Strengthening Cellulose Nanopaper via Deep Eutectic Solvent and Ultrasound-Induced Surface Disordering of Nanofibers

Abstract

The route for the preparation of cellulose nanofiber dispersions from bacterial cellulose using ethylene glycol- or glycerol-based deep eutectic solvents (DES) is demonstrated. Choline chloride was used as a hydrogen bond acceptor and the effect of the combined influence of DES treatment and ultrasound on the thermal and mechanical properties of bacterial cellulose nanofibers (BC-NFs) is demonstrated. It was found that the maximal Young’s modulus (9.2 GPa) is achieved for samples prepared using a combination of ethylene glycol-based DES and ultrasound treatment. Samples prepared with glycerol-based DES combined with ultrasound exhibit the maximal strength (132 MPa). Results on the mechanical properties are discussed based on the structural investigations that were performed using FTIR, Raman, WAXD, SEM and AFM measurements, as well as the determination of the degree of polymerization and the density of BC-NF packing during drying with the formation of paper. We propose that the disordering of the BC-NF surface structure along with the preservation of high crystallinity bulk are the key factors leading to the improved mechanical and thermal characteristics of prepared BC-NF-based papers.

Advances in green solvents for production of polysaccharide‐based packaging films: Insights of ionic liquids and deep eutectic solvents

“…The mechanical and UV-resistant properties of composite films could be tuned by changing the amount and type of lignin-containing cellulose nanofibers (LCNFs) (Liu et al, 2020). Batishcheva et al (2022) prepared films from bacterial cellulose nanofibers by dispersion (using or not ultrasound) of lyophilized bacterial cellulose in ethylene glycol-or glycerol-based DESs systems. The film with the best mechanical characteristics was achieved with the DESs (ChCl/ethylene glycol)-treated cellulose nanofibers and ultrasound application (Batishcheva et al, 2022).…”

“…Batishcheva et al (2022) prepared films from bacterial cellulose nanofibers by dispersion (using or not ultrasound) of lyophilized bacterial cellulose in ethylene glycol-or glycerol-based DESs systems. The film with the best mechanical characteristics was achieved with the DESs (ChCl/ethylene glycol)-treated cellulose nanofibers and ultrasound application (Batishcheva et al, 2022). This was interpreted as resulting from two factors: the first one is the small size of the ethylene glycol molecule in the DESs, which allows it to diffuse in the cellulose, and consequently, promote the formation of a disordered layer at the surface of microfibrils; the second one is the contribution of ultrasound, which can degrade the surface layer of the cellulose microfibrils and thus participate to its disorder (Batishcheva et al, 2022).…”

“…Batishcheva et al. (2022) prepared films from bacterial cellulose nanofibers by dispersion (using or not ultrasound) of lyophilized bacterial cellulose in ethylene glycol‐ or glycerol‐based DESs systems. The film with the best mechanical characteristics was achieved with the DESs (ChCl/ethylene glycol)‐treated cellulose nanofibers and ultrasound application (Batishcheva et al., 2022).…”

“…The film with the best mechanical characteristics was achieved with the DESs (ChCl/ethylene glycol)‐treated cellulose nanofibers and ultrasound application (Batishcheva et al., 2022). This was interpreted as resulting from two factors: the first one is the small size of the ethylene glycol molecule in the DESs, which allows it to diffuse in the cellulose, and consequently, promote the formation of a disordered layer at the surface of microfibrils; the second one is the contribution of ultrasound, which can degrade the surface layer of the cellulose microfibrils and thus participate to its disorder (Batishcheva et al., 2022). The effects of three DESs with different pH (acid, neutral, and alkaline) on cellulosic fiber structure and produced papers were studied (Mnasri et al., 2022).…”