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Lignocellulosic nanofibril (LCNF) is indispensable in numerous potential applications because of its unsurpassed quintessential characteristics. While it still remains a challenge to assemble LCNF in a facile and environmental economy-first manner. In this work, a simple and green one-step synthetic approach was reported to prepare a series of LCNF-containing versatile hydrogels using deep eutectic solvent (DES). In particular, the LCNF5% hydrogel (namely LCNF5%-gel) in this work perfectly integrated superior stretchability (∼643 %), and displayed a dramatically improved anti-swelling ability (25 %) compared to the control sample (neat DES hydrogel, 2252 %). Simultaneously, the LCNF5% hydrogel presented underwater adhesiveness and outstanding long-term low-temperature resistance (stable at -25 °C for a month). This novel multifunctional hydrogel, prepared by a facile and eco-friendly strategy, is potentially useful in wet adhesion or underwater applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Conductive hydrogels have attracted significant attention as a promising material in electrical and biomedical fields. However, the simultaneous realization of good conductivity, toughness, high tissue adhesiveness, excellent biocompatibility, and extreme environmental tolerance remains a challenge. Inspired by the antifreezing/antiheating behavior of natural plants, a calcium chloride/TEMPO-oxidized cellulose nanofiber-dopamine/ polyacrylamide (CaCl 2 /TOCNF-DOPA/PAM) glycerol/water organohydrogel with antifreezing and antiheating properties, good transparency, conductivity, stability, excellent biocompatibility, mechanical properties, and tissue adhesiveness was fabricated. The organohydrogel has about 700% stretchability, with about 90% transparency. The organohydrogel exhibits good conductivity of 4.9 × 10 -4 S/cm and high tissue adhesiveness of 50 kPa, which can monitor various human activities. The organohydrogel displays excellent extreme environmental tolerance to maintain the conductivity and mechanical properties under an extremely wide temperature range (-24 to 50 °C) for a long period due to its water-locking effect between glycerol and water molecules. The biocompatible organohydrogel is able to protect the skin from frostbite or burns in harsh environments. The plant-inspired stable and durable organohydrogel is used as a wearable dressing for multifunctional sensors., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The gradually depleting fossil resources and the biosafety of bisphenol A have always restricted the green development of the traditional epoxy resin field. In this Article, biomass macromolecule lignin sulfonates are selected as the raw material instead of traditional bisphenol A to prepare lignin-based epoxy resin adhesives. Lignin sulfonates are chemically modified and combined with a cross-linking agent to form lignin-based epoxy resin adhesives with double-interpenetrating-network structures. The resulting lignin-based epoxy adhesive exhibits a maximum tensile shear strength of 11.29 MPa, which is 213% higher than the strength before chemical modification. The tensile shear strength of the adhesive is still 10.13 MPa after 12 h of immersion in water (20 °C), and its tensile shear strength is 9.30 MPa after 12 h of immersion in boiling water (100 °C). The high-temperature and high-humidity environment has no significant effect on the properties of the resulting lignin-based epoxy adhesive.

Polydopamine (PDA)-based self-adhesive hydrogel sensors are extensively explored but it is still a challenge to construct PDA-based hydrogels by free radical polymerization. Herein, a new approach to construct self-adhesive hydrogels by conducting free radical polymerization in both aqueous phase and micelle phase is developed. The following two-phase polymerization processes account for the formation of the self-adhesive hydrogels. The first one is the polymerization of acrylamide (AM) and dopamine (DA) in aqueous phase to form adhesive component PAM-PDA (PAM, polyacrylamide; PDA, polydopamine). The second one is the polymerization of hydrophobic monomer 2-methoxyethyl acrylate (MEA) in micelles of an amphiphilic block copolymer Pluronic F127 diacrylate (F127DA). The poly(2-methoxyethyl acrylate) (PMEA) networks help to maintain the high robustness of the hydrogel. Because PMEA and PDA form in relatively separated phases, the inhibition effect of PDA on the free radical polymerization process of PMEA is weakened. Based on this mechanism, mechanically strong and adhesive hydrogels are achieved. The introduced ions during preparation process, such as Na + , OH - and K + , endow the resulting hydrogels ionic conductivity. Resistive strain sensor of the hydrogel achieves a high gauge factor (GF) of 5.26, a response time of 0.25 s and high sensing stability. Because of the adhesiveness, such hydrogel sensor can be applied as wearable sensors in monitoring various human motions. To further address the freezing and drying problems of the hydrogels, organohydrogels are constructed in glycerol-water mixed solvent. The organohydrogels exhibit outstanding anti-freezing property and moisture retention ability, and their adhesiveness is well maintained in subzero conditions. Capacitive pressure sensors of the organohydrogels possessing a GF of 2.05 kPa -1 , high sensing stability and reversibility, are demonstrated and explored in monitoring diverse human motions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Lignin is a good candidate for the polymerization and chemical modification to prepare sustainable chemicals and materials, but a relatively low hydroxyl content becomes an obstacle for the preparation of lignin-based polyurethane (PU) adhesives. In order to improve its reactivity, the acetic acid lignin (AAL) was hydroxymethylated before copolymerized with isocyanate during the preparation of PU adhesives. The hydroxymethylation was carried out in an alkaline formaldehyde solution and it was found that 85 °C is the optimal temperature. On that condition, the free formaldehyde content of the corresponding product HL-6 was as low as 0.32%, while the hydroxymethyl was increased by 189.11% compared with original AAL and reached 2.92 mmol/g. In the polymerization of PU adhesives, the hydroxymethylated lignin with a higher aliphatic hydroxyl content formed a more compact three-dimensional urethane cross-linking network with isocyanate. The mechanical properties and thermal stability of the lignin-based PU adhesive were improved by 15-30 wt% in HL-6, and particularly the tensile strength was increased by 21-41 MPa, which indicated that the hydroxymethylation is an efficient way to enrich the hydroxyl in lignin, and the modified lignin is adequate to partially replace petroleum-based polyols for the preparation of PU adhesives with excellent properties., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Diatoms secrete extracellular polymeric substances (EPS), or mucilage, around the cell wall that may serve to aid in motility and form a discrete layer that may help maintain thicker layers of EPS that have a greater role in adhesion. Mucilage molecules adhere to the diatom frustules, which are biosilica skeletons that develop from the diatom cell walls. Here, molecular dynamics methods were used to determine the characteristics of mucilage molecules as a function of pore size; notably 1,4-α-D-galacturonic acid, 1,4-β-glucuronic acid and 1,4-β-D-mannuronic acid. These uronic acids differ from each other in structure and extensibility as a function of their folding characteristics. Here, we find that when overlain upon a pore, mucilage molecules try to return to their native folded states but are restrained by their interactions with the silica surfaces. Furthermore, the extensibility of mucilage molecules over pore spaces affects the extent of mechanical energy required to straighten them. As such, different EPS molecules will affect sliding, friction and adhesion to subsequent layers of EPS in different ways. We conclude that higher EPS extensibility is homonymous with higher adhesive or frictive resistance since the molecules will be able to strain more before they reach the most extended (and thus rigid) conformation. The research herein is applicable to modern engineering as it yields insight into the biomimetic design of molecules and surfaces for improved adhesion or motility., (Copyright © 2017 Elsevier Ltd. All rights reserved.)