Dissolution and regeneration behavior of chitosan in 3-methyl-1-(ethylacetyl)imidazolium chloride

Abstract

3-methyl-1-(ethylacetyl)imidazolium chloride ([EtMIM]Cl), was synthesized for chitosan dissolution, and the dissolution and regeneration behaviors of chitosan in [EtMIM]Cl were thoroughly investigated. The solubility of chitosan in [EtMIM]Cl was measured at temperatures ranging from 40 o C to 110 o C, based on which the thermodynamic parameters of chitosan in [EtMIM]Cl were calculated. The polarizability and hydrogen bond accepting ability was determined by solvatochromic UV/vis spectroscopy. The regenerated chitosan from [EtMIM]Cl by adding methanol was characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Density functional theory (DFT) computations were performed to study the interactions between [EtMIM]Cl and chitobiose. Five kinds of hydrogen bonds, C-H/O, O-H/O, O-H/Cl, C-H/Cl, N-H/Cl were found, suggesting strong interactions between [EtMIM]Cl and chitobiose. In particular, the oxygen atom and the active methylene group of carboxylic ester in [EtMIM] + , formed strong hydrogen bonding with chitobiose. The molecular simulation results indicated that both the Cl − anions and [EtMIM] + cation played important roles in the chitosan dissolution process, by the disruption of native hydrogen bonds of chitosan.

Ionic Liquids in Drug Delivery

“…Due to ILs' unique properties and the wide variety of intermolecular interactions afforded, these solvents have proven to be also adequate solvents for biopolymers dissolution, allowing the substitution of the use of organic solvents in this field. In this sense, the dissolution of proteins [76,77], and more extensively polysaccharides (e.g., cellulose [78], chitosan [79,80], chitin [81], or guar gum [82]), has been reported using mostly imidazolium-based ILs, as summarized in Table 3. Despite the promising results reported, biopolymers' dissolution is usually performed at moderately high temperatures; thus, to prevent the biopolymers' decomposition or incomplete dissolution, the dissolution conditions should be carefully evaluated and the IL properly designed for this purpose.…”

From biopolymer dissolution to CO2 capture under atmospheric pressure - A molecular view on biopolymer@Ionic liquid materials

“…However, these solvents are generally volatile, toxic, corrosive, and difficult to recover. In addition, the use of concentrated strong acids can reduce the molecular weight of biopolymer, by polymer chain fragmentation (Wang et al, 2010;Xu et al, 2016). Consequently, it is imperative to discover effective and sustainable solvents for Cs and Ct dissolution.…”