ISSN 0965-545X, Polymer Science, Ser. A, 2015, Vol. 57, No. 4, pp. 460–466. © Pleiades Publishing, Ltd., 2015. Original Russian Text © A.M. Bochek, N.R. Vokhidova, N.N. Saprykina, N.Sh. Ashurov, S.M. Yugai, S.Sh. Rashidova, 2015, published in Vysokomolekulyarnye Soedineniya. Ser. A, 2015, Vol. 57, No. 4, pp. 354–360. 460 At present, there has been a sufficient number of studies on how to synthesize polymer composite mate- rials with new functional properties via the introduc- tion of various kinds of nanoparticles into polymer matrixes in solvents or in melts [1–4]. In this context, polysaccharides are of interest owing to their biode- gradability and capacity to be extracted from the renewable raw material. In terms of the occurrence of polysaccharides in nature, chitin is second to cellu- lose. Chitin can be processed to yield chitosan, which is biocompatible with the human body and has found increasing use in agriculture, the food industry, and biomedicine [5–7]. Magnetic polymer nanocomposites are believed to be promising materials for the preparation of products with controlled magnetic characteristics along with a unique complex of properties that opens up wide opportunities for the development of new efficient catalysts, sensor systems, and preparations with high biological activity [8, 9]. For the biomedical use of nanoparticles, it is essential to fulfill some requirements: the formation of a stable colloid system in aqueous solutions and other biocompatible solvents or stabilization of nanoparticles in the polymer matrix to prevent their aggregation [10–12]. The introduction of silver and silver oxide nanopar- ticles into the cellulose or chitosan matrix endows it with bactericidal properties [13, 14] and extends the application areas of polysaccharides. The conditions of synthesis of chitosan composites with nanoparticles of noble metals—such as gold, silver, platinum, and palladium—are described in [15]. Metallopolymer complexes based on polyphenyleneamine and cobalt nanoparticles were studied in [16]. The synthesis of composites containing cobalt nanoparticles incorpo- rated into the matrix of the biodegradable polysaccha- ride chitosan is of interest from the scientific and prac- tical points of view. The aim of this study was to investigate the rheolog- ical properties of chitosan solutions after the addition of cobalt nanoparticles, to prepare composite films of chitosan with incorporated cobalt nanoparticles from these solutions, and to estimate the peculiarities of the morphologies of the composites. EXPERIMENTAL Chitosan solutions with dispersed cobalt nano- particles were prepared from the polysaccharide (chitosan isolated from chitin of cocoons of the mul- berry silkworm, Bombyx mori) with М = 3.8 × 10 4 and a degree of deacetylation of 63%, cobalt acetate Со(CН 3 СОО) 2 ⋅ 4H 2 O (reagent grade), ethanol, and deionized water. The isolation of chitin from Bombyx mori and the related chitosan was performed as described in [17]. The molecular weight of the polymer was measured via viscometry [18]. The degree of deacetylation of chito- san was determined via conductometric titration, and the total nitrogen content in chitosan was estimated through the Dumas method via sample combustion in a quartz tube under carbon dioxide [19]. The metal The Properties of Chitosan–Cobalt Nanoparticle Solutions and Related Composite Films A. M. Bochek a, *, N. R. Vokhidova b , N. N. Saprykina a , N. Sh. Ashurov b , S. M. Yugai b , and S. Sh. Rashidova b a Institute of Macromolecular Compounds, Russian Academy of Sciences, Bol’shoi pr. 31 (V.O.), St. Petersburg, 199004 Russia b Institute of Polymer Chemistry and Physics, Uzbekistan Academy of Sciences, ul. Abdully Kadyri 7b, 100128 Tashkent, Uzbekistan *e-mail: bochek@hq.macro.ru Received September 25, 2014; Revised Manuscript Received January 21, 2015 Abstract—Rheological properties of chitosan solutions containing aqueous and water–alcohol solutions of cobalt acetate and its nanoparticles have been studied. From these solutions, composite chitosan films with cobalt nanoparticles have been prepared. The morphological features of obtained films have been studied with the use of scanning electron microscopy with energy dispersive microanalysis, and their compositions have been determined. DOI: 10.1134/S0965545X15040033 COMPOSITES