Hydrogels are often limited in their applications due to their inherently weak mechanical properties. In this study, a carboxyl-functionalized hyperbranched polymer (HPEHO-star-PAA) was synthesized and used as a macromolecular physical cross-linker to enhance the mechanical properties of conductive hydrogels. Fe3+-carboxyl complexes were incorporated into the P(AAm-co-AA)/HPEHO-star-PAA hydrogel to form a dual cross-linked network structure. The cross-linker N,N ' methylenebis(acrylamide) (MBA) was chemically incorporated into the network to form covalent cross-links, strengthening the network. Meanwhile, the coordination bonds formed between Fe3+ and carboxylate act as dynamic noncovalent cross-links, enhancing the energy dissipation capacity. This study successfully prepared a hydrogel with excellent mechanical properties, including an elongation at break of 573%, a tensile strength of 3.68 MPa, and a toughness of 14.09 MJ/m3. Additionlly, the conductive hydrogels also showed good antiswelling ability due to the strong binding force between Fe3+ and carboxylate. Moreover, P(AAm-co-AA) hydrogels used as strain sensors possessed stability and were highly sensitive. Therefore, this well-designed conductive hydrogel, with high mechanical strength, excellent toughness, good antiswelling ability, and high sensitivity, shows great potential for use in flexible strain sensor applications.

Solar-driven interfacial evaporation is a promising technology for seawater desalination; however, most hydrogel-based evaporators rely on energy-intensive freeze-drying processes to construct porous structures and require additional photothermal materials to achieve high evaporation performance. To address these challenges, a freeze-drying-free pressing strategy was developed using waste coffee grounds as the structural framework and sodium alginate as the binder and gel-forming component. Porous coffee-ground-based hydrogel evaporators were fabricated through particle packing and ionic crosslinking. The obtained evaporator exhibited an interconnected porous structure and excellent photothermal conversion capability. Benefiting from the intrinsic broadband light absorption of coffee grounds, as well as the reduced light scattering within pores and enhanced near-infrared absorption after wetting, the average solar absorbance increased from 69.12% in the dry state to over 92.45% in the wet state. Without introducing any additional photothermal materials, the evaporator achieved a high evaporation rate of 2.12 kg m−2 h−1 under 1 sun irradiation and maintained stable performance in saline water. Owing to its particle-assembled architecture, the failed evaporator could be reprocessed by simple repressing while retaining its evaporation performance. Furthermore, outdoor desalination experiments verified its practical freshwater production capability. This work provides a sustainable and low-cost strategy for biomass valorization and scalable fabrication of solar evaporators.

Developing epoxy coatings capable of stable lubrication in aqueous environments remains challenging due to the low viscosity and poor retention of water at sliding interfaces. In this study, a bio-inspired epoxy/polyacrylamide (EP/PAM) composite coating was constructed to achieve hydration-regulated lubrication and water-triggered functional response. Crosslinked polyacrylamide particles were embedded into the epoxy matrix as dispersed water-storage units, enabling constrained swelling and surface reconstruction upon water exposure, thereby regulating the interfacial hydration state and real contact behavior. By tailoring particle content and crosslink density, the lubrication performance could be rationally controlled. The optimized EP/PAM1-25 coating exhibited a minimum coefficient of friction of 0.10 and a specific wear rate of 0.91 *10-4 mm3 center dot N-1 center dot m- 1, corresponding to reductions of approximately 60% and 80%, respectively, compared with pure epoxy. The tribological performance showed a non-monotonic dependence on crosslink density, reflecting the balance between swelling capacity and interfacial lubrication stability. The coating maintained low friction under varying loads and sliding speeds. Device-level demonstrations further confirmed pressure-driven drainage and leakagetriggered alarm activation enabled by water-induced friction transition. This work provides a controllable strategy for designing adaptive hydration-lubricated coatings and broadens their potential in water-responsive systems.

