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Ionic conductive gels are widely sought after for applications that require reliable ionic conduction and mechanical performance under extreme conditions, which remains a grand challenge. To address this limitation, water‐induced hydration interactions are deliberately controlled within the ionic liquid (IL)‐based conductive gels (ionogels) to achieve all‐round performance. Specifically, the competitive interactions between IL, water and cellulose nanofibrils (CNF) are balanced to preserve the nanoscale morphology of CNF while avoiding its dissolution. As a result, both mechanical performance and ionic conductivity of the resultant ionogel are synergistically enhanced. For instance, an ultra stretchable ionogel (up to 10250 ± 412% stretchability) with both high toughness (21.8 ± 0.9 MJ m−3) and ionic conductivity (0.70 ± 0.06 S m−1) is achieved. Furthermore, multimodal sensing functions (strain, compression, temperature, and humidity) are realized by assembling the ionogel as a skin‐like membrane. Due to the low volatility of IL and its strong interaction with water, the ionogel maintains an excellent performance at either ultra‐low temperature (−45 °C), high temperature (75 °C) or low humidity environment (RH < 15%), demonstrating superb anti‐freezing and anti‐drying performance. Overall, a simple yet versatile strategy is introduced that leads to environmentally resilient ionogels to meet the requirements of next‐generation electroactive devices. [ABSTRACT FROM AUTHOR]

Conversion economics, risk, and fi nancial analyses for an industrial facility manufacturing cellulose micro- and nanofibrils (CMNF) from wood pulp is presented. Process data is based on mass and energy balances from a pilot facility in the University of Maine. Here, CMNF is produced from untreated wood pulp by using disk refining, with an assumed production capacity of 50 t (dry metric ton equivalent) per day. Stand-alone and co-location manufacturing facilities were simulated and assessed. Minimum product selling prices (MPSP, estimated to achieve a 16% hurdle rate) for different scenarios ranged from USD 1893/t CMNF to USD 2440/t CMNF (dry equivalent). Pulp and energy consumption were identified as major cost drivers. Consequently, it was found that the use of alternative feedstock, in addition to co-location configuration, can reduce MPSP by 37%. Since estimated MPSP of CMNF is lower than cellulose nanocrystals (CNC) - both estimated to achieve a 16% hurdle rate, we believe market adoption of CMNF in the near term is more promising, regardless of specific applications. This study provides state of the art business intelligence information on the conversion economics, risk, and fi nancial analyses for CMNF manufacturing. Thus, the data represents valuable information to entrepreneurs, R&D scientists, and product developers who plan to adopt CMNF in their processes and products. [ABSTRACT FROM AUTHOR]

Curdlan based cryogels were prepared and tested for their structural and thermal properties by using field emission scanning electron microscopy and thermogravimetric analysis, respectively. Volume shrinkage, mechanical performance, swelling, solubility and density were accessed as a function of composition, which included cellulose nanofibrils (CNF) and polyethylene oxide (PEO). PEO/CURD and PEO/CURD/CNF cryogels exhibited porous and layered structures. The addition of CNF significantly improved the in-vitro release of a nonsteroidal anti-inflammatory drug (diclofenac sodium), which is a promising alternative to current non-biodegradable systems. [ABSTRACT FROM AUTHOR]

The application potential of cellulose nanofibril (CNF) aerogels has been hindered by the slow and costly freeze- or supercritical drying methods. Here, CNF aerogel membranes with attractive mechanical, optical, and gas transport properties are prepared in ambient conditions with a facile and scalable process. Aqueous CNF dispersions are vacuum-filtered and solvent exchanged to 2-propanol and further to octane, followed by ambient drying. The resulting CNF aerogel membranes are characterized by high transparency (>90% transmittance), stiffness (6 GPa Young's modulus, 10 GPa cm3 g−1 specific modulus), strength (97 MPa tensile strength, 161 MPa m3 kg−1 specific strength), mesoporosity (pore diameter 10-30 nm, 208 m2 g−1 specific surface area), and low density (≈0.6 g cm−3). They are gas permeable thus enabling collection of nanoparticles (for example, single-walled carbon nanotubes, SWNT) from aerosols under pressure gradients. The membranes with deposited SWNT can be further compacted to transparent, conductive, and flexible conducting films (90% specular transmittance at 550 nm and 300 Ω ◻ −1 sheet resistance with AuCl3-salt doping). Overall, the developed aerogel membranes pave way toward use in gas filtration and transparent, flexible devices. [ABSTRACT FROM AUTHOR]

