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Inks for 3D printing were prepared by dispersing bacterial cellulose nanofibers (CNF) functionalized with methacrylate groups in a polymerizable deep eutectic solvent (DES) based on choline chloride and acrylic acid with water as a cosolvent. After 3D printing and UV-curing, the double-network composite gel consisting of chemically and physically crosslinked structures composed from sub-networks of modified CNF and polymerized DES, respectively, was formed. The rheological properties of inks, as well as mechanical and shape memory properties of the 3D-printed gels, were investigated in dynamic and static modes. It was shown that the optimal amount of water allows improvement of the mechanical properties of the composite gel due to the formation of closer contacts between the modified CNF. The addition of 12 wt% water results in an increase in strength and ultimate elongation to 11.9 MPa and 300%, respectively, in comparison with 5.5 MPa and 100% for an anhydrous system. At the same time, the best shape memory properties were found for an anhydrous system: shape fixation and recovery coefficients were 80.0 and 95.8%, respectively. [ABSTRACT FROM AUTHOR]

Two polymerizable ionic liquids (or monomeric ionic liquids, mILs) namely 1-butyl-3-methylimidazolium and choline acrylates ([C4mim]A and ChA, respectively) were synthesized using the modified Fukumoto method from corresponding chlorides. The chemical structure of the prepared mILs was confirmed with FTIR and NMR study. Investigation of the thermal properties with DSC demonstrates that both mILs have a Tg temperature of about 180 K and a melting point around 310 K. It was shown that the temperature dependence of FTIR confirm the Tg to be below 200. Both mILs exhibited non-Newtonian shear thinning rheological behavior at shear rates >4 s−1. It was shown that [C4mim]A is able to dissolve bacterial cellulose (BC) leading to a decrease in its degree of polymerization and recrystallisation upon regeneration with water; although in the ChA, the crystalline structure and nanofibrous morphology of BC was preserved. It was demonstrated that the thixotropic and rheological properties of cellulose dispersion in ChA at room temperature makes this system a prospective ink for 3D printing with subsequent UV-curing. The 3D printed filaments based on ChA, containing 2 wt% of BC, and 1% of N,N′-methylenebisacrylamide after radical polymerization induced with 1% 2-hydroxy-2-methylpropiophenone, demonstrated Young's modulus 7.1 ± 1.0 MPa with 1.2 ± 0.1 MPa and 40 ± 5% of strength and ultimate elongation, respectively. [ABSTRACT FROM AUTHOR]

Cellulose nanofibers (CNF) produced by bacterial were functionalized along the surface with 3-(trimethoxysilyl)propyl methacrylate (TMSPM). The chemical and crystalline structure of the material was confirmed with NMR, FTIR, EDX and XRD methods. Modified CNF were used as a crosslinker and reinforcer for polymerizable deep eutectic solvent (DES) based on acrylic acid and choline chloride. Dispersions of modified nanofibers in DES were applied as UV-curable ink for 3D printing. It was shown that shielding of -OH groups of the cellulose surface with TMSPM increased the quality of 3D printed filaments due to reduced CNF agglomeration. At the same time, surface methacrylic groups copolymerize with acrylic acid forming crosslinked ion gel. Elastic moduli of the prepared ion gels were identical to those of gels based on unmodified CNF and crosslinked with N,N'-methylenebisacrylamide. However, strength and the ultimate elongation of the material prepared in this work were 1.05 ± 0.08 MPa at 2700% that is significantly higher than those of the material prepared with unmodified CNF. [ABSTRACT FROM AUTHOR]

Chitosan (CS) films containing deep eutectic solvent (DES) based on malonic acid (MA) and choline chloride (ChCl) were successfully prepared by solution casting method by using DES content ranging from 0 to 82 wt%. A strong interaction of CS with the components of DES was demonstrated by analyses of water sorption isotherms, atomic force microscopy and FTIR results. The plasticizing effect of the MA and ChCl mixture on the CS matrix was shown by static bulk mechanical measurements, thermal analysis and quantitative nanomechanical mapping (QNM). Elongation at break increased from 3 to 62% at increase of DES content from 0 to 67 wt%, while further increase of DES content led to the decreasing of maximal elongation. Introduction of DES into CS films led to the appearance of glass transition temperature in the region +2 - -2.3 °C. QNM results indicated homogeneity of the films containing up to 75 wt% of DES. [ABSTRACT FROM AUTHOR]