Nanoparticle reinforcement in hydrogels is typically limited by low loading levels, which restricts their mechanical enhancement and fails to endow intrinsic antifreeze capability. Here, we break this paradigm by incorporating exceptionally high contents of nano-silica (SiO2) into polyacrylamide (PAM) hydrogels, forming a nanoscale hard-soft dual-network structure. The resulting hydrogels exhibit remarkable mechanical robustness (tensile strength 5.37 MPa, compressive strength 305.52 MPa, tearing strength 1.48 MPa) and retain superior flexibility at -20 degrees C (tensile strength 11.4 MPa, elongation at break 654%), demonstrating intrinsic antifreeze performance. Mechanistic studies reveal that abundant hydrogen bonding between SiO2, PAM chains, and water molecules, coupled with nanoscale confinement, effectively reduces the freezable water fraction. Moreover, high SiO2 loading imparts dual rheological behaviors to the precursor solution, enabling both solid-like processability and fluid-like flowability. Notably, the nanocomposite hydrogels possess outstanding wear resistance in the dry state and maintain relatively high friction coefficients underwater, ensuring stable gripping under wet conditions. This work establishes a universal high-loading nanoparticle strategy for constructing hydrogels that integrate mechanical strength, antifreeze capability, and multifunctionality, opening new opportunities in flexible electronics, soft robotics, and extreme-environment protection.

Flexible sensors and their arrays show great potential in health monitoring, wearable electronics, and soft robotics. However, challenges remain in reliably distinguishing different strain types, achieving adaptability to underwater environments. In this work, a tubular flexible strain sensor and array were fabricated on an elastomeric substrate via a sacrificial templating technique, with a conductive carbon black (CB) layer integrated along the inner wall of the resulting hollow channel. The sensor can effectively distinguish tensile, compressive, and bending strains by analyzing the trends of resistance variation. It exhibits a wide strain detection range, rapid response, and excellent cyclic stability. Moreover, the sensor is capable of recognizing complex deformation modes such as pinch-lift and press-push actions. The unique tubular architecture prevents direct contact between the CB layer and the external environment, enabling underwater strain sensing. By employing a cross-assembly strategy, a sensor array was fabricated using the tubular sensors, which inherits the ability to identify complex strain patterns and can be applied in underwater environments. This array allows for real-time monitoring of joint motion characteristics at various positions on the human body, providing valuable insights into joint kinematics and offering promising applications in wearable sensing and soft robotic motion perception.

Solar interfacial evaporation technology holds significant potential for applications in seawater desalination and wastewater treatment. However, the development of low-cost, highly efficient, and stable evaporators remains challenging. In this study, a sponge-like porous hydrogel (CAFC) was prepared by using chitosan (CS), pulp fibers (PF), and carbon nanotubes (CNTs) as raw materials through glutaraldehyde (GA) cross-linking and freeze-induced pore formation, and was subsequently applied in solar interfacial evaporation. The results demonstrated that the Schiff base cross-linked network formed between GA and CS confers excellent structural stability to the material, the fiber scaffold constructed by PF improved the porous structure and promote water transport, while CNTs provide superior light absorption and photothermal conversion capabilities. The optimized CAFC-4 hydrogel exhibited a light absorption rate exceeding 90% over the wavelength range of 250-2500 nm, with a pure water evaporation rate of 2.66 kg m⁻² h⁻¹ under 1 sun irradiation and a solar evaporation efficiency of 84.4%. In a 10 wt.% NaCl solution, the evaporation rate remained at 1.93 kg m⁻² h⁻¹ and demonstrated good stability during cyclic and continuous evaporation. This evaporator can also effectively treat wastewater containing Methylene Blue and Orange I dyes, with no characteristic absorption peaks of the dyes detected in the product water. Outdoor simulated seawater desalination experiments showed that the CAFC-4 evaporator achieved a maximum evaporation rate of 2.06 kg m⁻² h⁻¹ under natural sunlight, with a removal rate of major salt ions exceeding 99.9%. This study provides a simple strategy for constructing a low-cost, biomass-based, high-efficiency solar evaporator.