The elevated levels of tree mortality attributed to mountain pine beetle (MPB) (Dendroctonus ponderosoe Hopkins) in western North American forests create forest management challenges. This investigation introduces the production of submicron or nanometer lignocellulose fibrils for value-added materials from the widely available resource represented by dead pines after an outbreak. Lodgepole pine (Pinus contort Dougl. ex Loud.), trees from two different times since infestation and a noninfested live tree as a control were used for mechanical fibrillation. Fiber deconstruction down to the micro-/nanoscale from infested wood was performed using mechanical fibrillation, without any chemical (pre)treatment. The effects of fibrillation were monitored as a function of processing time, and the respective products were characterized. The changes in fibril morphology, cellulose crystallinity, water retention value, and cellulase adsorption capacity were determined. Interestingly, no significant differences were found between fibrillated samples from the live and the MPB-killed trees. It can be concluded that MPB-killed lodgepole pine is a suitable feedstock for the production of lignocellulose micro-/nanofibrils. [ABSTRACT FROM AUTHOR]

Chitosan (CS), cellulose nanofibrils (CNF) and boric acid, the latter of which was used as flame retardant, were combined in transparent, hybrid films that were produced by solvent casting. The flammability and the thermal stability of the films were studied with respect to the loading of the inorganic component. Chitosan films displayed fire retardancy properties, which were enhanced in the presence of boric acid. CNF films, in contrast to those from chitosan, were readily flammable; however, when combined with boric acid (30 w%), they became self-extinguishing. Most remarkably, bicomponent films comprising CNF and chitosan, displayed better fire retardancy than that of neat CS films. Moreover, boric acid improved the thermal stability of the bicomponent films. The tensile strength and Young’s modulus of CS, CNF and CS-CNF films improved at intermediate boric acid addition, although a negative effect on elongation was observed. [ABSTRACT FROM AUTHOR]

Cellulose-based humidity sensors have attracted great research interest due to their hydrophilicity, biodegradability, and low cost. However, they still suffer from relatively low humidity sensitivity. Due to the presence of negatively charged carboxylate groups, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibril (CNF) exhibits enhanced hydrophilicity and ion conductivity, which is considered a promising candidate for humidity sensing. In this work, we developed a facile strategy to improve the humidity sensitivity of CNF films by regulating their surface charge density. With the increase in surface charge density, both water uptake and charge carrier densities of the CNF films can be improved, enabling a humidity sensitivity of up to 44.5 % (%RH)−1, higher than that of most polymer-based humidity sensors reported in the literature. Meanwhile, the sensor also showed good linearity (R2 = 0.998) over the 15–75 % RH at 1 kHz. With these features, the CNF film was further demonstrated for applications in noncontact sensing, such as human respiration, moisture on fingertips, and water leakage, indicating the great potential of CNF film in humidity monitoring. A simple strategy for enhancing the humidity sensing performance of TEMPO-oxidized CNF film is proposed through the surface charge density modulation. The high surface charge density (1.45 mmol g−1) of CNF endows the sensor with increased water uptake and charge carrier densities, thus leading to improved humidity sensing performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Producing hydrogels capable of mimicking the biomechanics of soft tissue remains a challenge. We explore the potential of plant-based hydrogels as polysaccharide tragacanth gum and antioxidant lignin nanoparticles in bioactive multicomponent hydrogels for tissue engineering. These natural components are combined with TEMPO-oxidized cellulose nanofibrils, a material with known shear thinning behavior. Hydrogels presented tragacanth gum (TG) concentration-dependent rheological properties suitable for extrusion 3D printing. TG enhanced the swelling capacity up to 645% and the degradation rate up to 1.3%/day for hydrogels containing 75% of TG. Young's moduli of the hydrogels varied from 5.0 to 11.6 kPa and were comparable to soft tissues like skin and muscle. In vitro cell viability assays revealed that the scaffolds were non-toxic and promoted proliferation of hepatocellular carcinoma HepG2 cells. Therefore, the plant-based hydrogels designed in this work have a significant potential for tissue engineering. [Display omitted] • 3D printed hydrogels made of cellulose nanofibrils, lignin nanoparticles, and tragacanth gum were developed and characterized • Tragacanth gum enhanced rheological properties, swelling ratio, and degradation rate • Hydrogels presented no toxicity and promoted proliferation of HepG2 cells • Potential application of plant-based materials in tissue engineering [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNF) were incorporated in water-in-oil (W/O) microemulsions and emulsions, as well as water-in-oil-in-water (W/O/W) multiple emulsions using soybean oil. The addition of CNF to the aqueous phase expanded the composition range to obtain W/O/W emulsions. CNF also increased the viscosity of the continuous phase and reduced the drop size both of which increased the stability and effective viscosity of the emulsions. The effects of oil type and polarity on the properties of the W/O/W emulsions were tested with limonene and octane, which compared to soybean oil produced a smaller emulsion drop size, and thus a higher emulsion viscosity. Overall, CNF are a feasible alternative to conventional polysaccharides as stability enhancers for normal and multiple emulsions that exhibit strong shear thinning behavior. [ABSTRACT FROM AUTHOR]

