High strength and high toughness can be achieved in nanorestricted hydrogels through the movement of chain segments in highly entangled ionic clusters and polymer chains. Quantifying the relationship between the complex viscoelastic behavior and the mechanical properties generated by strong intermolecular interactions remains a challenge. In this work, inspired by the universal principle of the Boltzmann energy distribution and in combination with the upper convolution Maxwell (UCM) model, we established the physical constraint model controlled by the Boltzmann distribution (BDPhC). This model separately describes the viscous and elastic contributions of the constrained chain segments, yielding macroscopic mechanical properties that are in excellent agreement with the experimental results. Furthermore, the model reveals a scaling relationship between the Deborah number (De) and hysteresis in hydrogels and experimentally verifies that a near-perfect elasticity state would occur when De > 1. The model also effectively simulates the viscoelastic behavior of various reported high-strength hydrogels, demonstrating their broad applicability.

Polyampholyte (PA) hydrogels have attracted considerable attention due to their unique dynamic network structures and favorable biocompatibility. However, their low modulus severely limits applications in load-bearing aspects. Herein, we report ultrastiff PA nanocomposite hydrogels through the synergistic strategy of effective aggregation of hydrophilic silica (SiO2) nanoparticles and multi-bond networks. Specifically, a high content of SiO2 nanoparticles is first incorporated into a dynamic ionic PA network via in situ polymerization. The resulting hydrogel is subsequently dialyzed in a zirconium salt solution with strong coordination capability, achieving the ultrastiff nanocomposite hydrogel. In this strategy, the dynamic PA network infiltrated between the aggregated SiO2 nanoparticles enables effective particle aggregation, while the dynamic PA network, consisting of ionic and metal-coordination bonds, provides efficient energy dissipation, resulting in a synergistic reinforcement effect. The effects of dialysis time, concentration of zirconium salt, and particle content on the swelling and mechanical behaviors of the hydrogels are systematically investigated. The optimized nanocomposite hydrogel exhibits a Young’s modulus and a tensile strength as high as 87.9 ± 5.9 MPa and 7.9 ± 0.1 MPa, respectively, which are 976 and 8.8 times those of the original neat PA hydrogel. This work provides an effective strategy for designing hydrogels with ultrahigh mechanical performance.

Konjac glucomannan (KGM) is a natural polysaccharide with unique physicochemical properties. Due to its excellent gel-forming ability, film-forming capacity, biocompatibility, and biodegradability, KGM exhibits wide applications in diverse areas, such as food engineering, medicine, and environmental protection. However, neat KGM-based materials suffer from insufficient mechanical strength and poor environmental stability, necessitating composite material design to overcome these performance bottlenecks. This review systematically summarizes the recent advances in KGM-based functional composites, mainly focusing on the design strategies for high-performance KGM-based composites. Key approaches include molecular modification, multi-component compounding, and structural design, along with their mechanisms in regulating material properties. Additionally, the latest application progress in various fields is discussed. This review provides valuable insights for the development of high-performance KGM-based functional materials.

Echinoderms, such as sea cucumber, dynamically change their body size to environmental stimuli. By contrast, typical synthetic materials cannot reinvent their structures once formed. We propose a strategy for developing "self-extendability" polymeric materials that can be structurally tuned by repetitive mechanical stress stimulation. Polyion complex glycerol (PICG) hydrogels undergo self-extendability and mechanical consistency, and the materials substantially grow in deformation under repetitive loading through a diffusion of disentangled dense structure to sparse structure. This strategy is generalizable to other polymers and topologies. Additionally, the gel is able to adhere to 3D surface. These advancements make our gels ideal for e-skin substrate materials; they simultaneously offer extended performance and curved surface attachment. This work may open an avenue for the development of self-extendability materials for intelligent devices.

High strength and high toughness can be achieved in nanorestricted hydrogels through the movement of chain segments in highly entangled ionic clusters and polymer chains. Quantifying the relationship between the complex viscoelastic behavior and the mechanical properties generated by strong intermolecular interactions remains a challenge. In this work, inspired by the universal principle of the Boltzmann energy distribution and in combination with the upper convolution Maxwell (UCM) model, we established the physical constraint model controlled by the Boltzmann distribution (BDPhC). This model separately describes the viscous and elastic contributions of the constrained chain segments, yielding macroscopic mechanical properties that are in excellent agreement with the experimental results. Furthermore, the model reveals a scaling relationship between the Deborah number (De) and hysteresis in hydrogels and experimentally verifies that a near-perfect elasticity state would occur when De > 1. The model also effectively simulates the viscoelastic behavior of various reported high-strength hydrogels, demonstrating their broad applicability.