Due to population growth, climate change, and the continued increase in agricultural and industrial demand, freshwater scarcity has become an urgent global challenge that requires immediate attention. Solar interface evaporation technology, as a promising method for sustainable desalination, has garnered significant attention due to its high energy efficiency and environmental compatibility. This paper reports on a cost-effective and scalable solar evaporator based on commercially available polyethylene terephthalate (PET) fiber sponge with directed capillary channels. First, the PET sponge is modified with a dopamine coating, followed by in situ growth of copper sulfide (CuS) nanoparticles as a photothermal agent. This simple and efficient preparation process requires no complex equipment and is suitable for large-scale production. The resulting evaporator exhibits broadband solar absorption (95.8 %), excellent hydrophilicity, and a unique "surface-bulk" synergistic photothermal conversion mechanism, which enhances light capture, thermal limitation, and directed water transport. Under 1 sun illumination, the 2D and 3D evaporators achieve evaporation rates of 2.19 and 3.78 kg m- 2 h- 1 in pure water, respectively, and 2.04 and 3.64 kg m- 2 h- 1 in 3.5 wt% saline solution, respectively, with a maximum efficiency of 92.8 %. Even under reduced light intensity (0.5 sun), the evaporators maintain competitive performance, achieving evaporation rates of 1.01 kg m- 2 h- 1 and 2.78 kg m- 2 h- 1. This work provides a feasible solution for low-cost, scalable solar evaporators in seawater desalination and broader water purification applications.

ABSTRACTThe inability to observe the evolution of the char layer morphology during the combustion process hinders an in‐depth understanding of the synergistic flame‐retardant mechanism between montmorillonite and expandable flame retardants (IFR). In this study, a novel device for real‐time detection of char layer resistance was used to explore the synergistic flame retardant mechanisms of montmorillonite (MMT) and organically modified montmorillonite (OMMT) in combination with IFR in a styrene‐butadiene‐styrene (SBS) matrix. Thermogravimetric analysis, IR spectroscopy, and x‐ray diffraction tests indicate that both MMT and OMMT can promote the generation of crosslinked structures in the char layer, improving the thermal stability of the char. Additionally, combining real‐time char layer resistance detection with scanning electron microscopy (SEM), it was found that OMMT enhances the expansion and continuity of the char layer, whereas MMT leads to the rupture of the char layer during the expansion process, which affects its flame retardant performance. This study shows that the synergistic effect of OMMT with IFR is superior to that of MMT, mainly because OMMT is better distributed in the SBS matrix, increasing the viscosity of the char layer, inhibiting gas escape, and promoting the expansion and continuity of the char layer.

The demand for smart, durable, and energy-independent lubrication materials in wet or dynamic environments remains unmet due to limitations in conventional stimuli-responsive coatings. Inspired by mucus-secreting fish, which achieve rapid, passive lubrication through internal secretion and structural adaptation, this work presents a water-triggered self-lubricating epoxy coating (EP-HAG) incorporating hydrophobically associated superabsorbent hydrogel (HAG) particles. The design addresses key challenges of conventional systems by enabling spontaneous surface lubrication without external stimuli and by introducing intrinsic self-healing ability. Under wet conditions, the partially exposed HAG particles swell to form a water-rich lubricating layer, while the embedded portion ensures mechanical anchoring. Compared to pure epoxy, the optimized EP-HAG9 coating reduces the coefficient of friction and wear rate by similar to 66.0 % and similar to 86.6 %, respectively, under typical conditions (150 rpm, 5 N). Additionally, the physically crosslinked HAG network enables structural self-repair after shear damage, maintaining long-term low-friction performance. Functional demonstrations, including underwater escape and passive leak-triggered alarms, confirm the coating's potential for intelligent release and sensing. This study offers a biomimetic, energy-free lubrication strategy with broad implications for smart coatings and protective materials in humid or aquatic applications.