Plant-based hydrogels have attracted great attention in biomedical fields since they are biocompatible and based on natural, sustainable, cost-effective, and widely accessible sources. Here, we introduced new viscoelastic bio-inks composed of quince seed mucilage and cellulose nanofibrils (QSM/CNF) easily extruded into 3D lattice structures through direct ink writing in ambient conditions. The QSM/CNF inks enabled precise control on printing fidelity where CNF endowed objects with shape stability after freeze-drying and with suitable porosity, water uptake capacity, and mechanical strength. The compressive and elastic moduli of samples produced at the highest CNF content were both increased by ~100% (from 5.1 ± 0.2 kPa and 32 ± 1 kPa to 10.7 ± 0.5 and 64 ± 2 kPa, respectively). These values ideally matched those reported for soft tissues; accordingly, the cell compatibility of the printed samples was evaluated against HepG2 cells (human liver cancer). The results confirmed the 3D hydrogels as being non-cytotoxic and suitable to support attachment, survival, and proliferation of the cells. All in all, the newly developed inks allowed sustainable 3D bio-hydrogels fitting the requirements as scaffolds for soft tissue engineering. [ABSTRACT FROM AUTHOR]

Motivated by the quest for biocompatibility, we report on oil-in-water (O/W), high-internal-phase Pickering emulsions stabilized via complexes of mechanical cellulose nanofibrils (CNF) and food-grade cationic surfactant ethyl lauroyl arginate (LAE). The complexation of oppositely charged CNF and LAE can be held together by electrostatic interaction. Their effect on suspensions electrostatic stabilization, heteroaggregation state, and emulsifying ability was studied and related to properties of resultant interfacial tension between oil and water and 3D printing of emulsions. The Pickering system with adjustable droplet diameter and stability against creaming and oiling-off during storage was achieved resting with LAE loading. Complexes formed by LAE adjustment act as Pickering stabilizers and three-dimensional networks in emulsion system, forming a scaffold with elastoplastic rheological properties that flows above critical stress while, without any additional treatment, exhibiting the required self-standing properties for 3D printing. By understanding the properties of CNF/LAE behavior in bulk and on interfaces, printing edible functional foods of CNF/LAE-based emulgel inks has been demonstrated to enable regulation of oil release. [Display omitted] [ABSTRACT FROM AUTHOR]

