Chao Ma

Biomass‐based multifunctional hydrogels with high mechanical strength, fatigue resistance, and electrical conductivity are promising materials for the fabrication of flexible electronic devices. However, achieving mutually exclusive properties simultaneously remains challenging. Herein, a novel luffa sponge (LS) composite multi‐functional hydrogel (WLSHG) is prepared. The LS is dignified to create a flexible 3D skeleton, which is then polymerized with polyacrylamide in situ using a tannic acid–ferric ions reoxidation system. Benefiting from the strong physical support of the LS skeleton and multiple interactions between molecules in the system, synergistically enhanced the mechanical properties of the hydrogel. The compressive strength and modulus of the WLSHG increased by 557% and 2000%, respectively, compared with the pristine hydrogels. And the honeycomb‐like microchannels in the LS bundle facilitated efficient ion transport, resulting in an ionic conductivity of 0.124 S m ⁻¹ for WLSHG. The WLSHG‐based flexible strain sensor exhibited excellent sensitivity (2.03 kPa ⁻¹ ) and stability (>1000 cycles) over a wide pressure range. By integrating this sensor into an array and using Internet of Things and machine learning technologies, its ability is successfully demonstrated to accurately recognize human sitting position and gait patterns. This study presents a promising approach for fabricating high‐performance biomass‐based hydrogels for flexible electronic devices.

Soybean protein adhesives are environmentally friendly biomass‐based aldehyde‐free adhesives that have good economic value for the wood industry; however, it remains challenging to produce soybean protein adhesives with excellent water resistance, toughness, and mildew resistance through a simple modification method. In this work, inspired by plant polyphenols, a novel crosslinked soybean meal adhesive (SMPT) is obtained using a facile economic method. Polyamidoamine‐epichlorohydrin (PAE) and tannic acid (TA) are combined with a soybean meal matrix to form a tough co‐crosslinked network through strong intermolecular forces (covalent bonds, ionic bonds, and hydrogen bonds) in adhesive system. The results show that the wet bonding strength of SMPT adhesives for plywood is 134.1% higher than the unmodified soybean meal adhesive. The adhesion properties met the standard requirements for interior‐use plywood. And the compact cross‐linking network structure is accelerated the greater energy dissipation, which improves the toughness of adhesive. Moreover, cationic azetidinium groups in PAE and phenol hydroxyl groups in TA synergistically not only exhibit the good antibacterial activities but also improve mildew resistance for SMPT adhesives. This facile strategy provides an economic sustainable method to prepare high‐performance environmentally friendly wood adhesives.

Multifunctional hydrogels that integrate stretchability, adhesion, self-healing, and antibacterial properties may find use in a variety of fields including electronic skin, wound dressings, and wearable devices; however, traditional hydrogels often exhibit short-term adhesiveness, poor mechanical properties, and a lack of antibacterial activity. Herein, a plant-inspired polyacrylamide-soybean protein isolate-pyrogallol/borax (PAM-SPI-P/B) hydrogel has been developed using a facile green method based on dynamic coordination cross-linking between pyrogallol (PG) and borax. The PG–borax dynamic bonds adjusted the network structure of the hydrogels to provide greater structural integrity to the PAM–SPI double network. This hydrogel possessed a high mechanical strength (large elongation up to 760% and compressive strength up to 1.25 MPa at 80% strain), low swelling ratio, and self-healing properties. Inspired by natural polyphenols that contain adhesive molecules, the addition of pyrogallol provided the hydrogel excellent adhesion to various hydrophilic and hydrophobic substrates. And with the inhibition of pyrogallol autoxidation due to the borax protection, the hydrogel showed repeatable and durable adhesion over 20 cycles. The obtained hydrogels also exhibited good antibacterial activities against Escherichia coli and Staphylococcus aureus because they were based on pyrogallol and borax, which have antibacterial properties. Accordingly, we envision that the PAM-SPI-P/B hydrogels have great potential for use in biomimetic tissues and biosensors.