Properties and environmental sustainability of fungal chitin nanofibril reinforced cellulose acetate films and nanofiber mats by solution blow spinning.

Materials from biological origin composed by renewable carbon facilitate the transition from linear carbon-intensive economy to a sustainable circular economy. Accordingly, we use solution blow spinning to develop fully biobased cellulose acetate films and nanofiber mats reinforced with fungal chitin nanofibrils (ChNFs), an emerging bio-colloid with lower carbon footprint compared to crustacean-derived nanochitin. This study incorporates fungal ChNFs into spinning processes for the first time. ChNF addition reduces film surface roughness, modifies film water affinity, and tailors the nanofiber diameter of the mats. The covalently bonded ß-D-glucans of ChNFs act as a binder to improve the interfacial properties and consequently load transference to enhance the mechanical properties. Accordingly, the Young's modulus of the films increases from 200 ± 18 MPa to 359 ± 99 MPa with 1.5 wt% ChNFs, while the elongation at break increases by ~45 %. Life cycle assessment (LCA) is applied to quantify the environmental impacts of solution blow spinning for the first time, providing global warming potential values of 69.7-347.4 kg·CO2-equiv.·kg-1. Additionally, this work highlights the suitability of ChNFs as reinforcing fillers during spinning and proves the reinforcing effect of mushroom-derived chitin in bio-based films, opening alternatives for sustainable materials development beyond nanocelluloses in the near future.

Cytotoxicity and Inflammatory Effects of Chitin Nanofibrils Isolated from Fungi.

Fungal nanochitin can assist the transition from the linear fossil-based economy to a circular biobased economy given its environmental benefits over conventional crustacean-nanochitin. Its real-world implementation requires carefully assessing its toxicity so that unwanted human health and environmental issues are avoided. Accordingly, the cytotoxicity and inflammatory effects of chitin nanofibrils (ChNFs) from white mushroom is assessed. ChNFs are few nanometers in diameter, with a 75.8% N-acetylation degree, a crystallinity of 59.1%, and present a 44:56 chitin/glucan weight ratio. Studies are conducted for aqueous colloidal ChNF dispersions (0-5 mg·mL-1) and free-standing films having physically entangled ChNFs. Aqueous dispersions of chitin nanocrystals (ChNCs) isolated via hydrochloric acid hydrolysis of α-chitin powder are also evaluated for comparison. Cytotoxicity studies conducted in human fibroblasts (MRC-5 cells) and murine brain microglia (BV-2 cells) reveal a comparatively safer behavior over related biobased nanomaterials. However, a strong inflammatory response was observed when BV-2 cells were cultured in the presence of colloidal ChNFs. These novel cytotoxicity and inflammatory studies shed light on the potential of fungal ChNFs for biomedical applications.

Chitin Nanofibrils from Fungi for Hierarchical Gel Polymer Electrolytes for Transient Zinc-Ion Batteries with Stable Zn Electrodeposition.

Rechargeable batteries play an integral role toward carbon neutrality. Environmentally sustainable batteries should consider the trade-offs between material renewability, processability, thermo-mechanical and electrochemical performance, as well as transiency. To address this dilemma, we follow circular economy principles to fabricate fungal chitin nanofibril (ChNF) gel polymer electrolytes (GPEs) for zinc-ion batteries. These biocolloids are physically entangled into hierarchical hydrogels with specific surface areas of 49.5 m2 ·g-1 . Ionic conductivities of 54.1 mS·cm-1 and a Zn2+ transference number of 0.468 are reached, outperforming conventional non-renewable/non-biodegradable glass microfibre separator-liquid electrolyte pairs. Enabled by its mechanically elastic properties and large water uptake, a stable Zn electrodeposition in symmetric Zn|Zn configuration with a lifespan above 600 h at 9.5 mA·cm-2 is obtained. At 100 mA·g-1 , the discharge capacity of Zn/α-MnO2 full cells increases above 500 cycles when replacing glass microfiber separators with ChNF GPEs, while the rate performance remains comparable to glass microfiber separators. To make the battery completely transient, the metallic current collectors are replaced by biodegradable polyester/carbon black composites undergoing degradation in water at 70 °C. This work demonstrates the applicability of bio-based materials to fabricate green and electrochemically competitive batteries with potential applications in sustainable portable electronics, or biomedicine.