• Biomaterials are developed from lightweight and strong nanocellulose gels and foams. • Nanocellulose scaffolds (NCS) are promising analogues to extracellular matrices. • Their biology and structure make plant nanomaterials ideal for tissue engineering. • Cell culturing and implantation with NCS are demonstrated in vitro and in vivo. • Next-generation biomaterials can be engineered from nanocelluloses. We report on the latest scientific advances related to the use of porous foams and gels prepared with cellulose nanofibrils (CNF) and nanocrystals (CNC) as well as bacterial nanocellulose (BNC) – collectively nanocelluloses – as biomedical materials for application in tissue regeneration. Interest in such applications stems from the lightweight and strong structures that can be efficiently produced from these nanocelluloses. Dried nanocellulose foams and gels, including xerogels, cryogels, and aerogels have been synthesized effortlessly using green, scalable, and cost-effective techniques. Methods to control structural features (e.g., porosity, morphology, and mechanical performance) and biological interactions (e.g., biocompatibility and biodegradability) are discussed in light of specific tissues of interest. The state-of-the-art in the field of nanocellulose-based scaffolds for tissue engineering is presented, covering physicochemical and biological properties relevant to these porous systems that promise groundbreaking advances. Specifically, these materials show excellent performance for in vitro cell culturing and in vivo implantation. We report on recent efforts related to BNC scaffolds used in animal and human implants, which furthermore support the viability of CNF- and CNC-based scaffolds in next-generation biomedical materials. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials (CNs) are promising green materials due to their unique properties as well as their environmental benefits. Among these materials, cellulose nanofibrils (CNFs) and nanocrystals (CNCs) are the most extensively researched types of CNs. While they share some fundamental properties like low density, biodegradability, biocompatibility, and low toxicity, they also possess unique differentiating characteristics such as morphology, rheology, aspect ratio, crystallinity, mechanical and optical properties. Therefore, numerous comparative studies have been conducted, and recently, various studies have reported the synergetic advantages resulting from combining CNF and CNC. In this review, we initiate by addressing the terminology used to describe combinations of these and other types of CNs, proposing "hybrid cellulose nanomaterials" (HCNs) as the standardized classifictation for these materials. Subsequently, we briefly cover aspects of properties-driven applications and the performance of CNs, from both an individual and comparative perspective. Next, we comprehensively examine the potential of HCN-based materials, highlighting their performance for various applications. In conclusion, HCNs have demonstraded remarkable success in diverse areas, such as food packaging, electronic devices, 3D printing, biomedical and other fields, resulting in materials with superior performance when compared to neat CNF or CNC. Therefore, HCNs exhibit great potential for the development of environmentally friendly materials with enhanced properties. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Polarized light imaging of CNF flow. • Extensional rheology of CNF hydrogels and guar gum and cellulose acetate solutions. • Relationship of biopolymer rheology and spinnability. • Continuous wet-spinning of CNF in a with an assisting biopolymer carrier. Abstract The shear and extensional rheology of aqueous suspensions of cellulose nanofibrils (CNF) were investigated under dynamic and steady flow fields. The results were compared to those for two biopolymer solutions, cellulose acetate, CA, and guar gum, GG. Wet-spinning experiments were conducted for each system and the outcome related to the respective rheological profile. The spinnability of the system correlated with strong Newtonian and viscous responses under shear as well as long breakup time in capillary breakup experiments. CA solution was the most spinnable, also displaying the strongest Newtonian liquid behavior and the longest capillary breakup time. In contrast, the most shear-thinning and elastic CNF suspension showed instant capillary breakup and was considerably less spinnable. This is due to the limited entanglement between the rigid cellulose fibrils. In order to enable continuous wet-spinning of CNF without filament breakup, GG and CA were used as carrier components in coaxial spinning. The shear and extensional rheology of the system is discussed considering both as supporting polymers. [ABSTRACT FROM AUTHOR]

Enzymatic processing is considered a promising approach for advancing environmentally friendly industrial processes, such as the use of endoglucanase (EG) enzyme in the production of nanocellulose. However, there is ongoing debate regarding the specific properties that make EG pretreatment effective in isolating fibrillated cellulose. To address this issue, we investigated EGs from four glycosyl hydrolase (GH) families (5, 6, 7, and 12) and examined the roles of the three-dimensional structure and catalytic features, with a focus on the presence of a carbohydrate binding module (CBM). Using eucalyptus Kraft wood fibers, we produced cellulose nanofibrils (CNFs) through mild enzymatic pretreatment, followed by disc ultra-refining. Comparing the results with the control (without pretreatment), we observed that GH5 and GH12 enzymes (without CBM) reduced fibrillation energy by approximately 15 %. The most significant energy reduction, 25 and 32 %, was achieved with GH5 and GH6 linked to CBM, respectively. Notably, these CBM-linked EGs improved the rheological properties of CNF suspensions without releasing soluble products. In contrast, GH7-CBM exhibited significant hydrolytic activity, resulting in the release of soluble products, but did not contribute to a reduction in fibrillation energy. This discrepancy can be attributed to the large molecular weight and wide cleft of GH7-CBM, which led to the release of soluble sugars but had little impact on fibrillation. Our findings suggest that the improved fibrillation observed with EG pretreatment is primarily driven by efficient enzyme adsorption on the substrate and modification of the surface viscoelasticity (amorphogenesis), rather than hydrolytic activity or release of products. Energy consumption and properties of cellulose nanofibers produced after single-step, low-loading enzyme pretreatment of wood pulp. [Display omitted] [ABSTRACT FROM AUTHOR]

