Local dynamics in molecular solutions of cellulose have been studied using quasi-elastic neutron scattering on ternary mixtures of microcrystalline cellulose, ionic liquid 1-ethyl-3-methyl-imidazolium acetate, and cosolvent dimethylformamide. Two distinct dynamic behaviors in solutions have been identified, with slow dynamics likely attributed to long-range translational diffusion and fast dynamics likely involving the motion of IL in nanoaggregates. The presence of cellulose suppresses both dynamic modes as the residence time for both slow and fast dynamics increases, while the radius of confinement remains invariant upon cellulose dissolution. Arrhenius activation behaviors are followed generally; the activation energy decreases for fast dynamics upon cellulose dissolution while showing no measurable change for slow ones. This study offers new information about the dynamics of an important class of renewable biomaterials.

Maintaining food safety and quality is critical for public health and food security. Conventional food preservation methods, such as pasteurization and dehydration, often change the overall organoleptic quality of the food products. Herein, we demonstrate a method that affects only a thin surface layer of the food, using beef as a model. In this method, Joule heating is generated by applying high electric power to a carbon substrate in <1 s, which causes a transient increase of the substrate temperature to > ~2000 K. The beef surface in direct contact with the heating substrate is subjected to ultra-high temperature flash heating, leading to the formation of a microbe-inactivated, dehydrated layer of ~100 µm in thickness. Aerobic mesophilic bacteria, Enterobacteriaceae, yeast and mold on the treated samples are inactivated to a level below the detection limit and remained low during room temperature storage of 5 days. Meanwhile, the product quality, including visual appearance, texture, and nutrient level of the beef, remains mostly unchanged. In contrast, microorganisms grow rapidly on the untreated control samples, along with a rapid deterioration of the meat quality. This method might serve as a promising preservation technology for securing food safety and quality.

The presence of pesticide and herbicide residues on fruits and vegetables poses significant health risks, making it a major concern for consumers worldwide. We engineered Cu 2+-chelated chitosan nanocrystal (Cu 2+-ChNC), a 1D porous material, from nanocrystals of chitin, derived from fishery waste, such as shrimp and crab shells. These nanocrystals are scaffolded by Cu 2+ ions, forming a unique nanochannel structure with a diameter of about 1.5 nm. Our Cu 2+- ChNCs have shown exceptional efficiency in absorbing common chemical residues, such as glyphosate and chlorpyrifos. Additionally, applying an aqueous Cu 2+-ChNC suspension to fruits and vegetables significantly extends their shelf life, thanks to the antimicrobial properties of Cu 2+ ions. The synthesis process of Cu 2+-ChNC is scalable, and the full process only employs materials and chemicals recognized as safe in food by the US Food and Drug Administration (FDA). Our research indicates that Cu 2+-ChNC is a promising material for effectively removing residues and enhancing the postharvest preservation of fruits and vegetables.

A facile, efficient, and high yield method for producing chitin nanocrystals (ChNCs) using ultrasound-assisted phosphoric acid (PA) hydrolysis was developed. The hydrolysis was conducted at high chitin loading of 40 wt

Oligocellulose (OC) with low polydispersity indices has been produced in large quantities using an improved method of acid-assisted hydrolysis, in which long cellulose chains disintegrate in concentrated phosphoric acid at moderately elevated temperatures. The hydrolysis time has been reduced by three orders of magnitude without compromising the overall yield of the process or the quality of OC products. The efficient production of high-quality OCs in large quantities allows for developing OC-derived elastomeric materials. A series of OC-graft-poly(isobornyl methacrylate-random-n-butyl acrylate) [OC-g-P(IBOMA-r-BA)] elastomers have been synthesized via activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). OC-g-P(IBOMA-r-BA) elastomers have tunable molecular architectures and phase morphologies toward desirable mechanical properties and thermal stability suitable for various applications. The methodologies of the OC production and the graft-polymers synthesis in this study would help advance technologies for broader applications of bio-based elastomers.

