A Cellulose/Chitosan Dual Cross-Linked Multifunctional and Resilient Hydrogel for Emergent Open Wound Management.

Adhesive hydrogel holds huge potential in biomedical applications, such as hemostasis and emergent wound management during outpatient treatment or surgery. However, most adhesive hydrogels underperform to offer robust adhesions on the wet tissue, increasing the risk of hemorrhage and reducing the fault tolerance of surgery. To address this issue, this work develops a polysaccharide-based bioadhesive hydrogel tape (ACAN) consisting of dual cross-linking of allyl cellulose (AC) and carboxymethyl chitosan (CMCS). The hygroscopicity of AC and CMCS networks enables ACAN to remove interfacial water from the tissue surface and initializes a physical cross-link instantly. Subsequently, covalent cross-links are developed with amine moieties to sustain long-term and robust adhesion. The dual cross-linked ACAN also has good cytocompatibility with controllable mechanical properties matching to the tissue, where the addition of CMCS provides remarkable antibacterial properties and hemostatic capability. Moreover, compared with commercially available 3 M film, ACAN provides an ultrafast wound healing on tissue. The ACAN hybrid hydrogels have advantages such as biocompatibility and antibacterial, hemostatic, and wound healing properties, shedding new light on first-aid tape design and advancing the cellulose-based materials technology for high-performance biomedical applications.

Anti-mold, self-cleaning superhydrophobic bamboo fiber/polypropylene composites with mechanical durability.

Bamboo fiber/polypropylene composites (BPCs) have been widely used in buildings, interior decoration, and automobile components. However, pollutants and fungi can interact with the hydrophilic bamboo fibers on the surface of Bamboo fiber/polypropylene composites, degrading their appearance and mechanical properties. To improve their anti-fouling and anti-mildew properties, a superhydrophobic modified Bamboo fiber/polypropylene composite (BPC-TiO2-F) was fabricated by introducing titanium dioxide (TiO2) and poly(DOPAm-co-PFOEA) onto the surface of a Bamboo fiber/polypropylene composite. The morphology of BPC-TiO2-F was analyzed by XPS, FTIR, and SEM. The results showed that TiO2 particles covered on Bamboo fiber/polypropylene composite surface via complexation between phenolic hydroxyl groups and Ti atoms. Low-surface-energy fluorine-containing poly(DOPAm-co-PFOEA) was introduced onto the Bamboo fiber/polypropylene composite surface, forming a rough micro/nanostructure that endowed BPC-TiO2-F with superhydrophobicity (water contact angle = 151.0° ± 0.5°). The modified Bamboo fiber/polypropylene composite exhibited excellent self-cleaning properties, and a model contaminant, Fe3O4 powder, was rapidly removed from the surface by water drops. BPC-TiO2-F showed excellent anti-mold performance, and no mold was on its surface after 28 days. The superhydrophobic BPC-TiO2-F had good mechanical durability and could withstand sandpaper abrasion with a weight load of 50 g, finger wiping for 20 cycles, and tape adhesion abrasion for 40 cycles. BPC-TiO2-F showed good self-cleaning properties, mildew resistance, and mechanical resistance, giving it promising applications for automotive upholstery and building decoration.

Robust cellulose-based hydrogel marbles with excellent stability for gas sensing.

Liquid marbles, as particle-armored droplets, have potential applications in microreactors, biomedicine, controlled release and gas detection. To improve the stability and biocompatibility of marble, biocompatible cellulose acetate particles and 3-allyloxy-2-hydroxy-propyl-cellulose (AHP-cellulose) were used to fabricate robust cellulose-based liquid marbles with excellent stability. Liquid marble was gelled into hydrogel marble via blue-light-irradiated polymerization of AHP-cellulose. The mechanical properties of cellulose-based hydrogel marble are superior to those of liquid marble. The rupture height of liquid marble is 10.5 m, which is 420 times greater than that of water marble (0.025 m). Surprisingly, the hydrogel marble with a 3 % AHP-cellulose concentration remained intact even after being dropped from a height of 50 m, which is comparable with the ability of a leather ball to withstand larger impact. When released from a height of 60 mm, hydrogel marble bounced to approximately 25.5 mm, 881 % higher than liquid marble (2.6 mm). Hydrogel marble exhibited long-lasting stability and was capable of monitoring ammonia with a detection limit of 365.2 mg/m3. The biocompatible cellulose-based hydrogel marble with excellent mechanical stability and reusability detection has great potential in chemical and environmental engineering as gas sensors.

