Chitosan solution properties

Let us consider now the case of a specific ionic polysaccharide. The unique properties of complexes of the cationic chitosan with non-ionic sorbitan esters provides an interesting example. Grant and co-workers (2006) have established that mixtures of chitosan and surfactant form emulsion-like solutions and/or creams, where the surfactant component is present as droplets or micelle-like particles and the chitosan solution acts as the system s continuous phase. It was established that the length and the degree of saturation of the surfactant hydrocarbon chain have a significant impact on the development of the chitosan-surfactant complexes. Moreover, an optimal distance between the chitosan s protonated amine groups is required for effective interactions to occur between the polysaccharide and the sorbitan esters. 

This method used the physicochemical properties of polymers like chitosan, which is insoluble in alkaline pH medium and therefore precipitates/coa-cervates when it comes in contact with alkaline solution. Particles are produced by blowing chitosan solution into an alkali solution like NaOH using a compressed air nozzle to form coacervate droplets (Agnihotri et al. 2004). 

Anthonsen, M.W., Varum, K.M., and Smidsrod, O. 1993. Solution properties of chitosans Conformation and chain stiffness of chitosans with different degrees of V-acetylation. Carbohydr. Polym. 22, 193-201. 

Hwang, J. K., and Shin, H. H., Rheological properties of chitosan solutions, Korea-Aust. Rheol.J., 12(3/4), December (2000), 175-179. 

A. Gamzazade, V. Slimak, A. Skljar, E. Stykova, S.S. Pavlova, S. Rogo n, Investigation of the hydrodynamic properties of chitosan solutions, Acta Polym. 36 (1985) 420-424. 

In contrast to chitin, the presence of free amino groups along the chitosan chains allows this macromolecule to dissolve in dilute aqueous acidic solvents through the protonation of these groups and the formation of the corresponding chitosan salt. It is therefore important to realize that the polyelectrolyte character of chitosan influences its solution properties. 

Sorlier R, Viton C., Domard A., Relation between solution properties and degree of acetylation of chitosan Role of aging, Biomacromolecules, 3,2002, 1336-1342. 

Kienzle-Sterzer C., Rodriguez-Sanchez D., Rha C., Solution properties of chitosan Chain conformation, Chitin, Chitosan, Relat. Enzymes, Proceedings of the Joint US-Japan. Seminar on Advances in Chitin, Chitosan, Related Enzymes, 1984,... 

Chitosan powder used in this research was furnished by Funakoshi Co., Ltd. and had 85% deacetylation property and a viscosity of 5-20 cp. To prepare the chitosan film, 4g of chitosan was first dispersed into 100 mL of distilled water and stirred for 30 min to make it well infiltrated. Four kinds of acid— acetic acid, formic acid, butyric acid, and propionic acid—were used as solvents (Sakurai et al. 1984). Four milliliters of each solvent was added to the chitosan solution individually and mixed for 24 h and then the solution was cast in a petri dish. The solvent was evaporated at room temperature to form the cast film. Each chitosan film was immersed into 4% of sodium hydroxide for 24h to neutralize the films and then washed well with distilled water. The resultant films were elongated up to two times of their original size under steam. 

Sandford, P. A. and A. Steinnes. 1991. Biomedical apphcations of high-purity chitosan. Physical, chemical and bioactive properties. In Water-Soluble Polymers, Synthesis, Solution Properties arul Applications, American Chemical Society, Symposium Series, eds. S. W. Shalaby, C. L. McCormick, and G. B. Butler, Vol. 467, pp. 430-445. Washington, DC ACS. 

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