Cellulose-Based Ionic Conductor: An Emerging Material toward Sustainable Devices.

Ionic conductors (ICs) find widespread applications across different fields, such as smart electronic, ionotronic, sensor, biomedical, and energy harvesting/storage devices, and largely determine the function and performance of these devices. In the pursuit of developing ICs required for better performing and sustainable devices, cellulose appears as an attractive and promising building block due to its high abundance, renewability, striking mechanical strength, and other functional features. In this review, we provide a comprehensive summary regarding ICs fabricated from cellulose and cellulose-derived materials in terms of fundamental structural features of cellulose, the materials design and fabrication techniques for engineering, main properties and characterization, and diverse applications. Next, the potential of cellulose-based ICs to relieve the increasing concern about electronic waste within the frame of circularity and environmental sustainability and the future directions to be explored for advancing this field are discussed. Overall, we hope this review can provide a comprehensive summary and unique perspectives on the design and application of advanced cellulose-based ICs and thereby encourage the utilization of cellulosic materials toward sustainable devices.

Designing antimicrobial biomembranes via clustering amino-modified cellulose nanocrystals on silk fibroin ß-sheets.

The continuous rising of infections caused by multidrug-resistant pathogens is becoming a global healthcare concern. Developing new bio-based materials with unique chemical and structural features that allow efficient interaction with bacteria is thus important for fighting this phenomenon. To address this issue, we report an antimicrobial biomaterial that results from clustering local facial amphiphilicity from amino-modified cellulose on silk fibroin ß-sheets, by simply blending the two components through casting technology. A simple but effective method for creating a membrane that is antibacterial and non-cytotoxic. Amino-modified cellulose nanocrystals (CNC-NH2) were mixed with proteinaceous silk fibroin (SF) which resulted in a material with improved crystallinity, higher ß-sheet content, and exposed amino-groups at its surface features, proven by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS), that does not occur when the components are individually assembled. The resulting material possesses important antibacterial activity inducing >3 CFU log10 reduction of Escherichia coli and Staphylococcus epidermidis, while the pristine membranes show no antibacterial effect. The chemical interactions occurring between SF and CNC-NH2 during casting, exposing the amino moieties at the surface of the material, are proposed as the main reason for this antimicrobial activity. Importantly, the membranes are non-cytotoxic, showing their potential to be used as a new bioinspired material with intrinsic antibacterial activity for biomedical applications. Those may include coatings for medical devices for the control of healthcare-associated infections, with no need for including external antimicrobial agents in the material.

Multi-Responsive Supercapacitors from Chiral Nematic Cellulose Nanocrystal-Based Activated Carbon Aerogels.

The development of long-lived electrochemical energy storage systems based on renewable materials is integral for the transition toward a more sustainable society. Supercapacitors have garnered considerable interest given their impressive cycling performance, low cost, and safety. Here, the first example of a chiral nematic activated carbon aerogel is shown. Specifically, supercapacitor materials are developed based on cellulose, a non-toxic and biodegradable material. The chiral nematic structure of cellulose nanocrystals (CNCs) is harnessed to obtain free-standing hierarchically ordered activated carbon aerogels. To impart multifunctionality, iron- and cobalt-oxide nanoparticles are incorporated within the CNC matrix. The hierarchical structure remains intact even at nanoparticle concentrations of ≈70 wt%. The aerogels are highly porous, with specific surface areas up to 820 m2 g-1 . A maximum magnetization of 17.8 ± 0.1 emu g-1 with superparamagnetic behavior is obtained, providing a base for actuator applications. These materials are employed as symmetric supercapacitors; owing to the concomitant effect of the hierarchically arranged carbon skeleton and KOH activation, a maximum Cp of 294 F g-1 with a capacitance retention of 93% after 2500 cycles at 50 mV s-1 is achieved. The multifunctionality of the composite aerogels opens new possibilities for the use of biomass-derived materials in energy storage and sensing applications.

