Plasticized Cellulosic Films by Partial Esterification and Welding in Low-Concentration Ionic Liquid Electrolyte

Abstract

Alternatives to petroleum-based plastics are of great significance not only from the point of view of their scientific and practical impact but to reduce the environmental footprint. Inspired by the composition and structure of wood’s cell walls, we used phenolic acids to endow cellulosic fibers with new properties. The fiber dissolution and homogeneous modification were performed with a recyclable ionic liquid (IL) (tetrabutylammonium acetate ([N4444][OAc]):dimethyl sulfoxide) to attain different levels of reaction activity for three phenolic acids (p-hydroxybenzoic acid, vanillic acid, and syringic acid). The successful autocatalytic Fischer esterification reaction was thoroughly investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and nuclear magnetic resonance spectroscopy (13C CP-MAS, diffusion-edited 1H NMR and multiplicity-edited heteronuclear single quantum coherence). Control of the properties of cellulose in the dispersed state, welding, and IL plasticization were achieved during casting and recrystallization to the cellulose II crystalline allomorph. Films of cellulose carrying grafted acids were characterized with respect to properties relevant to packaging materials. Most notably, despite the low degree of esterification (DS < 0.25), the films displayed a remarkable strength (3.5 GPa), flexibility (strains up to 35%), optical transparency (>90%), and water resistance (WCA ∼ 90°). Moreover, the measured water vapor barrier was found to be similar to that of poly(lactic acid) composite films. Overall, the results contribute to the development of the next-generation green, renewable, and biodegradable films for packaging applications.

Biodegradable Cellulose Nanofibril Films with Active Functionality for Food Packaging Applications

“…Compared to CNF, esterification significantly ( p < 0.05) decreased specific tensile strength of modified films; as hydroxyl groups in CNF films were replaced with organic acids, the hydrogen bonding between linear cellulose chains was lost, leading to an increase in amorphousness and a significant ( p < 0.05) reduction in tensile strength. This reduction in tensile strength agrees with other studies, where surface modification of polysaccharides with organic acids decreased their tensile strength . In contrast, upon surface esterification of the benzoic acid derivatives syringic and vanillic acid on precast CNF films no significant decrease in specific tensile strength was noted .…”

“…This reduction in tensile strength agrees with other studies, where surface modification of polysaccharides with organic acids decreased their tensile strength. 23 In contrast, upon surface esterification of the benzoic acid derivatives syringic and vanillic acid on precast CNF films no significant decrease in specific tensile strength was noted. 19 This difference between the effects of benzoic acid derivatives and cinnamic acid and its derivatives on mechanical strength of films can be attributed to the differences in chain length as well as the P.R.…”

Thermoplastic “All-Cellulose” Composites with Covalently Attached Carbonized Cellulose

“…The need for high-quality, biodegradable materials from renewable sources is evident, considering the plastic waste accumulation and the depleting fossil reserves. Cellulose is an appealing candidate for the development of future materials due to its biocompatibility, biodegradability and chemical modifiability. − However, due to the inherent H-bonding network and the tight fibrous structure of cellulose, it cannot be melt-processed and it is basically nonsoluble in traditional solvents, which have restrained the application of cellulose-based materials. , Lately, ionic liquids (ILs) that efficiently dissolve cellulose by disrupting the H-bonding have been widely applied for cellulose modification and processing. ,,− …”

Plant‐Based Structures as an Opportunity to Engineer Optical Functions in Next‐Generation Light Management

“…High transparency/low haze films can be produced by partial cellulose dissolution followed by regeneration or derivatization. [ 71 ] In both cases, the interactions between macroscale cellulosic fibers are disrupted, followed by regeneration in a nonsolvent bath to give homogenous materials with a minimal number of voids. [ 72 ] Specific solvents, such as ionic liquids (ILs), NaOH/Urea, N‐methyl morpholine‐N‐oxide (NMMO), N, N‐dimethylacetamide/LiCl (DMAc/LiCl), tetrabutylammonium fluoride/dimethyl sulfoxide (DMSO), metal‐complex solutions, and molten inorganic salt solutions, can be used to dissolve cellulose.…”