Engineered Janus cellulose membrane with the asymmetric-pore structure for the superhigh-water flux desalination.

Membranes are the dominant material for seawater desalination and clean-water harvesting, which are commonly composed of synthetic polymers, showing low hydrophilicity and environmental hazard. Herein, we developed a low-cost, intrinsically green, superhigh-water flux Janus cellulose membrane (CEM) via a facile cellulase etching strategy. Coating cellulase on the single surface of cellulose membrane (such as top surface), triggers effective etching on its top section rather than bottom section, which architects an asymmetric-pore structure of the Janus CEM including porous top-and dense bottom-layer. Such distinction endows the Janus CEM with an unprecedented high-water flux of 135.75 LMH and a low salt-water ratio of 0.29 g·L-1 for 1 M NaCl solution, which is 17-time higher and 62-time lower than that of the pristine CEM. Our Janus CEM enables a promising participant for the advanced membrane materials toward versatile separation engineering.

Mussel-Inspired Magnetic Dissolving Pulp Fibers Toward the Adsorption and Degradation of Organic Dyes.

In this work, a simple synthetic method was used to prepare a new type of magnetic dissolving pulp (MDP) @polydopamine (PDA) fibers. The hydroxyl groups of the fibers were converted into carboxyl groups after succinylation. Fe3O4 nanoparticles were grown in situ on the fibers. The prepared MDP@PDA fibers have catalytic reduction efficiency and adsorption performance for methylene blue organic dyes, and it has been thoroughly tested under various pH conditions. Fe3O4@PDA fibers have high reusability, are easy to separate, and regenerate quickly. The catalytic and adsorption efficiency barely decreases after repeated use. The surface of dissolving pulp fibers with a functionalized multifunctional PDA coating is used to create multifunctional catalysts and adsorbent materials. This study presents a very useful and convenient method for the synthesis and adjustment of MDP@PDA fibers, which have a wide range of potential applications in catalysis and wastewater treatment.

Self-Healing Cellulose Nanocrystals-Containing Gels via Reshuffling of Thiuram Disulfide Bonds.

Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into gels via polyaddition. By the reshuffling of thiuram disulfide bonds, the CNC-containing gels repair the crack and recover mechanical properties rapidly under visible light in air. The thiuram disulfide-functionalized gels with a CNC content of 2.2% are highly stretchable and can be stretched approximately 42.6 times of their original length. Our results provide useful approaches for the preparation of dynamic CNC-containing gels with implications in many related engineering applications.

Robust superhydrophobic and superoleophilic filter paper via atom transfer radical polymerization for oil/water separation.

Robust superhydrophobic and superoleophilic cellulose-g-PFOEMA filter paper membranes were fabricated via surface grafting of poly(perfluorooctylethyl methacrylate) (PFOEMA) using atom transfer radical polymerization (ATRP). The surface chemical compositions, morphologies and wettability of cellulose-g-PFOEMA with different degree of graft ratio (DG) were investigated using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and contact angle (CA) measurement. IR and XPS showed that PFOEMA were introduced into surface of filter paper. The superhydrophobicity of filter paper increased with amount of PFOEMA grafted. When DG of grafted PFOEMA was higher than 11.2%, the superhydrophobicity reached a steady state and the measured water contact angle was about 157°. The PFOEMA-grafted filter paper exhibited excellent chemical resistance toward a wide range of pH solution from 1 to 12. Cellulose-g-PFOEMA is convenient for oil/water separation with efficiency higher than 95%. The excellent reusability and stability make cellulose-g-PFOEMA filter paper membrane a promising candidate in the applications of oil spillage cleanup and the separation of oil/water mixture.