Determining the influence of N-acetylation on water sorption in chitosan films.
Water absorption in chitosan rapidly increases when the deacetylation degree decreases between 85 and 45%. This seems to contradict the fact that water absorption in chitin is much lower than that of chitosan. The aim of this paper is to understand this feature by measuring the main parameters affecting equilibrium water content. Since swelling capacity depends on the water-polymer interaction, the Flory Huggins interaction parameter was evaluated, finding small or null dependence on the deacetylation degree. Other factor influencing elastic energy is chain stiffness related to the elastic modulus that was measured as a function of deacetylation degree. Besides, crystalline structure was measured by X-ray diffraction patterns as a characteristic of cross-linking density. These observations led us to conclude that the instability of crystals during the swelling process increases with decreasing deacetylation degree, explaining the high equilibrium water content of low deacetylation chitosans.
Center for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Cno.de Vera s/n, 46022 Valencia, Spain. Electronic address: agamiz@upvnet.upv.es.
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Gámiz-González
Center for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Cno.de Vera s/n, 46022 Valencia, Spain.
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Piskin
Physics Department, National Technical University of Athens, Athens, Greece.
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Pandis
Physics Department, National Technical University of Athens, Athens, Greece.
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Chatzimanolis-Moustakas
Physics Department, National Technical University of Athens, Athens, Greece.
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Kyritsis
Departamento de Física Aplicada-IDF, Universitat Politècnica de Vàlencia, 46022 Valencia, Spain.
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Marí
Center for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Cno.de Vera s/n, 46022 Valencia, Spain; Center in Bioengineering, Biomaterials and Nanomedicine of (CIBER-BBN), Valencia, Spain.
J L Gómez
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Ribelles
Center for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Cno.de Vera s/n, 46022 Valencia, Spain; Center in Bioengineering, Biomaterials and Nanomedicine of (CIBER-BBN), Valencia, Spain.
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Vidaurre
D065966:Absorption, Physicochemical; D000107:Acetylation; D048271:Chitosan / Q000737:chemistry*; D055595:Mechanical Phenomena; D009584:Nitrogen / Q000737:chemistry*; D014835:Volatilization; D014867:Water / Q000737:chemistry*
D014867:Water; D048271:Chitosan; D009584:Nitrogen
Chain stiffness; Chitosan; Crystallinity; Deacetylation degree; Flory Huggins parameter; Water absorption