A PEM fuel cell with the Nafion ionomer phase of the cathode catalyst layer (CL) that was exposed to hot dry gas during the hot-pressing process showed improved performance over the whole current density range and similar to 220% peak power increase with humidified air at 80 degrees C. This enhanced performance is attributed to the modified structure of the perfluorosulfonic acid (PFSA) ionomer layer in the CL during the MEA ' s hot-pressing process. The dry gas exposure above the glass transition temperature (T-g) results in the aggregation of the ionic groups to retain the residue water molecules. This process separates the ionomer into ionic-group-rich domains and ionic-group-sparse domains. The ionic-group-sparse domains create hydrophobic interface and reactant transport channels with lower water content and thus higher oxygen solubility in the ionomer. Accordingly, the water-unsaturated ionomer and its surface hydrophobicity enhance the kinetic-controlled and concentration-polarized regions of the fuel cell polarization curve, respectively. The surface hydrophobicity of the ionomer layer is analyzed by the contact angle measurement and XPS. The durability of the hydrophobic effect below T-g is demonstrated by boiling the treated material. Re-treating the hydrophobic sample with humidified gas exposure above T-g eventually exhibits hydrophilic features, further proving the manipulability of the ionic group distribution.

Ion exchange membranes are widely used to selectively transport ions in various electrochemical devices. Hydroxide exchange membranes (HEMs) are promising to couple with lower cost platinum-free electrocatalysts used in alkaline conditions, but are not stable enough in strong alkaline solutions. Herein, we present a Cu 2+ -crosslinked chitosan (chitosan-Cu) material as a stable and high-performance HEM. The Cu 2+ ions are coordinated with the amino and hydroxyl groups of chitosan to crosslink the chitosan chains, forming hexagonal nanochannels (~1 nm in diameter) that can accommodate water diffusion and facilitate fast ion transport, with a high hydroxide conductivity of 67 mS cm −1 at room temperature. The Cu 2+ coordination also enhances the mechanical strength of the membrane, reduces its permeability and, most importantly, improves its stability in alkaline solution (only 5% conductivity loss at 80 °C after 1,000 h). These advantages make chitosan-Cu an outstanding HEM, which we demonstrate in a direct methanol fuel cell that exhibits a high power density of 305 mW cm −2 . The design principle of the chitosan-Cu HEM, in which ion transport channels are generated in the polymer through metal-crosslinking of polar functional groups, could inspire the synthesis of many ion exchange membranes for ion transport, ion sieving, ion filtration and more.

A method of producing oligomeric chitin using sonication-assisted phosphoric acid hydrolysis was introduced. The processing was continuous and scalable. Oligomeric chitin fractions with narrow distributions of degree of polymerization were obtained by differential precipitation using ethanol as precipitating agent at different ethanol-to-phosphoric-acid-solution volume ratios. The yield of oligomeric chitin with degree of polymerization between 4 and 10 was ≈30% (mass fraction). The content of each fraction was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI TOF MS). Changes in chemical composition of oligomeric chitin were negligible, as verified by MALDI TOF MS, Fourier-transform infrared, and nuclear magnetic resonance spectroscopy. This new method for producing oligomeric chitin molecules is rapid, cost-effective, and safe.

An optical fiber was modified at the tip with a self-assembled plasmonic metamaterial that acts as a miniature surface-enhanced Raman spectroscopy (SERS) substrate. This optical fiber-based device co-localizes the laser probe signal and the chemical analyte at a distance remote from the spectrometer, and returns the scattered light signal to the spectrometer for analysis. Remote SERS chemical detection is possible in liquids and in dried samples. Under laboratory conditions, the analyte SERS signal can be separated from the background signal of the fiber itself and the solvent. An enhancement factor greater than 35,000 is achieved with a monolayer of the SERS marker 4-aminothiophenol.

Diblock copolymer thermoplastic elastomers (TPEs) of poly(methyl methacrylate)-block-poly(n-butyl acrylaterandom-vinylimidazole) [PMMA-b-P(BA-r-VI)] have been designed and synthesized as a model system for demonstrating simultaneously tailoring photoluminescence (PL) and mechanical properties of TPEs via lanthanide coordination. Europium ions with red PL and terbium ions with green PL have been incorporated in TPEs to coordinate imidazole groups on soft blocks. PL spectra can be continuously tuned by varying both the overall ion composition and their relative portions. The rubber elasticity of TPEs arises from entropic restoring of entangled coil chains in the soft matrix filled with glassy PMMA microdomains as physical cross-links. Upon incorporating lanthanide ions, a second network forms due to the lanthanide coordination cross-linkages among soft P(BA-r-VI) chains. Synergistic interactions and reinforcement of local and global networks greatly enhance both the tensile strength and toughness of TPEs without compromising the stretchability and elasticity. In situ small-angle X-ray scattering reveals deformation and relaxation of microstructures upon cyclic uniaxial stretching and recovery. The novel strategy in the design and synthesis of TPEs with tunable optical and mechanical properties enables a wide range of smart materials and technologies.