This study explores the synergistic flame retardant mechanism of molybdenum trioxide (MoO3) and intumescent flame retardants (IFRs) in a styrene-butadiene-styrene (SBS) matrix using real-time resistance monitoring. By tracking the char layer resistance during combustion and combining multiple characterization techniques, we examined MoO3's impact on the char layer morphology. The results demonstrate that the incorporation of MoO3 enhances the flame-retardant performance of IFR. At 1 wt % MoO3, the UL-94 rating improves from nonclassified to V-1. Thermogravime tric Analysis reveals that MoO3 lowers the initial decomposition temperature of the material from 240 degrees C to 231 degrees C while increasing the char residue. X-ray Photoelectron Spectroscopy and Fourier transform infrared analyses confirm that MoO3 acts as a catalyst, promoting ammonium polyphosphate decomposition and facilitating the formation of phosphate esters, which enhance the char layer's viscosity and compactness. While MoO3 does not directly participate in char crosslinking, it accelerates char formation, improves expansion, and strengthens flame retardancy. Real-time resistance data further indicate that MoO3 reduces char formation time and slows char layer cracking, thereby enhancing flame resistance. This study provides new insights into the MoO3/IFR synergy and introduces a novel approach for monitoring char layer changes during combustion.

Bimodal flexible strain-temperature sensor arrays, capable of simultaneously detecting mechanical and thermal stimuli, show great potential in wearable electronics and human-machine interaction applications. However, existing hydrogel-based bimodal sensors commonly suffer from signal crosstalk, insufficient sensitivity, and poor structural reconfigurability. To address these challenges, this work proposes a modular "building-block" assembly strategy to construct a flexible multimodal hydrogel sensor array with effective strain-temperature signal decoupling and high sensitivity. The strain sensing units are composed of polyacrylamide/chitosan (PAM/CS) hydrogels, while the temperature sensing units are fabricated by sequentially coating chitosan (CS) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on polyacrylamide/sodium alginate (PAM/SA) hydrogels. Electrostatic interactions among CS, SA, and PEDOT:PSS ensure stable interfacial bonding, while Ca2+ crosslinking enhances the rigidity of PAM/SA, inducing strain concentration in the PAM/CS region to achieve signal decoupling. The strain concentration effect significantly improves strain sensitivity with a gauge factor up to 8.82, and the constructed energy-filtering interface elevates the Seebeck coefficient to 128.59 mu V/K, endowing the device with excellent temperature sensing performance (detection limits for strain and temperature difference are 0.1 % and 0.3 degrees C, respectively). Moreover, the hydrogel materials exhibit good cytocompatibility and hemocompatibility, further ensuring their safe integration into wearable systems. This sensor array is applicable in sign language recognition, intelligent password input, and other scenarios, demonstrating broad application prospects.

Strain sensors with high sensitivity and wide detection range are essential for meeting diverse applications, such as precisely monitoring the movement of patients with bone defects during rehabilitation. However, extending the sensing range without compromising sensitivity, particularly for small strains, remains a significant challenge for flexible sensors. Here, a strain redistribution strategy was employed to achieve wide-range and highsensitivity monitoring of natural rubber (NR)-based sensors. A rectangular NR-based sensor was initially developed using the swelling-infiltration method, demonstrating a broad strain range but low sensitivity. The introduction of V-notches on both sides of the sensor resulted in significant local strain enhancement, substantially improving sensitivity but significantly reducing the sensing range. For example, the gauge factor (GF) increased from 4.2 to 28.4 at 20 % strain, while the sensing range decreased from 400.5 % to 71.4 %. Furthermore, O-notches were integrated into the NR-based sensor to facilitate strain redistribution. A welldesigned O-notch enhanced the sensing range by 40 % without sacrificing small-strain sensitivity. Additionally, the NR-based sensor with strain redistribution demonstrated a low detection limit (0.1 %), excellent cyclic stability, and biocompatibility, making it highly effective for detecting large and small deformations in the human body.

The global freshwater crisis and escalating electromagnetic interference (EMI) pollution necessitate the development of multifunctional materials for sustainable water purification and electromagnetic protection. Herein, we propose a biomimetic hierarchical hydrogel featuring a network of carbon nanotubes (CNTs) bridging reduced graphene oxide@polyacrylamide (rGO@PAM) particles within a sodium alginate (SA) matrix to address this dual demand. The rGO@PAM particles were synthesized via in situ reduction of graphene oxide (GO) adsorbed on chemically crosslinked PAM particles, ensuring structural stability and enhanced photothermal conversion. CNTs act as bridging units to construct a three-dimensional thermal-electrical network, synergizing with the vertically aligned porous SA matrix formed by freeze-drying and ionic crosslinking. This unique architecture enables efficient solar interface evaporation (1.80 kgm(-2)h(-1) under 1.0 sun) with exceptional salt resistance (>15 wt% brine) and long-term stability, while the hierarchical conductive network achieves a remarkable EMI shielding effectiveness of 66.10 dB in the hydrated state through absorption-dominated mechanisms. The work offers a scalable paradigm for multifunctional hydrogels in sustainable water purification and flexible electronics protection.

