually dilute acetic acid (AA), in which the polybase chitosan is converted into the water-soluble salt form. The swelling stage during dissolution of the polymer, which affects mainly its amorphous regions, is exothermic. Subsequent destruction of crystallites and dissolution are accelerated with heating. Formation of a gelatinous surface layer on...

Bioactive transparent films based on polysaccharides and cholinium carboxylate ionic liquids

“…[1][2][3][4] Polysaccharides, because of their abundance, diversity of structures and properties, represent one of the most explored families of biopolymers in this vast context. 1 In particular, polysaccharides such as chitosan and pullulan that can be easily processed into self-standing films and fibers are of particular relevance because of their applications in numerous fields, [5][6][7][8][9] and easy gathering of distinct functionalities or properties by blending with different fillers/compounds before film casting. In fact, both chitosan and pullulan have already been combined with several other biopolymers, [10][11][12][13][14][15] as well as inorganic nanoparticles, [16][17][18][19][20][21] aimed at preparing original biobased functional composite materials.…”