Having competitive compressive strength and resilience as well as biocompatibility simultaneously still remains a challenge for composite hydrogels, which is critical if they are aimed for use as functional biomaterials. In the present work, a facile and green method was designed for producing a composite hydrogel based on polyvinyl alcohol (PVA) and xylan with sodium tri-metaphosphate (STMP) as cross-linker, aiming to specially enhance its compressive properties with the aid of eco-friendly produced formic acid esterified cellulose nanofibrils (CNFs). The CNF addition caused a compressive strength decrease of the hydrogels, although the values (2.34–4.57 MPa at a compressive strain of 70 %) were still at a high level among the reported PVA (or polysaccharide) based hydrogels so far. However, the compressive resilience of the hydrogels was enhanced significantly by the CNF addition, with maximal compressive strength retention of 88.49 % and 99.67 % in height recovery after 1000 compression cycles at a strain of 30 %, which reflects the significant influence of CNFs on the compressive recovery ability of the hydrogel. All materials used in the present work are naturally non-toxic with good biocompatible, which makes the synthesized hydrogels with great potential in biomedical applications, e.g., soft-tissue engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

In this review we introduce recent advances in the development of cellulose nanomaterials and the construction of high order structures by applying some principles of colloid and interface science. These efforts take advantage of natural assemblies in the form of fibers that nature constructs by a biogenetic bottom-up process that results in hierarchical systems encompassing a wide range of characteristic sizes. Following the reverse process, a top-down deconstruction, cellulose materials can be cleaved from fiber cell walls. The resulting nanocelluloses, mainly cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC, i.e., defect-free, rod-like crystalline residues after acid hydrolysis of fibers), have been the subject of recent interest. This originates from the appealing intrinsic properties of nanocelluloses: nanoscale dimensions, high surface area, morphology, low density, chirality and thermo-mechanical performance. Directing their assembly into multiphase structures is a quest that can yield useful outcomes in many revolutionary applications. As such, we discuss the use of non-specific forces to create thin films of nanocellulose at the air–solid interface for applications in nano-coatings, sensors, etc. Assemblies at the liquid–liquid and air–liquid interfaces will be highlighted as means to produce Pickering emulsions, foams and aerogels. Finally, the prospects of a wide range of hybrid materials and other systems that can be manufactured via self and directed assembly will be introduced in light of the unique properties of nanocelluloses. [ABSTRACT FROM AUTHOR]

In this review, we discuss the application of cellulose nanoparticles as a sustainable and cost-effective source of green stabilizers for formulation of foodstuff. Fibrillar cellulose nanocrystal and nanofibril stabilize Pickering systems because of their ability to adsorb at the oil/water interfaces, forming protective layers. They also form associative structures in the continuous phase, increasing their viscoelastic properties and preventing flocculation. We describe the chemical and structural features of nanocelluloses and discuss the principles that support their utilization as stabilizers, especially in the context of recent prospects in food and health domains, given safety and regulatory advances. In addition, we describe the benefits of combining nanocelluloses with other food ingredients to extend their functional attributes. Particularly, nanocellulose-based Pickering emulsions are used to create edible soft materials with multiple functionalities. This article is expected to stimulate the use of nanocelluloses as functional ingredients to create food products with improved performance and novel properties. [Display omitted] • Plant-based nanocellulosic particles are sustainable and economic natural nanoparticles. • Cellulose nanocrystals and nanofibrils are effective stabilizers in Pickering emulsions. • Novel food emulsions are being created from cellulose nanoparticles and composites. • Nanocellulose-stabilized emulsions provide new or improved functionalities in foods. [ABSTRACT FROM AUTHOR]