3D-printing of stimuli-responsible electroactive gels containing biopolymers, such as cellulose nanocrystals (CNC), is a prospective area of material science. Deep eutectic solvents (DES) have shown a potential interest for applications in electroactive materials as well as for processing of cellulose. In this work, CNC obtained by two methods of processing microcrystalline cellulose were used for preparation of inks containing 6–15 wt% of CNC in polymerizable DES based on choline chloride/acrylic acid. The impact of rheological properties of the inks on 3D-printability was evaluated. The effect of CNC content on the morphology and ionic conductivity of 3D-printed electroactive composite gels was investigated using atomic force microscopy and impedance spectroscopy measurements. The potential application of the obtained materials for designing of a 3D-printed tactile sensor have been demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, a novel approach is demonstrated for 3D-printing of bacterial cellulose (BC) reinforced UV-curable ion gels using two-component solvents based on 1-butyl-3-methylimidazolium chloride or choline chloride combined with acrylic acid. Preservation of cellulose's crystalline and nanofibrous structure is demonstrated using wide-angle X-ray diffraction (WAXD) and atomic force microscopy (AFM). Rheological measurements reveal that cholinium-based systems, in comparison with imidazolium-based ones, are characterised with lower viscosity at low shear rates and improved stability against phase separation at high shear rates. Grafting of poly(acrylic acid) onto the surfaces of cellulose nanofibers during UV-induced polymerization of acrylic acid results in higher elongation at break for choline chloride-based compositions: 175% in comparison with 94% for imidazolium-based systems as well as enhanced mechanical properties in compression mode. As a result, cholinium-based BC ion gels containing acrylic acid can be considered as more suitable for 3D-printing of objects with improved mechanical properties due to increased dispersion stability and filler/matrix interaction. [ABSTRACT FROM AUTHOR]

Two different choline chloride based deep eutectic solvents (DES) were tested for the separation of azeotropic mixture of n -hexane and ethanol via liquid-liquid extraction. The simplest mixtures of choline chloride with dibasic acids: oxalic (DES1) or malonic (DES2) with molar ratio 1:1 were used. The selected DESs were characterized by differential scanning calorimetry (DSC). Extraction experiments were conducted with pseudo-ternary mixtures n -hexane–ethanol–DES. Tie-lines were obtained at temperatures 293.15 K, 313.15 K and atmospheric pressure. The extraction performance of DES was characterized with solute distribution coefficients and values of selectively for ethanol. It has been shown that the most successful component for the separation of a mixture of n -hexane-ethanol is water. It was found that DES1 is more effective then DES2 for extraction of ethanol. The higher efficiency of separation of DES as compared to conventional ionic liquids (IL) makes it possible to consider them as an alternative promising solution in the separation of multicomponent mixtures. Experimental data was fitted using the nonrandom two liquids (NRTL) model. [ABSTRACT FROM AUTHOR]

Plasticized chitosan films with high content (67–82 wt%) of natural deep eutectic solvent (NADES) based on citric acid and choline chloride were prepared by solution casting method. The thickness of films was 19 ± 3 μm. The self-healing and water vapor bending movement of prepared films were demonstrated. Maximal mechanical characteristics of 84% elongation at break and 18 MPa strength, were achieved for a film containing 67 wt% of NADES. The formation of hydrogen bond network in the chitosan film due to replacement of citric acid with NADES (citric acid/choline chloride) was observed with FTIR. It is proposed that this network is responsible for self-healing ability of the chitosan–citric acid–choline chloride films. Structure, morphology and thermal properties of the prepared films are also discussed. • Chitosan (CS) was plasticized with citric acid/choline chloride (NADES). • Maximal elasticity for film with 67 wt% of NADES was found. • Self-healing ability of fully bio-based elastic CS/NADES film was demonstrated. • CS/NADES film shows fast and reversible water vapor-induced movement. • High NADES content (75 and 82 wt%) leads to inhomogeneity of films' structure. [ABSTRACT FROM AUTHOR]

• CS/DES polymer electrolyte demonstrate the ionic conductivity of 2.5 mS cm−1. • Electrochemical stability window of CS/DES polymer electrolyte is 1.6 V. • CS/DES-PPy electrode was prepared via vapor phase polymerization. • The specific capacitance of assembled flexible supercapacitor reaches 194 mF cm−2. The aim of this work is demonstration of a solid polymer electrolyte based on choline chloride/lactic acid deep eutectic solvent (DES) entrapped in chitosan (CS) matrix as potential separator for electrochemical energy storage devices. This full bio-based material demonstrates the high ionic conductivity up to 2.5 mS cm−1 and electrochemical stability window of 1.6 V. The polypyrrole-based film electrodes were prepared using CS/DES films as a supporting matrix for vapor phase polymerization of pyrrole. That allows assembling of a supercapacitor with the specific capacitance of 194 mF cm−2 at the current density of 1 mA cm−2. [ABSTRACT FROM AUTHOR]