Conductive organogels, as a class of soft materials, have demonstrated great application potential in the field of flexible electronics. However, they often suffer from several drawbacks, including low transparency, poor mechanical properties, low sensitivity, and weak adhesion. In this work, a highly adhesive and stretchable double-network organogel is constructed by the interpenetration of a nanofiber network self-assembled from 1,3:2,4-dibenzylidene sorbitol (DBS) and tough polyacrylamide (PAM) chains in glycerol. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is incorporated to modulate the ionic conductivity of the gel, forming multiple ionic and intermolecular interactions within the gel network. The DBS/PAM-Li conductive organogel exhibits high and durable adhesion strength to various substrates, as well as good optical transparency (92% transmittance at a thickness of 1.45 mm). Furthermore, when assembled into a strain sensor, the DBS/PAM-Li organogel exhibits a high gauge factor of 8.72, a fast response time of 133 ms, and the capability to detect both small (with a low detection limit of 0.25% strain) and large deformations. This material can be used to monitor human motion, expanding the applications of flexible gel materials in the field of wearable electronics.

Polyethylene (PE) and polypropylene (PP) are thermodynamically immiscible, posing significant challenges for their recycling. Consequently, enhancing the compatibility of PE/PP blends has garnered increasing research interest in recent years. In this study, we transformed the physical mixture of PE and PP into a dynamically cross-linked single network of the two immiscible polymers by utilizing a lignin-based cluster as the interfacial compatibilizer and dynamic cross-linker. Through precise morphology control at the PE-PP interface, the originally brittle PE/PP blend was converted into a tough hybrid plastic with excellent photothermal conversion and ultraviolet (UV) shielding properties. At the optimal formulation, (PE60/PP40)-g-(L2-Zr-GMMA) achieved a tensile strength of 24.35 MPa, an elongation at break of 675.48%, and a Young's modulus of 279.11 MPa. The lignin-cluster-induced compatibilization process we report here may shed some light on addressing the major obstacle in sustainable PE and PP recycling.

Poly(butylene adipate-co-terephthalate) (PBAT) emerges as a prominent biodegradable resin aimed at supplanting petroleum-based counterparts to address plastic waste accumulation and environmental pollution concerns. Although enhancing the mechanical and heat-resistant characteristics of PBAT through moderate crosslinking is theoretically feasible, this approach inevitably complicates melt processing due to increased viscosity. Herein, we report the successful preparation of DCz-PBAT-g-(Dx-co-Sy) by incorporating a reversible boronic ester-based dynamic covalent network (DCN) into PBAT. This was achieved through grafting dioxaborolane monomethacrylate-co-styrene (Dx-co-Sy) copolymers onto the PBAT backbone using dicumyl peroxide (DCP) as the initiator, followed by dynamic crosslinking of the boron-oxygen (B-O) bonds on the grafts with 1,4-phenylenediboronic acid bis(propylene glycol) ester as the dynamic crosslinker. The optimal DC0.5-PBAT-g-(D3-co-S2) exhibited high tensile strength (32.34 MPa) and Young's modulus (58.47 MPa), representing increases of 45.9 % and 82.5 % compared to pristine PBAT, as well as excellent melt-processability. Further incorporation of long alkyl-linked dendritic montmorillonite (MMT) into DC0.5-PBAT-g-(D3-co-S2) significantly improved resistance to moisture and heat aging in the resulting DC-PBAT/MMT composite. This study introduces a novel strategy to enhance both mechanical performance and reprocessability of PBAT without compromising the processability, via a dynamic covalent network.