Bottom-Up Design of a Green and Transient Zinc-Ion Battery with Ultralong Lifespan.

Transient batteries are expected to lessen the inherent environmental impact of traditional batteries that rely on toxic and critical raw materials. This work presents the bottom-up design of a fully transient Zn-ion battery (ZIB) made of nontoxic and earth-abundant elements, including a novel hydrogel electrolyte prepared by cross-linking agarose and carboxymethyl cellulose. Facilitated by a high ionic conductivity and a high positive zinc-ion species transference number, the optimized hydrogel electrolyte enables stable cycling of the Zn anode with a lifespan extending over 8500 h for 0.25 mA cm-2 - 0.25 mAh cm-2 . On pairing with a biocompatible organic polydopamine-based cathode, the full cell ZIB delivers a capacity of 196 mAh g-1 after 1000 cycles at a current density of 0.5 A g-1 and a capacity of 110 mAh g-1 after 10 000 cycles at a current density of 1 A g-1 . A transient ZIB with a biodegradable agarose casing displays an open circuit voltage of 1.123 V and provides a specific capacity of 157 mAh g-1 after 200 cycles at a current density of 50 mA g-1 . After completing its service life, the battery can disintegrate under composting conditions.

Upcycling discarded cellulosic surgical masks into catalytically active freestanding materials.

ABSTRACT: The COVID-19 pandemic outbreak has resulted in the massive fabrication of disposable surgical masks. As the accumulation of discarded face masks represents a booming threat to the environment, here we propose a solution to reuse and upcycle surgical masks according to one of the cornerstones of the circular economy. Specifically, the non-woven cellulosic layer of the masks is used as an environmentally sustainable and highly porous solid support for the controlled deposition of catalytically active metal-oxide nanoparticles. The native cellulosic fibers from the surgical masks are decorated by titanium dioxide (TiO2), iron oxide (FexOy), and cobalt oxide (CoOx) nanoparticles following a simple and scalable approach. The abundant surface -OH groups of cellulose enable the controlled deposition of metal-oxide nanoparticles that are photocatalytically active or shown enzyme-mimetic activities. Importantly, the hydrophilic highly porous character of the cellulosic non-woven offers higher accessibility of the pollutant to the catalytically active surfaces and high retention in its interior. As a result, good catalytic activities with long-term stability and reusability are achieved. Additionally, developed free-standing hybrids avoid undesired media contamination effects originating from the release of nanoscale particles. The upcycling of discarded cellulosic materials, such as the ones of masks, into high-added-value catalytic materials, results an efficient approach to lessen the waste´s hazards of plastics while enhancing their functionality. Interestingly, this procedure can be extended to the upcycling of other systems (cellulosic or not), opening the path to greener manufacturing approaches of catalytic materials. GRAPHICAL ABSTRACT: A novel approach to upcycle discarded cellulosic surgical masks is proposed, providing a solution to reduce the undesired accumulation of discarded face masks originating from the COVID-19 pandemic. The non-woven cellulosic layer formed by fibers is used as solid support for the controlled deposition of catalytically active titanium dioxide (TiO2), iron oxide (FexOy), and cobalt oxide (CoOx) nanoparticles. Cellulosic porous materials are proven useful for the photocatalytic decomposition of organic dyes, while their peroxidase-like activity opens the door to advanced applications such as electrochemical sensors. The upcycling of cellulose nonwoven fabrics into value-added catalytic materials lessens the waste´s hazards of discarded materials while enhancing their functionality. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10570-022-04441-9.

