ABSTRACT:The phase behavior of blends containing chitosan with poly(vinyl-alcohol) (PVA) and poly(2-hidroxyethyl methacrylate) (P2HEM) was analyzed. Blends were obtained by casting from acetic acid solution (HAc) and 1,1,1,3,3,3 hexafluoro-2-propanol (HF2P) and studied by DSC, FT-IR, and TGA. The phase behavior of the blends of chitosan with PVA and P2HEM, studied by DSC, shows that the systems behave as one-phase systems in HAc as well as in HF2P according to the DSC results. According to the results of FT-IR analyses of the different absorptions of the blends, relative to the pure components, they show an important shift that is considered evidence of an interaction between the components of the blends. The thermogravimetric analysis of the blends and the pure components shows that the temperature for thermal degradation of the blends is higher that that of the pure components, irrespective of the solvent casting from which the mixture was obtained. These results are interpreted as the formation of a new product that corresponds to a compatible polymer blend. The compatibilization of these systems is attributed to strong interactions, like hydrogen bonds formation between the functionalized polymers and chitosan, due to the presence of interacting functional groups in all the polymers studied.
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This mini-review deals with the miscibility behavior of two biopolymers, chitosan, and alginate. It is well known that the miscibility in multifunctional polymers blends is favored due to specific interactions, which origin a negative heat of mixing. Particular interest is focused on functionalized polymers because they are the most suitable way to obtain interacting polymers, producing a single-phase material. Due to the polyfunctionality of chitosan (CS) and other biopolymers, they can be taken into account as a basis of a strongly interacting polymer. They would allow obtaining compatible polymeric materials. For this reason, blends containing CS with different vinyl polymers have been studied. The most significant polymeric blends with these natural polymers will be analyzed in this review. Chitosan is obtained from the biopolymer chitin through sequential processes of demineralization, deproteinization, and deacetylation. The native chitin is obtained by direct separation from the marine crustaceans shell, abundant on the sea coasts. Some classic results that relate to the polymeric blends containing amphiphilic polymers will be discussed. Another biopolymer of the coast is Sodium Alginate (SA). Alginate also allows the formation of compatible polymer blends. Results in this regard will also be analyzed in this review.
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