Myocardial infarction (MI)-induced heart failure is challenging because of poor cardiac self-repair and adverse remodeling. Hydrogel-based cardiac patches require integrated mechanical, electrical, adhesive, biocompatible, and biodegradable properties that remain difficult to achieve. Here, we report that a polysaccharide-based hydrogel patch, i-HEBioPEC, is realized by deliberately further dynamically interlocking an already highly entangled biopolyelectrolyte complex (HE-BioPEC) hydrogel network in situ via a chitosan and EDC/NHS coupling, respectively, inducing a physical bridging and chemical cross-linking synergistic interlocking mechanism. The patch enables on-demand cardiac repair through in situ tissue interlocking, exhibiting myocardium-like strain-stiffening, high toughness, fatigue resistance, tunable strength, and excellent biocompatibility, antimicrobial, and hemostatic performance. In MI rats, i-HEBioPEC effectively suppressed left ventricular dilation and adverse remodeling, improving the cardiac function. Notably, treated rats developed thinner, more mature scars with better functional recovery, indicating the active guidance of favorable repair. This work provides a new design strategy for multifunctional cardiac patches.

Polyampholyte (PA) hydrogels hold high potential in flexible electronics and soft smart materials. However, low fracture strength, poor fatigue resistance, and defect sensitivity are usually associated with single-polymer component PA hydrogels and largely limit their applications. Herein, we present a dynamically highly entangled (HE) strong and tough PA hydrogel of single-polymer composition and favorable biomimetic strain-hardening characteristic, HE-PA, via a simple two-stage consecutive photopolymerization process, through which additional polymer chains formed in the second stage mechanically interlock and densely entangle in situ with the PA network of the same polymer composition formed in the first. Such HE-PA hydrogels possessed excellent mechanical properties, typically high breaking strength (2.3 MPa) and fatigue resistance (Delta c approximate to 0.2 mm, after 1000 repeated tensile cycles), low defect sensitivity (& Gcy; =11.4 kJ/m2), and exceptional strain hardening capacity of 19.3. Furthermore, the HE-PA hydrogel exhibited good strain responsiveness (Gauge Factor(GF) = 5.73 in 400%-600% strain range) and flexoelectric coefficient (1650.1 mu C/m), both in favor of its applications as soft actuators and sensors and energy harvesting smart materials. The simple and feasible strategy presented here may provide some insight into the preparation of high-performance PA hydrogels for flexible electronic applications.

Polyvinylidene difluoride (PVDF) microfiltration membranes hold significant potential for oily wastewater treatment due to their exceptional mechanical and chemical stability. However, PVDF's inherent hydrophobicity leads to severe fouling, limiting its use in heavily contaminated waters, and particularly hindering continuous operation in pollutant-rich environments. Thus, modifying PVDF to establish robust hydrophilicity is urgently needed for sustainable, multifaceted antifouling purposes. Inspired by organic-inorganic bridges, we developed a phase-controlled strategy to fabricate an Al3+-crosslinked ionic polymer-PVDF membrane. This was achieved by integrating favorable bridging structures into the PVDF matrix. Specifically, 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) and diethanolamine (DEA), polymerized in situ in the casting solution, undergo Al3+-OH and Al3+-SO3- coordination-driven crosslinking during the phase separation process. This process enabled simultaneous Al3+-polymer coordination, resulting in a stable organic-inorganic bridging network in the porous membrane. PVDF/P(AMPS-DEA)@Al3+ exhibited superhydrophilicity (0 degrees water contact angle in 20 s) and high pure water flux (2600 Lm(-2)h(-1) under 0.1 bar) at room temperature (25 degrees C). Additionally, the membranes demonstrated robust and sustained performance in separating oily wastewater (with mineral oil used as model foulant) (864 Lm(-2)h(-1) high flux and > 98.5 % oil rejection rate after three oil-water separation cycles). Lastly, PVDF/P(AMPS-DEA)@Al3+ exhibited remarkable resistance to multiple types of biofouling, including bovine serum albumin (BSA) protein, B. Subtilis and E. Coli bacteria, and diatoms. This work introduces a novel organic-inorganic bridging strategy for PVDF modification, offering a robust approach toward scalable.