Supramolecular frameworks have been widely synthesized for ion transport applications. However, conventional approaches of constructing ion transport pathways in supramolecular frameworks typically require complex processes and display poor scalability, high cost, and limited sustainability. Here, we report the scalable and cost-effective synthesis of an ion-conducting (e.g., Na+) cellulose-derived supramolecule (Na-CS) that features a three-dimensional, hierarchical, and crystalline structure composed of massively aligned, one-dimensional, and ångström-scale open channels. Using wood-based Na-CS as a model material, we achieve high ionic conductivities (e.g., 0.23 S/cm in 20 wt% NaOH at 25 °C) even with a highly dense microstructure, in stark contrast to conventional membranes that typically rely on large pores (e.g., submicrometers to a few micrometers) to obtain comparable ionic conductivities. This synthesis approach can be universally applied to a variety of cellulose materials beyond wood, including cotton textiles, fibers, paper, and ink, which suggests excellent potential for a number of applications such as ion-conductive membranes, ionic cables, and ionotronic devices.

Cotton textiles are ubiquitous in daily life and are also one of the primary mediums for transmitting viruses and bacteria. Conventional approaches to fabricating antiviral and antibacterial textiles generally load functional additives onto the surface of the fabric and/or their microfibres. However, such modifications are susceptible to deterioration after long-term use due to leaching of the additives. Here we show a different method to impregnate copper ions into the cellulose matrix to form a copper ion-textile (Cu-IT), in which the copper ions strongly coordinate with the oxygen-containing polar functional groups (for example, hydroxyl) of the cellulose chains. The Cu-IT displays high antiviral and antibacterial performance against tobacco mosaic virus and influenza A virus, and Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Bacillus subtilis bacteria due to the antimicrobial properties of copper. Furthermore, the strong coordination bonding of copper ions with the hydroxyl functionalities endows the Cu-IT with excellent air/water retainability and superior mechanical stability, which can meet daily use and resist repeated washing. This method to fabricate Cu-IT is cost-effective, ecofriendly and highly scalable, and this textile appears very promising for use in household products, public facilities and medical settings.

The classical method of producing cellulose oligomers through hydrolysis of microcrystalline cellulose (MCC) in phosphoric acid has been re-examined. Hydrolysis products are fractionated by precipitation to yield two types of cellulose oligomers with different average degrees of polymerization (DP). The number- and weight-averaged molecular weights of the lower DP fraction are 1339 g/mol and 1388 g/mol respectively, corresponding to a polydispersity index of 1.04. The cellulose oligomer forms type-II crystal, and can be dissolved in both alkaline aqueous solutions and dimethyl sulfoxide. The X-ray and neutron small angle scattering of the cellulose oligomers in solution can be described as rigid slabs.

All-cellulose nanocomposites have been produced from cellulose nanofiber (CNF) suspensions and molecular coil solutions. Morphology and small-angle neutron scattering studies show the exfoliation and dispersion of CNFs in aqueous suspensions. Cellulose solutions in mixtures of ionic liquid and organic solvents were homogeneously mixed with CNF suspensions and subsequently dried to yield cellulose composites comprising CNF and amorphous cellulose over the entire composition range. Tensile tests show that stiffness and strength quantities of cellulose nanocomposites are the highest value at ca. 20% amorphous cellulose, while their fracture strain and toughness are the lowest. The inclusion of amorphous cellulose in cellulose nanocomposites alters their water uptake capacity, as measured in the ratio of the absorbed water to the cellulose mass, reducing from 37 for the neat CNF to less than 1 for a composite containing 35% or more amorphous cellulose. This study offers new insights into the design and production of all-cellulose nanocomposites.