Organic sulfur cathodes for lithium-sulfur (Li-S) batteries hold great promise for suppressing polysulfide shuttling, yet their practical implementation is hindered by sluggish Li+ transport kinetics and intricate synthesis processes. Here, we present a catalyst-free solid-state synthesis strategy to construct a sulfur-containing polymer molecular framework (PEI@TPAL@S) by integrating terephthalaldehyde-based motifs (TPAL) and sulfur clusters into a polyethylenimine (PEI) backbone. The designed framework features abundant nitrogen-active sites and hierarchically interconnected nanopores, synergistically enhancing polysulfide confinement and Li+ diffusion. The PEI@TPAL@S cathode achieves a sulfur content of 77.0 wt %, a Li+ diffusion coefficient 100-fold higher than conventional sulfur-containing polymers and exceptional rate capability (726 mAh g-1 at 5C). Remarkably, it demonstrates ultralong cycling stability with a minimal capacity decay rate of 0.051% per cycle over 500 cycles at 5C. Mechanistic studies reveal that the covalent Li-N bonding and porous architecture facilitate efficient polysulfide adsorption and rapid Li+ transport, while density functional theory (DFT) calculations confirm reduced energy barriers for lithium sulfide nucleation. This work provides a scalable pathway for high-performance organic sulfur cathodes and advances the molecular-level design of sulfur-containing polymers for next-generation energy storage systems.

Conventional lubricants degrade under high temperature, humidity, or dynamic loading due to frictional heat accumulation. Herein, a composite with expanded graphite (ESA) loaded with lithium chloride (LiCl) and impregnated with unsaturated polyester resin (UPR) is developed to enhance lubrication and thermal management. LiCl forms a lubricating layer (coefficient of friction as low as 0.138) by adsorbing moisture, while frictional heat triggers a liquid-gas phase transition, reducing contact temperature by 62 % (to 39.3 degrees C) and preventing matrix degradation. The optimized 2 wt% LiCl composite reduces wear rate by 88.7 %. The ESA skeleton dissipates stress, improving structural stability. This work offers a new strategy for designing highperformance polymer-based friction materials.

Porous hydrogels have emerged as promising matrices for solar interfacial evaporation due to their superior water activation and rapid transport capabilities. However, conventional fabrication techniques, such as freezedrying, are hindered by high energy consumption, complex procedures, and elevated costs. Herein, we report a sponge-like porous composite hydrogel fabricated via a facile cryo-polymerization strategy using acrylic acid, chitosan, and cellulose fibers. The resulting hydrogel exhibits a robust, non-swelling porous architecture with interconnected micron-scale capillaries, integrating the hydrophilicity of hydrogels with the structural stability of sponges. This architecture ensures efficient water delivery and mechanical resilience under compression. Surface modification with CuS nanoparticles endows the system with strong photothermal conversion efficiency. The abundant hydrophilic functional groups (-COOH, -OH, -NH2) effectively reduce the water evaporation enthalpy, achieving a minimum equivalent enthalpy of 1214 J & sdot;g- 1. Under standard solar irradiation (1.0 sun), the evaporator delivers high evaporation rates of 2.79 kg & sdot;m- 2 & sdot;h- 1 in pure water and 2.40 kg & sdot;m- 2 & sdot;h- 1 in 3.5 wt% saline, with excellent long-term cycling stability. Furthermore, the hydrogel demonstrates notable photocatalytic activity toward organic dye degradation, highlighting its multifunctional potential for sustainable water treatment.