Flexible supercapacitors (FSCs) have made remarkable progress in recent years as important wearable electronic devices; however, it still remains a challenge to attain high power and energy density in extreme environments. Herein, we present our design and assembly of an all-hydrogel FSC, (PIC-ACP/PANI)|PA-H3PO4|(PIC-ACP/ PANI), by integrating antifreezing polyampholyte (PA) and highly conductive self-healing polyion composite (PIC) hydrogels. The P(NaSS-co-MPTC) PA hydrogel electrolyte was constructed with a hydrophilic crosslinker ethylene glycol diacrylate urethane (BAGU) and phosphoric acid (H3PO4) doping, while the poly(sodium p-styrenesulfonate)/poly(3-methacryloylamino propyl-trimethylammonium chloride) (PNaSS/PMPTC) PIC hydrogel electrode was fabricated by kneading-hot pressing a precursor dough of PNaSS and PMPTC hydrogels (fabricated separately prior) doped with activated carbon particles (ACPs) and polyaniline (PANI) in large quantity (up to 30 wt%). The typical all-hydrogel FSC device of 15%/15% ACP/PANI wt% ratio exhibited strong interfacial adhesion (798.72 N m(-1)) and high electrochemical performance (areal capacitance of 1190 mF cm(-2) at 1 mA cm(-2) and energy density of 159 mu Wh cm(-2) at 1005 mu W cm(-2)) and stability (similar to 90% and 82% areal capacitance retentions at 180 degrees bending angle and after 2000 charge/discharge cycles at 5 mA cm(-2), respectively, and remained as high as 316.5 mF cm(-2) at-30 degrees C). The easy and simple fabrication and assembly strategy of allhydrogel FSCs we demonstrate here may provide a new and economic alternative solution to addressing the demand of high-performance and frost-resistance of wearable energy storage devices.

The antifouling capabilities of zwitterionic hydrogels have been well established, yet, drawbacks such as single antifouling performance and osmotic pressure-driven swelling in water, which lead to poor mechanical properties and low bonding strength, respectively, remain obstacles to practical applications. In this work, silanemodified polyampholyte (S-PA)-based hydrogel coatings with high adhesive strength and multi-scale antifouling ability were prepared by introducing silane onto the hydrogel surfaces. The resulting S-PA hydrogel coatings exhibited as high as 1980 J m- 2 adhesion, due to the covalent bonding between the vinyl groups in PA and silanols in silane molecules. Furthermore, the S-PA hydrogel coatings demonstrated good protein adsorption resistance (the protein adsorption capacity of bovine serum protein was 5 mg g- 1) and bacteriostatic ability, which endows the coating's multi-scale antifouling effect together with its excellent anti-diatom adhesion property (the adhesion area of navicular on S-PA hydrogel was as low as 7.43 mm2). The high adhesive strength and multi-scale antifouling ability of the S-PA hydrogel coatings presented in this work may provide a new route toward marine antifouling strategies.

Polytetrafluorethylene (PTFE) is the preferred material for highly polluted wastewater treatment. Hydrophilic modification of the PTFE hollow fiber membrane can further enhance its filtration performance and durability. Yet, it still remains a challenge to construct a robust hydrophilic coating on the PTFE surface. Here we report a surface engineering strategy of in situ coating a PTFE hollow fiber membrane with poly(vinyl alcohol) (PVA) and polyion complex (PIC) double-layer (DL) hydrogels. The first PVA hydrogel layer was covalently bonded to N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane (AEAPTS)-grafted PTFE via a glutaraldehyde (GA)-induced Schiff base reaction and aldol condensation, respectively, while the second PIC hydrogel layer was strongly anchored on PVA through hydrogen bonding and topological entanglements. The resulting PVA/PIC DL hydrogel coating exhibited favorable strength and chemical resistance. Moreover, the double-defense mechanism provided by the hydration layer and polyzwitterionic brushes endowed the membrane with durable microfiltration and antifouling performances by effectively repelling various types of pollutants.

The modification of polypropylene (PP) to achieve increased hydrophobicity while maintaining structural integrity is an important yet challenging task. In this work, by introducing a hydrophobically modified inorganic filler (silica (SiO2) modified with perfluorooctyltriethoxysilane (FOTS)), m-SiO2/PP composites are produced via melt blending, then pressing of composites into sheets with different substrates. Measurement of the contact angle gives that when pressed with polytetrafluoroethylene (PTFE) film substrate, the water contact angle of the composite with 20 wt.% m-SiO2 can reach 140 degrees, which is 44% higher than that of pure PP (97 degrees).By scanning electron microscopy and micro-infrared analysis, when the composites are pressed into sheets with PTFE substrates, m-SiO2 migrates to its pressed side. This is due to in PTFE, hydrogen atoms in the polyethylene structure are replaced by fluorine atoms, thereby forming a "fluorine generation" protective layer over the carbon-carbon skeleton. Hence, the fact that in PP composites with PTFE platens, fluorosilane chain-encapsulated PTFE sheets and m-SiO2 are attracted to each other due to the presence of very stable C & horbar;F bonds, which have a very low surface energy. This material has self-cleaning properties and is expected to be widely used for protection against dust and oil.