Hierarchical Nanocellulose-Based Gel Polymer Electrolytes for Stable Na Electrodeposition in Sodium Ion Batteries.

Sodium ion batteries (NIBs) based on earth-abundant materials offer efficient, safe, and environmentally sustainable solutions for a decarbonized society. However, to compete with mature energy storage technologies such as lithium ion batteries, further progress is needed, particularly regarding the energy density and operational lifetime. Considering these aspects as well as a circular economy perspective, the authors use biodegradable cellulose nanoparticles for the preparation of a gel polymer electrolyte that offers a high liquid electrolyte uptake of 2985%, an ionic conductivity of 2.32 mS cm-1 , and a Na+ transference number of 0.637. A balanced ratio of mechanically rigid cellulose nanocrystals and flexible cellulose nanofibers results in a mesoporous hierarchical structure that ensures close contact with metallic Na. This architecture offers stable Na plating/stripping at current densities up to ±500 µA cm-2 , outperforming conventional fossil-based NIBs containing separator-liquid electrolytes. Paired with an environmentally sustainable and economically attractive Na2 Fe2 (SO4 )3 cathode, the battery reaches an energy density of 240 Wh kg-1 , delivering 69.7 mAh g-1 after 50 cycles at a rate of 1C. In comparison, Celgard in liquid electrolyte delivers only 0.6 mAh g-1 at C/4. Such gel polymer electrolytes may open up new opportunities for sustainable energy storage systems beyond lithium ion batteries.

Core-Shell Fe3O4@Au Nanorod-Loaded Gels for Tunable and Anisotropic Magneto- and Photothermia.

Hyperthermia therapeutic treatments require improved multifunctional materials with tunable synergetic properties. Here, we report on the synthesis of Fe3O4@Au core-shell nanorods and their subsequent incorporation into an agarose hydrogel to obtain anisotropic magnetic and optical properties for magneto- and photothermal anisotropic transductions. Highly monodisperse ferrimagnetic Fe3O4 nanorods with tunable size were synthesized using a solvothermal method by varying the amount of hexadecylamine capping ligands. A gold shell was coated onto Fe3O4 nanorods by the intermediate formation of core-satellite structures and a subsequent controlled growth process, leading to an optical response variation from the visible to the near-infrared (NIR) region. The nanorods were oriented within an agarose hydrogel to fabricate free-standing anisotropic materials, providing a proof-of-concept for the applicability of these materials for anisotropic magneto- and photothermia applications. The strong gelling behavior upon cooling and shear-thinning behavior of agarose enable the fabrication of magnetically active continuous hydrogel filaments upon injection. These developed multifunctional nanohybrid materials represent a base for advanced sensing, biomedical, or actuator applications with an anisotropic response.

Multifunctional lignin-based nanocomposites and nanohybrids.

Significant progress in lignins valorization and development of high-performance sustainable materials have been achieved in recent years. Reports related to lignin utilization indicate excellent prospects considering green chemistry, chemical engineering, energy, materials and polymer science, physical chemistry, biochemistry, among others. To fully realize such potential, one of the most promising routes involves lignin uses in nanocomposites and nanohybrid assemblies, where synergistic interactions are highly beneficial. This review first discusses the interfacial assembly of lignins with polysaccharides, proteins and other biopolymers, for instance, in the synthesis of nanocomposites. To give a wide perspective, we consider the subject of hybridization with metal and metal oxide nanoparticles, as well as uses as precursor of carbon materials and the assembly with other biobased nanoparticles, for instance to form nanohybrids. We provide cues to understand the fundamental aspects related to lignins, their self-assembly and supramolecular organization, all of which are critical in nanocomposites and nanohybrids. We highlight the possibilities of lignin in the fields of flame retardancy, food packaging, plant protection, electroactive materials, energy storage and health sciences. The most recent outcomes are evaluated given the importance of lignin extraction, within established and emerging biorefineries. We consider the benefit of lignin compared to synthetic counterparts. Bridging the gap between fundamental and application-driven research, this account offers critical insights as far as the potential of lignin as one of the frontrunners in the uptake of bioeconomy concepts and its application in value-added products.

