The production of cellulose/chitosan blends in alkyl imidazolium ionic liquids (ILs) was studied in this work. Selected organic solvents, such as dimethyl sulfoxide, ethyl acetate, and diethyl ether, were used as cosolvents. The addition of cosolvents decreased the viscosity of cellulose/chitosan solutions in ILs and facilitated the dissolution of polysaccharides, thereby decreasing the and polymer aggregates sizes in the solutions. The cellulose/chitosan films were produced from the studied solutions. The presence of one of cosolvent and ILs in the blended films was confirmed by FTIR spectroscopy. The blended film is stronger than pure cellulose film, and the addition of cosolvents has an influence on its mechanical properties. 1. Introduction Since 2002 ILs have been established as direct solvents for cellulose dissolution [1, 2]. The advantages of using ILs for cellulose processing have been widely studied over the last decade [1, 3, 4]. Cellulose films and fibers produced from ILs solutions could be modified to improve their water absorption, dyeability, and mechanical and bactericidal properties [5–7]. It was found that ILs could dissolve not only cellulose but other carbohydrates [8], chitin, chitosan [9–11], and starch [12] proteins such as Bombyx mori silk fibroin [13, 14] and wool keratin [15]. It is possible to obtain unique mixtures of polymers in ILs, for example, mixtures of cellulose, starch, and lignin [16]. Binary blends of natural polymers such as cellulose and chitosan are promising systems for creating new polymer materials like blended films, fibers, and sponges. One of the main problems encountered with the blending of two polymers is its compatibility, which is dependent upon the formation of inter- and intramolecular interaction between the macromolecules. Compared to cellulose, the reactivity of chitosan is more versatile due to the presence of NH2 groups [17]. The blending of these two polymers could be a prospective way to their modification and improving the properties of the final products. The similarity in the chemical structures of chitosan and cellulose predicts their compatibility and the possibility of their homogeneous blending. Cellulose, as most of the naturally occurring polysaccharides, is acidic in water media [18], whereas chitosan is a basic polysaccharide [19]. The research into cellulose-chitosan blending shows great potential for the materials that could be obtained from this method. The intramolecular interactions between molecules of both polymers were confirmed [19], and cellulose/chitosan films obtained
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