We proposed a simple method to process hydrogels containing polyvinyl alcohol and cellulose nanofibrils (PVA/CNF) to prepare volumetric architectures by direct ink writing (DIW). The presence of CNF in the aqueous PVA suspensions conferred rheology profiles that were suitable for extrusion and solidification in pre-designed shapes. The viscoelastic behavior of the hybrid inks enabled precise control on processability and shape retention, for instance, as demonstrated in multilayered lattice structures of high fidelity. After lyophilization, the obtained 3D-printed hydrogels presented a very high porosity, with open and interconnected pores, allowing a high-water uptake capacity (up to 1600%). The mechanical strength of the composite 3D-printed materials matched those of soft tissues, opening opportunities for skin applications. As such, drug-loaded samples revealed a controlled and efficient delivery of an antioxidant (ascorbic acid) in PBS buffer media at 23 °C (~80% for 8 h). Altogether, PVA/CNF hydrogels were introduced as suitable precursors of 3D-lattice geometries with excellent physical and mechanical characteristics. [Display omitted] • Polyvinyl alcohol/cellulose nanofibrils hydrogels possessed excellent viscoelastic properties suitable for printing. • Direct ink writing was used to print 3D lattice structures employing PVA/ cellulose nanofibrils hydrogels. • Five layers were printed with high fidelity and fair resolution without any deformation after printing. • Lyophilized 3D-printed samples revealed high porosity and water uptake capacity. • All samples had significant mechanical performances similar to soft tissues. [ABSTRACT FROM AUTHOR]

Direct-ink-writing (DIW) of hydrogels has become an attractive research area due to its capability to fabricate intricate, complex, and highly customizable structures at ambient conditions for various applications, including biomedical purposes. In the current study, cellulose nanofibrils reinforced aloe vera bio-hydrogels were utilized to develop 3D geometries through the DIW technique. The hydrogels revealed excellent viscoelastic properties enabled extruding thin filaments through a nozzle with a diameter of 630 μm. Accordingly, the lattice structures were printed precisely with a suitable resolution. The 3D-printed structures demonstrated significant wet stability due to the high aspect ratio of the nano- and microfibrils cellulose, reinforced the hydrogels, and protected the shape from extensive shrinkage upon drying. Furthermore, all printed samples had a porosity higher than 80% and a high-water uptake capacity of up to 46 g/g. Altogether, these fully bio-based, porous, and wet stable 3D structures might have an opportunity in biomedical fields. [Display omitted] • Development of a bio-hydrogel composed of aloe vera and cellulose nanofibrils • Excellent viscoelastic properties suitable for direct ink writing • Precisely 3D printing of lattice geometry with a suitable resolution • Good mechanical performances and high porosity and water uptake capacity [ABSTRACT FROM AUTHOR]

• Hydrogels are synthesized as double networks with PAM/CNF/LiCl. • LiCl in the hydrogel provides freezing and dehydration tolerance. • The interactions between CNF and LiCl allow stretchability and conductivity. • The hydrogel is used in the development of reliable flexible supercapacitors. Ionically-conductive and stretchable hydrogels are ideally suited for the synthesis of flexible electronic devices. However, conventional hydrogels undergo dehydration at ambient conditions and freeze at subzero temperatures, limiting their functions. As an alternative to counteract these limitations, we propose double network hydrogels that are easily synthesized by a one-step acrylamide (AM) polymerization in the presence of cellulose nanofibrils (CNF) and LiCl. Following molecular dynamics simulation, thermogravimetric and spectroscopic (Raman and low-field nuclear magnetic resonance) analyses, we show that LiCl increases the interactions between the colloidal phase and water molecules, ensuring water holding capability at atmospheric conditions and endowing the hydrogels with freezing tolerance over a wide range of temperatures, from −80 to 25 °C. The synergy between CNF and LiCl is critical in maintaining the mechanical strength of the system, which simultaneously displays high stretchability (~748%) and ionic conductivity (2.25 S/m) at low temperatures (−40 °C). As a proof of concept, a flexible supercapacitor comprising the proposed electrolyte hydrogel is demonstrated as a reliable, low-temperature electrochemical device. Our results provide the basis for simple and universally applicable systems that fulfill the requirements of flexible electronics under extreme cold conditions. [ABSTRACT FROM AUTHOR]