Effect of urea addition on chitosan dissolution with [Emim]Ac-Urea solution system

Area of Science:

• Materials Science
• Polymer Chemistry
• Physical Chemistry

Background:

• Chitosan, a versatile biopolymer, requires effective dissolution for homogeneous chemical modification.
• Traditional solvents often have limitations in dissolving chitosan efficiently and uniformly.

Purpose of the Study:

• To design and investigate a novel solvent system for chitosan dissolution using [1-ethyl-3-methylimidazolium acetate] ([Emim]Ac) and urea.
• To elucidate the interactions between [Emim]Ac, urea, and chitosan at a molecular level.

Main Methods:

• Characterization of physicochemical properties of [Emim]Ac and [Emim]Ac-urea solutions.
• Spectroscopic analysis (NMR, FTIR) to determine [Emim]Ac-urea interactions.
• Chitosan dissolution performance evaluation.
• Density Functional Theory (DFT) simulations to model molecular interactions.

Main Results:

• Strong hydrogen bonds were confirmed between [Emim]Ac and urea via NMR and FTIR, indicated by significant chemical shift changes.
• [Emim]Ac-urea solutions effectively dissolved chitosan, enabling homogeneous modification.
• DFT simulations revealed multiple hydrogen bonding interactions (CH/O, CH/N, NH/O, NH/N) between [Emim]Ac, urea, and chitosan's chitobiose units.

Conclusions:

• The [Emim]Ac-urea system is a promising solvent for chitosan dissolution and homogeneous modification.
• Understanding the hydrogen bonding network is crucial for designing efficient chitosan solvent systems.
• This research provides valuable insights for developing advanced materials from chitosan.