Exploring the Factors Affecting the Solubility of Chitosan in Water

Sogias, I., Khutoryanskiy, V. V. ORCID: https://orcid.org/0000-0002-7221-2630 and Williams, A. C. ORCID: https://orcid.org/0000-0003-3654-7916 (2010) Exploring the Factors Affecting the Solubility of Chitosan in Water. Macromolecular Chemistry and Physics, 211 (4). pp. 426-433. ISSN 1022-1352 doi: 10.1002/macp.200900385

Abstract/Summary

We explore the role of crystallinity and inter- or intramolecular forces in chitosan for its solubility in water and demonstrate the expansion of its solubility to a wider pH range. Due to its semicrystalline nature, derived mainly from inter- and intramolecular hydrogen bonds, chitosan is water-soluble only at pH < 6. In acidic conditions, its amino groups can be partially protonated resulting in repulsion between positively charged macrochains, thereby allowing diffusion of water molecules and subsequent solvation of macromolecules. We show that chemical disruption of chitosan crystallinity by partial re-acetylation or physical disruption caused by the addition of urea and guanidine hydrochloride broadens the pH-solubility range for this biopolymer.