Both molybdenum trioxide (MoO3) and organo-modified montmorillonite (OMMT) serve as synergists in intumescent flame-retardant (IFR) systems, yet their distinct mechanisms complicate elucidation of their combined effects. In this study, an styrene-butadiene-styrene (SBS)/IFR composite containing OMMT/MoO3 was developed, and real-time electrical resistance monitoring of the char layer was used to investigate the synergistic flame-retardant mechanism. Results showed that combining OMMT and MoO3 enhanced flame retardancy and char stability, with 2 wt% OMMT achieving the best performance (UL-94V-0). Thermogravimetric analysis (TGA) revealed that the OMMT/MoO3 system lowered the initial decomposition temperature of the IFR, promoting early char formation. Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) confirmed that OMMT facilitated the early decomposition of ammonium polyphosphate (APP), increased char viscosity, and contributed to denser, more stable char structures. Scanning electron microscopy (SEM) and resistance monitoring demonstrated that suitable OMMT content promoted the formation of a continuous, compact char layer. However, excessive OMMT induced over-catalysis, generating excess gases during early combustion, which ruptured the char and formed pores, ultimately reducing flame retardancy.

Layered vanadium pentoxide (V2O5) is an ideal cathode material for aqueous zinc ion batteries (AZIBs) due to its adjustable structure, high specific capacity, and energy density. However, challenges such as narrow interlayer spacing and weak interlayer bonding hinder Zn2+ deintercalation kinetics and lead to poor cycling stability. This study explores the enhancement of vanadium pentoxide (V2O5) cathodes through the intercalation of bis(4nitrophenyl) phosphate (BNP), significantly expanding the interlayer spacing and improving electrochemical performance. The BNP-modified V2O5 (BVO) electrodes exhibit a remarkable specific capacity of 421 mAh g- 1 at 0.2 A g- 1, alongside excellent rate performance and cycling stability, with a retention rate of 100 % after 1000 cycles at 5 A g- 1. Comprehensive characterization confirms that BNP intercalation effectively enhances Zn2+ diffusion kinetics and structural stability. These findings highlight the potential of BNP-modified V2O5 cathodes for large-scale energy storage systems.

The hydrogel evaporator has shown great potential in solar-driven seawater desalination. However, hydrogels often suffer from heat loss due to their high-water content. Therefore, achieving a balance between energy input and water supply in hydrogels remains a challenge. Herein, Carbon Nanotube-Wrapped Polyacrylamide (CP) particles were introduced into sodium alginate (SA) to prepare CPSA hydrogels with tortuous channels. The hydrogel achieves a balance between photothermal conversion and water supply by enhancing its photothermal performance and increasing the water transport distance. Under 1.0 sun irradiation, the CPSA hydrogel exhibits an evaporation rate of 1.97 kg m-2 h-1. Additionally, the CPSA hydrogel demonstrates excellent photocatalytic ability for wastewater treatment, such as methylene blue (MB) degradation. Moreover, the tortuous microstructure imparts the CPSA hydrogel (thickness: 6 mm) with an outstanding electromagnetic interference shielding effectiveness of 81.1 dB, primarily through absorption. This work provides new insights into the development of hydrogels for water-energy balance management and high electromagnetic wave shielding applications.

Solar interfacial evaporation technology has been widely used in the field of water purification due to its low carbon emission and environmental friendliness. However, improving evaporation rates through the structural design of interfacial evaporators remains a challenge. Here, we prepared biodegradable aerogels based on cellulose nanofibers, chitosan, and citric acid, and subsequently prepared a solar evaporator with low enthalpy of evaporation by loading polypyrrole photothermal conversion agent on the aerogel. The evaporator is rich in hydrophilic groups such as hydroxyl, amine, and carboxyl groups, and the hydrogen bonding between them and water molecules changes the state of water adsorbed in the aerogel and reduces the evaporation enthalpy of the adsorbed water. The DSC results show that the evaporation enthalpy of water in the evaporator is as low as 1103 J g- 1. As a result, the solar evaporator has a high evaporation rate of 3.29 kg m- 2 h- 1 for pure water and 3.57 kg m- 2 h- 1 for 3.5 wt% brine with a solar efficiency of only 86.2 % (1.0 sunlight intensity). Moreover, the evaporator also has a better purification ability for dye wastewater. This research presents a simple and effective strategy for manufacturing high-performance degradable evaporators from biomass materials.