Structure and properties of chitosan carboxymethyl ether

Гальбрайх²,

Gorbacheva³

et al. 2005

Self Cite

541.64.12:615.53 I. N. Gorbacheva, and A. O. Chernyshenko The structural features and reactivity in sulfation and carboxymethylation of chitin and chitosan isolated from different sources are correlated and improved methods of obtaining the corresponding derivatives are proposed. The mechanisms of formation and properties of SF-polyelectrolyte complexes based on chitosan and carboxymethylchitin are described. The properties of bulk-and surface-modified chitosan films are comparatively characterized.Problems of chemical transformations of cellulose were the most important direction of Z. A. Rogovins research, and many studies conducted at the Department of Chemical Fibre Technology and in the Problem Laboratory were dedicated to its modification, including in the form of fibres. However, other polysaccharides amylose, dextran, xylan, alginic acid were also always studied together with cellulose. In the 1970s, Z. A. Rogovin began studies of chitin polysaccharide and its most widespread deacetylated derivative chitosan: Chitin ChitosanThe importance of the plant natural polymer of cellulose is well known. Chitin, the crab, insect, and fungal structural polysaccharide discovered and described almost 200 years ago, remained in the shadows for many long years due to its dispersion in nature. Extensive studies of these polymers, primarily separated from shell-containing crab processing wastes were developed only a few decades ago due to statement of the problem of comprehensive assimilation of the oceans resources. Teams of chemists and polymer chemists, biologists, and microbiologists, physicians and pharmacists, and veterinarians and zoologists were involved in the studies of chitin and its derivatives and the most promising areas of application were determined almost immediately medicine, pharmaceutics, the food industry, agriculture, therapeutic cosmetology, and environmental protection (waste water treatment). The variety of the directions in use of articles made of chitin and its derivatives is not only due to their natural origin and consequently biocompatibility and biodegradability but also their good film-, fibre, and complexforming properties, biological activity, and for chitosan and other derivatives, solubility in available aqueous solvents, which facilitates processing them into articles.Moscow State Textile University.

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confidence: 99%

Advances in the Department of Chemical Fibre Technology in modification of chitin and chitosan

Гальбрайх²,

Gorbacheva³

et al. 2005

Self Cite

“…The high porosity of chitin in comparison to chitosan, high ordering of the supermolecular structure (65-80% degree of crystallinity) of chitosan and chitin from both sources, and the large size, defectiveness, and lower density of crystallites ofkrill chitosan were established as a result of a comparative study of the chemical structure, composition differences, and characteristics of the morphological and supermolecular structure of these preparations using a number of methods (x-ray structural analysis, sorption methods, microscopy, IR spectroscopy, differential thermal and elemental analysis, fractionation, viscometry, potentiometry, etc.) [8][9][10].The data obtained with these methods were used to explain the higher reactivity of chitin in comparison to chitosan and among the chitosans, in krill chitosan, and simultaneously the impossibility of using the starting polysaccharides without preliminary activation to obtain highly substituted and totally soluble derivatives. The effect of such treatments as dry grinding and grinding in liquid medium and inclusion with organic diluents, including diluents containing acids and bases, on the structural characteristics and reactivity of the polysaccharides in alkylation and esterification was investigated.…”

mentioning

confidence: 99%

“…The viscosity properties of dilute and concentrated solutions in a wide range of variation of the composition of the solvents, their pH, and ionic strength also characterize CMCS as a typical polyarnpholyte and chitosan and CMCT as polyelectrolytes [ 14,15]. The comparative study of concentrated solutions of chitosan and CMCT showed [15] that despite the high rigidity of the maeromolecules of CMCT, the presence of bulky substituents in it prevents formation of strong associates in solutions, so that solutions of chitosan of the same concentration have a higher cross-linking index and are resistant to shear strains.…”

mentioning

confidence: 99%

Synthesis and properties of water-soluble derivatives of chitin. A review

Gorbacheva²,

Гальбрайх³

1999

Self Cite

Concepts were formulated concerning the correlation of the structure and properties of an important class of biopolymers --aminopolysaccharides in aquatic organisms. Improved methods of obtaining water-soluble derivatives of chitin were developed, and their structure, physicochemicaI, and functional properties were characterized, including in the form of drugs, SF--PEC, and films.Cellulose polysaccharides and chitin are the two most widespread organic substances on Earth. The extent of the use and importance of cellulose are well known. Chitin is much less well known in this sense. One reason for this is that chitin is scattered in the oceans: crustacean shells are the main source. However, interest in chitin and its derivatives as objects for research and practical application has continuously increased in the past ten years. This is indicated by the increase in the number of publications and production volumes of these polysaccharides in industrially developed countries, primarily Japan and the USA. Russia is one of the countries that processes chitin and its best known derivative, chitosan, and the reserves potentially give Russia a leading position in the creation of these valuable polymers. We also note that depletion of the traditional sources --crab shells --can be compensated by the discovery of new sources such as krill shells, river crayfish, microscopic fungi, etc. [1,2].The product of deacetylation of chitin, chitosan, is the best known and investigated water-soluble derivative of chitin. The presence of ionogenic amino groups in chitosan determines many of its properties, including its consumer properties. Sulfated and carboxymethylated derivatives of chitin and chitosan are also of great interest. According to the published data, chitin and its derivatives can be used for different purposes, including for fabrication of fibres and films [3][4][5]. However, in consideration of the high cost and small production scales, using them for medical purposes, including as substances for pharmaceutical forms, suture and dressing materials, matrices for immobilization of biologically active substances, thrombusresistant coverings, selective membranes, etc., is most rational in this stage for assimilation of these polymers [6,7].The ash content and residual concentration of protein are usually the basic indexes for chitin and chitosan, while the degree of deacetylation (DA), i.e., the degree of conversion of chitin into chitosan, and the molecular weight (tool. wt.), which varies from 100,000 to 500,000 in commercial chitosans, are basic indexes for chitosan. The characteristics of the investigated crab and krill chitins and chitosans from different manufacturers are reported in Table 1. The high porosity of chitin in comparison to chitosan, high ordering of the supermolecular structure (65-80% degree of crystallinity) of chitosan and chitin from both sources, and the large size, defectiveness, and lower density of crystallites ofkrill chitosan were established as a result of a comparative study of the chemical...

Chemical modification of aquatic polysaccharides. A review

Gorbacheva²,

Гальбрайх³

1994

The effect of activating treatments (grinding and inclusion with organic solvents with acid or basic reagents) on the physical structure and reactivity of chitin and chitosan in esterification and alkylation reactions was investigated. Improved methods for preparation of water-soluble highly substituted chitosan sulfates (degree of substitution (DS) of up to 1.6) and carboxymethylated derivatives of chitin and chitosan (DS = 0.6-1.3) were proposed. The chemical and physical inhomogeneity of samples with different DS was evaluated. The solubility, acid-base properties of ionogenic groups, and viscosity properties of solutions of the derivatives were analyzed with respect to their polyampholytic nature. The pronounced biological activity of chitosan sulfates and the complexing and film-forming power of carboxymethylated products were used to determine promising areas of their practical use.