Preparation and Grafting Functionalization of Self-Assembled Chitin Nanofiber Film

Abstract

Chitin is a representative biomass resource comparable to cellulose. Although considerable efforts have been devoted to extend novel applications to chitin, lack of solubility in water and common organic solvents causes difficulties in improving its processability and functionality. Ionic liquids have paid much attention as solvents for polysaccharides. However, little has been reported regarding the dissolution of chitin with ionic liquids. The author found that an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), dissolved chitin in concentrations up to~4.8 wt % and the higher contents of chitin with AMIMBr gave ion gels. When the ion gel was soaked in methanol for the regeneration of chitin, followed by sonication, a chitin nanofiber dispersion was obtained. Filtration of the dispersion was subsequently carried out to give a chitin nanofiber film. A chitin nanofiber/poly(vinyl alcohol) composite film was also obtained by co-regeneration approach. Chitin nanofiber-graft-synthetic polymer composite films were successfully prepared by surface-initiated graft polymerization technique. For example, the preparation of chitin nanofiber-graft-biodegradable polyester composite film was achieved by surface-initiated graft polymerization from the chitin nanofiber film. The similar procedure also gave chitin nanofiber-graft-polypeptide composite film. The surface-initiated graft atom transfer radical polymerization was conducted from a chitin macroinitiator film derived from the chitin nanofiber film.

Application of ionic liquids for the functional materialization of chitin

“…[71][72][73][74][75][76] In addition to the conventional top-down approach, [77][78][79][80][81][82][83] regenerative bottom-up approaches from solutions/gels with ILs have also been used to fabricate chitin nanofibers (ChNFs). 24,33,[84][85][86] ChNF dispersions were obtained by immersing the aforementioned 9.1-10.7 wt% chitin ion gels with AMIMBr in methanol at room temperature for 24 h to slowly regenerate chitin, followed by sonication (Fig. 4c).…”

“…10). 84 ChNF-graft-biodegradable polyester and polypeptide composite films were prepared by surface-initiated ring-opening graft polymerization of the corresponding cyclic monomers, that is, L-lactide (LA)/e-caprolactone (CL) and g-benzyl L-glutamate-NCA (BLG-NCA), initiated from hydroxy and amino groups, respectively, present on the self-assembled ChNF films. 99,100 Surface-initiated graft atom transfer radical polymerization (ATRP) from ChNF macroinitiators has also been conducted.…”

“…71–76 In addition to the conventional top-down approach, 77–83 regenerative bottom-up approaches from solutions/gels with ILs have also been used to fabricate chitin nanofibers (ChNFs). 24,33,84–86…”

Roll-to-Roll, Dual-Layer Slot Die Coating of Chitin and Cellulose Oxygen Barrier Films for Renewable Packaging

“…CNC film fabrication from suspension has utilized batch techniques such as spin coating and continuous processes such as slot die and gravure coating. Methods such as spray coating, regeneration from the gel, and layer-by-layer deposition have been used for coating ChNF suspensions (or chitin nanowhiskers) for biomedical, optical, and barrier applications. ,− Gravure and spray coatings often require multiple applications to achieve a desired, uniform thickness and can be challenging for suspensions with relatively high viscosity . Spin coating is not suitable to produce films continuously with a large area .…”

Preparation of Self-Assembled Chitin Nanofiber-Natural Rubber Composite Sheets and Porous Materials

“…We found in a subsequent publication that chitin self-assembles to form nanofiber dispersions by regeneration from the ion gel using methanol ( Figure 1 a). When the dispersion was filtered, the isolated self-assembled chitin nanofibers (CNFs) got highly entangled resulting in the formation of a film [ 13 , 14 , 15 ]. The dispersion has been used with other polymeric components such as cellulose, carboxymethyl cellulose, and poly(vinyl alcohol) to obtain CNF-containing composite materials [ 13 , 16 , 17 ].…”