Degradation Behavior, Biocompatibility, Electrochemical Performance, and Circularity Potential of Transient Batteries.

Transient technology seeks the development of materials, devices, or systems that undergo controlled degradation processes after a stable operation period, leaving behind harmless residues. To enable externally powered fully transient devices operating for longer periods compared to passive devices, transient batteries are needed. Albeit transient batteries are initially intended for biomedical applications, they represent an effective solution to circumvent the current contaminant leakage into the environment. Transient technology enables a more efficient recycling as it enhances material retrieval rates, limiting both human and environmental exposures to the hazardous pollutants present in conventional batteries. Little efforts are focused to catalog and understand the degradation characteristics of transient batteries. As the energy field is a property-driven science, not only electrochemical performance but also their degradation behavior plays a pivotal role in defining the specific end-use applications. The state-of-the-art transient batteries are critically reviewed with special emphasis on the degradation mechanisms, transiency time, and biocompatibility of the released degradation products. The potential of transient batteries to change the current paradigm that considers batteries as harmful waste is highlighted. Overall, transient batteries are ready for takeoff and hold a promising future to be a frontrunner in the uptake of circular economy concepts.

Stable Na Electrodeposition Enabled by Agarose-Based Water-Soluble Sodium Ion Battery Separators.

Developing efficient energy storage technologies is at the core of current strategies toward a decarbonized society. Energy storage systems based on renewable, nontoxic, and degradable materials represent a circular economy approach to address the environmental pollution issues associated with conventional batteries, that is, resource depletion and inadequate disposal. Here we tap into that prospect using a marine biopolymer together with a water-soluble polymer to develop sodium ion battery (NIB) separators. Mesoporous membranes comprising agarose, an algae-derived polysaccharide, and poly(vinyl alcohol) are synthesized via nonsolvent-induced phase separation. Obtained membranes outperform conventional nondegradable NIB separators in terms of thermal stability, electrolyte wettability, and Na+ conductivity. Thanks to the good interfacial adhesion with metallic Na promoted by the hydroxyl and ether functional groups of agarose, the separators enable a stable and homogeneous Na deposition with limited dendrite growth. As a result, membranes can operate at 200 µA cm-2, in contrast with Celgard and glass microfiber, which short circuit at 50 and 100 µA cm-2, respectively. When evaluated in Na3V2(PO4)3/Na half-cells, agarose-based separators deliver 108 mA h g-1 after 50 cycles at C/10, together with a remarkable rate capability. This work opens up new possibilities for the use of water-degradable separators, reducing the environmental burdens arising from the uncontrolled accumulation of electronic waste in marine or land environments.

Influence of cellulose nanocrystal surface functionalization on the bending response of cellulose nanocrystal/ionic liquid soft actuators.

This work reports the development of renewable cellulose nanocrystal (CNC) and ionic liquid (IL) hybrid materials for bending actuator applications. For this purpose, cellulose nanocrystals with different surface charges (neutral, positive and negative) were prepared and increasing amounts of the IL 2-hydroxy-ethyl-trimethylammonium dihydrogen phosphate ([Ch][DHP]) (10 and 25 wt%) were incorporated into the CNC hosting matrix. The morphology of the samples was evaluated, proving that both surface charge and IL incorporation do not affect the characteristic layered structure of the CNC. Atomic force microscopy results reveal a sea-island morphology in the hybrid films, where CNC bundles are surrounded by [Ch][DHP]-rich regions. An increase in the electrical conductivity is observed upon IL incorporation into the CNC matrix, regardless of the CNC surface charge. The highest electrical conductivity values are observed for IL/CNC (+) 25 wt% with an electrical conductivity of 3.18 × 10-5± 2.75 × 10-7 S cm-1 and IL/CNC (-) 10 wt% (1.26 × 10-5± 5.92 × 10-6 S cm-1). The highest bending displacement of 2.1 mm for an applied voltage of 4.0 Vpp at a frequency of 100 mHz was obtained for the IL/CNC (+) 25 wt% composite, demonstrating the suitability of cellulose to develop soft actuators.