Oligomeric cellulose with an average degree of polymerization of 7.68 and a polydispersity of 1.04 has been fractionated using solution processes. Three fractions have been obtained through initial dissolution, subsequent crystallization, and solvent precipitation, respectively. The resulting oligocellulose fraction has an average degree of polymerization of 7.70 and a polydispersity of 1.01, respectively. Cellulose IV2 crystals form in the oligocellulose fraction, and reversibly transform to II and back to IV using simple solvents.

This paper explores the use of fatty acids in silicone hydrogel contact lenses for extending the release duration of cationic drugs. Drug release kinetics was dependent on the carbon chain length of the fatty acid loaded in the lens, with 12-, 14- and 18-carbon chain length fatty acids increasing the uptake and the release duration of ketotifen fumarate (KTF) and tetracaine hydrochloride (THCL). Drug release kinetics from oleic acid-loaded lenses was evaluated in phosphate buffer saline (PBS) at different ionic strengths (I = 167, 500, 1665 mM); the release duration of KTF and THCL was decreased with increasing ionic strength of the release medium. Furthermore, the release of KTF and THCL in deionized water did not show a burst and was significantly slower compared to that in PBS. The release kinetics of KTF and THCL was significantly faster when the pH of the release medium was decreased from 7.4 towards 5.5 because of the decrease in the relative amounts of oleate anions in the lens mostly populated at the polymer–pore interfaces. The use of boundary charges at the polymer–pore interfaces of a contact lens to enhance drug partition and extend its release is further confirmed by loading cationic phytosphingosine in contact lenses to attract an anionic drug.

Although solid-state lithium (Li)-metal batteries promise both high energy density and safety, existing solid ion conductors fail to satisfy the rigorous requirements of battery operations. Inorganic ion conductors allow fast ion transport, but their rigid and brittle nature prevents good interfacial contact with electrodes. Conversely, polymer ion conductors that are Li-metal-stable usually provide better interfacial compatibility and mechanical tolerance, but typically suffer from inferior ionic conductivity owing to the coupling of the ion transport with the motion of the polymer chains1–3. Here we report a general strategy for achieving high-performance solid polymer ion conductors by engineering of molecular channels. Through the coordination of copper ions (Cu2+) with one-dimensional cellulose nanofibrils, we show that the opening of molecular channels within the normally ion-insulating cellulose enables rapid transport of Li+ ions along the polymer chains. In addition to high Li+ conductivity (1.5 × 10−3 siemens per centimetre at room temperature along the molecular chain direction), the Cu2+-coordinated cellulose ion conductor also exhibits a high transference number (0.78, compared with 0.2–0.5 in other polymers2) and a wide window of electrochemical stability (0–4.5 volts) that can accommodate both the Li-metal anode and high-voltage cathodes. This one-dimensional ion conductor also allows ion percolation in thick LiFePO4 solid-state cathodes for application in batteries with a high energy density. Furthermore, we have verified the universality of this molecular-channel engineering approach with other polymers and cations, achieving similarly high conductivities, with implications that could go beyond safe, high-performance solid-state batteries. By coordinating copper ions with the oxygen-containing groups of cellulose nanofibrils, the molecular spacing in the nanofibrils is increased, allowing fast transport of lithium ions and offering hopes for solid-state batteries.

Synthetic fibres such as polyester and carbon are used in a broad variety of industries. However, as they derive from petrochemicals that are neither renewable nor biodegradable, the development of natural alternatives has gained increasing momentum in recent years. Here, we report a top-down approach for scalable production of cellulose macrofibres from bamboo stems involving a mild delignification process followed by water-assisted air-drying. Consisting of aligned and densely packed cellulose nanofibrils that possess strong hydrogen bonds and van der Walls forces, the extracted fibres exhibit a tensile strength of 1.90 ± 0.32 GPa, a Young’s modulus of 91.3 ± 29.7 GPa and a toughness of 25.4 ± 4.5 MJ m −3 , which exceed those of wood-derived fibres and are comparable to synthetic carbon analogues. As a result of the low density, the specific strength is as high as 1.26 ± 0.21 GPa cm −3 g −1 , surpassing most reinforcing components such as steel wire, synthetic polymers and vitreous fibres. The life-cycle assessment reveals that replacing polymer and carbon fibres in structural composites with the current natural fibres leads to substantial reduction in carbon emissions. Our work suggests a pathway towards sustainability in wider areas of application, including automobiles, aeronautics and construction.