Ionic Conductivity and Structure of Chitosan Films Modified with Lactic Acid-Choline Chloride NADES

Abstract

The natural deep eutectic solvent (NADES) based on choline chloride (ChCl) and lactic acid (LA) was used for the preparation of chitosan (CS) films by the solution casting method. The content of NADES in films was from 0 to 82 wt%. The impact of NADES on the morphology and crystalline structure of films was investigated using scanning electron microscopy as well as wide-angle and small-angle X-ray scattering. The experimental results allow to propose CS chains swelling in NADES. FTIR spectroscopy confirms the interactions between CS and NADES components via the formation of hydrogen and ion bonds. The thermal properties of the composite films were studied by simultaneous thermogravimetric and differential thermal analysis. Thermomechanical analysis demonstrated appearance of two transitions at temperatures between −23 and −5 °C and 54–102 °C depending on NADES content. It was found that electrical conductivity of film with 82 wt% of NADES reaches 1.7 mS/cm. The influence of the composition and structure of films on the charge carriers concentration and their mobility is discussed.

Effect of Curcumin Addition on the Properties of Biodegradable Pectin/Chitosan Films

“…Chitosan is a kind of cationic polysaccharide obtained by deacetylation of chitin extracted from crustacean shells [ 10 ], and it has been studied in the field of food active packaging for its sustained drug release [ 11 ], biodegradability, bacteriostatic and non-toxic properties [ 12 ]. However, the disadvantages such as poor mechanical properties, poor hydrophilic and narrow bacteriostatic spectrum limit its applications.…”

“…Therefore, it is necessary to overcome its hydrophilic and mechanical property weaknesses. A deep eutectic solvent (DES) is a liquid formed by the interaction of two or more components through strong hydrogen bonds, in which the melting temperature is much lower than that of any of the single components [ 12 , 13 ]. DES is not only cheap, but also has high solubility, low toxicity, low volatility, and good bio-degradability, which has been widely used in bioactive extraction [ 14 ], reaction media, melt processing [ 15 ], and organic synthesis [ 16 ].…”

Understanding Electrodeposition of Chitosan–Hydroxyapatite Structures for Regeneration of Tubular-Shaped Tissues and Organs

“…The FTIR spectrum of lactic acid showed characteristic absorption bands at 1733 (CO double bound stretch characteristic for carboxylic acid group) and 1415 cm −1 (C–H bend) ( Figure 1 Da). The bands at 1226, 1126, and 1040 cm −1 were assigned to C–C and C–O stretching [ 27 ]. None of the studied inner surfaces showed bands around 1733 cm −1 ( Figure 1 Db).…”

Investigation of the influence of natural deep eutectic solvents (NaDES) in the properties of chitosan-stabilised films

“…Only little research on the field of chitosan dissolution directly into an aqueous solution of NaDES or their components 42,51 has been conducted and should be investigated further, as the low solubility of the polymer in a number of common solvents constitutes a major drawback. Our work was mainly focused on the preparation of the films and the comparison of their properties, therefore the full capacity of NaDESs' capability of dissolving chitosan is an aspect worthy of future investigation.…”

“…Furthermore, a new small shoulder appears at 1521 cm À1 , corresponding to the ammonium cation, verifying the formation of chitosan lactate. [41][42][43] In the spectrum of F/bet:LA NaDES (Fig. 6) the bands at 2923 and 2854 cm À1 are very strong, while the 3412 cm À1 peak is significantly weaker and the -OH peak is negligible, indicative of a smaller amount of the acid in its neutral form.…”