Comparative life cycle assessment of high performance lithium-sulfur battery cathodes.

Lithium-sulfur (Li-S) batteries present a great potential to displace current energy storage chemistries thanks to their energy density that goes far beyond conventional batteries. To promote the development of greener Li-S batteries, closing the existing gap between the quantification of the potential environmental impacts associated with Li-S cathodes and their performance is required. Herein we show a comparative analysis of the life cycle environmental impacts of five Li-S battery cathodes with high sulfur loadings (1.5-15 mg·cm-2) through life cycle assessment (LCA) methodology and cradle-to-gate boundary. Depending on the selected battery, the environmental impact can be reduced by a factor up to 5. LCA results from Li-S batteries are compared with the conventional lithium ion battery from Ecoinvent 3.6 database, showing a decreased environmental impact per kWh of storage capacity. A predominant role of the electrolyte on the environmental burdens associated with the use of Li-S batteries was also found. Sensitivity analysis shows that the specific impacts can be reduced by up to 70% by limiting the amount of used electrolyte. Overall, this manuscript emphasizes the potential of Li-S technology to develop environmentally benign batteries aimed at replacing existing energy storage systems.

A Sodium-Ion Battery Separator with Reversible Voltage Response Based on Water-Soluble Cellulose Derivatives.

The development of efficient, safe, and environmentally friendly energy storage systems plays a pivotal role in moving toward a more sustainable society. Sodium-ion batteries (NIBs) have garnered considerable interest in grid energy storage applications because of the abundance of sodium, low cost, and suitable redox potential. However, NIB technology is still in its infancy, especially with regard to separators. Here we develop a novel separator based on renewable water-soluble cellulose derivatives. Carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) are cross-linked to afford large-specific-surface-area membranes upon nonsolvent-induced phase separation (NIPS). Long-term galvanostatic cycling in a symmetric Na/Na cell configuration shows an impressive reversible voltage response with a square wave shape of the polarization even after 250 h of cycling, indicating remarkably stable Na plating and stripping with Na dendrite growth suppression. This novel membrane is evaluated as a separator in Na3V2(PO4)3/Na half-cells. After 10 cycles at C/10, the cellulosic separator delivers a capacity of 74 mA·h·g-1 with a 100% Coulombic efficiency compared to that of 61 mA·h·g-1 and 96% obtained for Whatman GF/D as a commercially available separator. Our work provides novel cues for the development of biomass-derived porous membranes to function as battery separators, surpassing the performance of commercially available separators based on fossil resources in terms of capacity retention, Coulombic efficiency, homogeneous plating/stripping of Na, and dendrite growth suppression. These separators, which may be extended to other battery systems, are expected to play a significant role in developing sustainable energy storage systems.

Cellulose Nanocrystal and Water-Soluble Cellulose Derivative Based Electromechanical Bending Actuators.

This study reports a versatile method for the development of cellulose nanocrystals (CNCs) and water-soluble cellulose derivatives (methyl cellulose (MC), hydroxypropyl cellulose (HPC), and sodium carboxymethyl cellulose (NaCMC)) films comprising the ionic liquid (IL) 2-hydroxy-ethyl-trimethylammonium dihydrogen phosphate ([Ch][DHP]) for actuator fabrication. The influence of the IL content on the morphology and physico-chemical properties of free-standing composite films was evaluated. Independently of the cellulose derivative, the ductility of the films increases upon [Ch][DHP] incorporation to yield elongation at break values of nearly 15%. An increase on the electrical conductivity as a result of the IL incorporation into cellulosic matrices is found. The actuator performance of composites was evaluated, NaCMC/[Ch][DHP] showing the maximum displacement along the x-axis of 9 mm at 8 Vpp. Based on the obtained high electromechanical actuation performance, together with their simple processability and renewable nature, the materials fabricated here represent a step forward in the development of sustainable soft actuators of high practical relevance.

