Homogeneous synthesis and characterization of chitosan ethers prepared in aqueous alkali/urea solutions. (1st April 2018)

• Record Type: Journal Article
• Authors: Cao, Jinfeng; You, Jun; Zhang, Lina; Zhou, Jinping
• Is Part Of: Carbohydrate polymers. Volume 185(2018)
• Page Start: 138
• Page End: 144
• Publication Date: 2018-04-01
• Subjects: Chitosan ethers -- Aqueous alkali/urea solution -- Homogeneous synthesis -- Reactivity -- Degree of substitution; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2018.01.010
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Etherification of chitosan was conducted in aqueous LiOH/KOH/urea solutions. Degree of substitution of the chitosan ethers could be easy controlled. Trimethyl chitosan could be prepared through a one-step reaction. Both O -substituted and N -substituted occurred in the etherification of chitosan. Abstract: The etherification of chitosan dissolved in aqueous LiOH/KOH/urea solutions was conducted for the first time. The structure and solution properties of the chitosan ethers were characterized using FT-IR, NMR, SEC-LLS, elemental analysis, and ζ-potential measurement. Chitosan ethers with different degrees of substitution (DSs) were obtained by adjusting the molar ratio of the etherifying agent to N -acetylglucosamine unit (AGU) of chitosan. The total DS for methyl chitosan (MCh) increased from 1.17 to 2.25, and trimethyl chitosan (TMCh) was obtained with DS N -trimethyl as high as 0.48. The total DS for carboxymethyl chitosan (CMCh) was in the range 0.75–1.45. Both N -substitution and O -substitution were observed, and the OH groups at C-6 displayed relative higher reactivity than the OH groups at C-3. In comparison with the traditional methods and solvents, aqueous alkali/urea solutions proved to be a stable and more homogeneous medium for preparing chitosan ethers with higher DS through a one-step reaction.