Bioadhesive hydrogels of favorable tribological attributes have attracted intensive attention for their potential usage due to the large benefits they can bring to surgical critical care. We report an all-natural polymer-based and bilayer-integrated asymmetrical Janus hydrogel bioadhesive patch for efficient myocardial infarction (MI) repair. We developed a low-friction polyelectrolyte composite biohydrogel (Bio-PEC hydrogel), CA, using naturally occurring cationic chitosan quaternary ammonium salt (HACC) and anionic sodium hyaluronate (HA). We further developed a high-adhesion Bio-PEC hydrogel, TA@CA, by incorporating tannic acid (TA). Ultimately, we integrated them into a bilayer asymmetrical Janus hydrogel bioadhesive, CA|TA@CA, which exhibited excellent bulk mechanical properties and favorable one-sided adequate adhesion to myocardial tissue (fracture strength 0.98 MPa, fracture strain 330%, and interfacial toughness 50.87 J/m2). Additionally, the in vivo myocardial repair surgery using the CA|TA@CA Janus hydrogel has been shown to inhibit ventricular remodeling more effectively. Such CA|TA@CA Janus hydrogel bioadhesives may have high potential as medical patches for MI repair.

Soft biotissues (e.g., skin) are usually tough, rapidly mechanoresponsive and signal-sensitive. However, most synthetic materials lack these combined features. Here we develop skin-like soft yet robust hydrogels via a strategy of pre-stretch induced multiple bonds-network alignment. In the design, the gels are fabricated by introducing metal-coordination bonds in a bicontinuous multiphase ionic polyampholyte network through a secondary equilibrium approach accompanied with pre-stretching. Based on this approach, the aligned polymer chains are effectively locked, while the formed hard phase provides elastic entropy to make the aligned chains slightly contract back, achieving the robust and rapidly mechanoresponsive gels. The aligned chains could also serve as swimming lane-like ionic nanochannels to provide skin-like rapid electronic sensitivity. The effects of the pre-stretch ratio and the concentration of FeCl3 solution are systematically investigated. The results indicate that both the parameters could affect the formation of the aligned microstructures, resulting in the different mechanical enhancements and response behaviors. The optimized hydrogels possess significantly enhanced mechanical properties and rapid mechanical and electronic responses. This study not only provides a method for designing soft yet robust hydrogels with rapid mechanical and electronic responses for wearable electronics, but also give some insights on the mechanics of aligned polymeric networks.

Despite similar hydrocarbon compositions, polyethylene (PE) and polypropylene (PP) are mutually immiscible, posing challenges to their recycling. Consequently, significant research efforts have been made on PE/PP compatibilization. In this study, we transformed physical blends of PE and PP into dynamic covalent polymer networks by taking advantage of reversible boronate ester bonds. The dynamically cross-linked network "welds" PE and PP phases together, enabling PE-PP interfacial compatibilization through morphological control and converting the otherwise brittle PE and PP blend into a tough PE/PP hybrid plastic.

Polyampholyte (PA) hydrogels, composed of charged hydrophilic networks with both positive and negative groups, have attracted great attention due to the unique structure and excellent antifouling properties. Yet, the superhydrophilicity usually makes non‐neutral PA ( n ‐PA) gels highly swollen and mechanically very weak in aqueous environments, severely limiting their applications. Herein metal‐coordination bonds are designed to introduce to synergistically toughen n ‐PA hydrogels with ionic bonds via a secondary equilibrium strategy. In the design, as‐prepared n ‐PA gels are dialyzed in metal‐ion solutions and deionized water in sequence to achieve the tough gels. Through this strategy, the weak n ‐PA gels can be significantly toughened by the synergy of ionic and metal‐coordination bonds. A systematic study indicates that both the molar ratio of oppositely charged monomers and the metal‐ion concentration affect the mechanical enhancements clearly. The universality of the proposed strategy is further proved by selecting different gel systems and multivalent metal ions. Notably, low metal‐ion concentrations (≤0.1 m ) of dialysis solutions can enable synergistic toughening. Theoretical models are also adopted to disclose the toughening mechanism. This work not only expands the understanding on the fabrication of strong and tough PA hydrogels but also provides some insights for PA gels in electrolyte solutions.