Combining cobalt ferrite and graphite with cellulose nanocrystals for magnetically active and electrically conducting mesoporous nanohybrids.

Free-standing mesoporous membranes based on cellulose nanocrystals (CNCs) are fabricated upon the incorporation of cobalt ferrite (CoFe2O4) and graphite nanoparticles at concentrations up to 20 wt % through a soft-templating process. Scanning electron microscopy (SEM) and N2 adsorption-desorption isotherms reveal the development of highly-porous interconnected random 3D structure with surface areas up to 193.9 m2 g-1. Thermogravimetric analysis (TGA) shows an enhanced thermal stability thanks to the formation of a tortuous network limiting the hindrance of degradation by-products. Vibrating sample magnetometer (VSM) reveals a maximum magnetization saturation of 8.77 emu·g-1 with materials having either ferromagnetic or diamagnetic behaviour upon the incorporation of CoFe2O4 and graphite, respectively. Four-point-probe measurements display a maximum electrical conductivity of 9.26 ±â€¯0.04 S·m-1 when graphite is incorporated into CNCs. A proof of concept for the applicability of synthesized nanohybrids for environmental remediation is provided, presenting the advantage of their easy recovery using external magnetic fields.

Water-based 2D printing of magnetically active cellulose derivative nanocomposites.

The fabrication of magnetic materials typically involves expensive, non-scalable, time-consuming or toxic processes. Here we report a scalable, quick and environmentally-benign fabrication of magnetically active materials through screen printing using mechanically flexible paper having micron-sized pores as substrates. In comparison with traditional multicomponent inks, simple aqueous dispersions comprising solely water-soluble cellulose derivatives and cobalt ferrite nanoparticles are used. Depending on the cellulosic matrix used, inks with viscosities in the 500-2.500 mPa s range were obtained for shear rates of 20-100 s-1. Patterns with line widths from 183 to 642 µm with a maximum deviation of 9 % were fabricated. The largest magnetization saturation obtained of 0.024 emu (or 0.021 emu cm-2) for the hydroxypropyl cellulose-based ink demonstrates enough magnetization for applications in areas such as actuators and sensors. This work provides novel insights towards the processing of renewable, magnetically active and mechanically flexible materials with tailored geometries which use water as the sole solvent.

Electroactive γ-Phase, Enhanced Thermal and Mechanical Properties and High Ionic Conductivity Response of Poly (Vinylidene Fluoride)/Cellulose Nanocrystal Hybrid Nanocomposites.

Cellulose nanocrystals (CNCs) were incorporated into poly (vinylidene fluoride) (PVDF) to tailor the mechanical and dielectric properties of this electroactive polymer. PVDF/CNC nanocomposites with concentrations up to 15 wt.% were prepared by solvent-casting followed by quick vacuum drying in order to ensure the formation of the electroactive γ-phase. The changes induced by the presence of CNCs on the morphology of PVDF and its crystalline structure, thermal properties, mechanical performance and dielectric behavior are explored. The results suggest a relevant role of the CNC surface -OH groups, which interact with PVDF fluorine atoms. The real dielectric constant ε' of nanocomposites at 200 Hz was found to increase by 3.6 times up to 47 for the 15 wt.% CNC nanocomposite due to an enhanced ionic conductivity provided by CNCs. The approach reported here in order to boost the formation of the γ-phase of PVDF upon the incorporation of CNCs serves to further develop cellulose-based multifunctional materials.