Preparation and characteristics of reprecipitated chitin: a new morphological form easy to manipulate with versatile utility

With the object of effectively destroying the rigid crystalline structure of chitin and thereby preparing an amorphous form with enhanced reactivity, chitin was dissolved in methanol saturated with calcium chloride dihydrate and reprecipitated under appropriate conditions. Chitin in the solution was first precipitated in deionized water, and the mixture was subjected to dialysis followed by freeze-drying. As an alternative method, the chitin solution was directly dialyzed and freeze-dried. Judging from the appearances of the products, the latter method was much superior, giving rise to the formation of highly fluffy cotton-like chitin. Compared to β-chitin, α-chitin was suitable as a starting material because of the adequate solubility in the solvent system. The resulting reprecipitated chitin exhibited higher reactivity as confirmed by the adsorption of copper(II) and acetylation reaction. The method was quite simple and convenient to prepare reprecipitated chitin that will have high potential as a new form from the practical viewpoint.