Dual-crosslinked Network Research Articles

Multifunctional Waterborne Polyurethane with Robustness, Adhesiveness, and Self-Healability Based on a Dual Cross-Linked Network Containing Multiple Dynamic Bonds

Multifunctional Waterborne Polyurethane with Robustness, Adhesiveness, and Self-Healability Based on a Dual Cross-Linked Network Containing Multiple Dynamic Bonds

Dual Cross-Linked Networks Reinforced Polyimide Foams with Outstanding Piezoelectric Properties and Heat Resistance Performance.

The application of traditional isocyanate-based polyimide (PI) foams is highly hindered due to limited flame retardancy, poor mechanical properties, and relatively single functionality. Herein, we propose an effective method to fabricate dual cross-linked polyimide/bismaleimide (PI-BMI) foams with outstanding heat resistance and enhanced mechanical properties by incorporating bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (ME-BMI) as the interpenetrating network. The results show that the prepared PI-BMI composite foams exhibit enhanced mechanical properties with lightweight characteristics (23-80 kg·m-3). When the ME-BMI loading reached 120 wt %, the tensile and compressive strength of PI-BMI composite foam can reach 1.9 and 7.8 MPa, which are 9.6 and 63.3 times higher than that of pure PI foam, respectively. In comparison with PIF-0, the 10% heat loss temperature (Td,10%) of PIF-90 improved by 156 °C. Moreover, the PI-BMI foam piezoelectric sensor containing fluorine groups presents a short response time (14.22 ms), high sensitivity (0.266 V/N), and outstanding stability (10 000 cycles). Besides, the sensor can accurately monitor human activity in different states. This work provides a promising strategy for designing multifunctional PI foams, making them suitable for applications in aerospace and microelectronics.

Chitosan-based composite featuring dual cross-linking networks for the removal of aqueous Cr(VI)

To avoid the environmental detriment caused by Cr(VI) waste, this study constructs a dual cross-linking network structure using sodium alginate (SA) and polyvinyl alcohol (PVA). Chitosan (CS) is further introduced through electrostatic attraction and hydrogen bonding and SA/PVA/CS (SPC) composite with porous structure is successfully prepared for the removal of Cr(VI) from wastewater. Batch adsorption experiments show that SPC has excellent adsorption capacity and practical usability with a broad pH applicability range. Under optimal adsorption conditions (pH = 2, t = 150 min, T = 35 °C, m/V = 2 g/L, C0 = 10 mg/L), the Cr(VI) removal rate of SPC achieves 89.2 %. Adsorption kinetics and isotherm models indicate that the adsorption process is primarily multi-layer and chemical adsorption. Additionally, FT-IR and XPS reveal that the adsorption mechanism of SPC for Cr(VI) involves a synergy of electrostatic attraction, reduction, ion exchange and complexation. Density functional theory (DFT) simulations also confirm the dominant role of CS in the Cr(VI) adsorption. In summary, SPC shows great potential for Cr(VI) wastewater treatment.

Dual cross-linked network of the active starch film by incorporating palmitic acid and geraniol: A comprehensive evaluation of the hydrophobic mechanism and antimicrobial activity

In this study, (3-Aminopropyl) triethoxysilane (APTES) was employed as a bridging agent to enhance the compatibility between the hydrophilic starch/pectin film and the hydrophobic palmitic acid (PA) coating through hydrogen bonding and chemical reactions. To address the insufficient antibacterial activity of starch films, geraniol was also incorporated. The intermolecular interactions among APTES, PA, and starch were confirmed using x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and hydrogen nuclear magnetic resonance spectroscopy (1H NMR). Notably, the inclusion of APTES and PA significantly increased the film's hydrophobicity, resulting in a water contact angle (WCA) of 95.12°, a water vapor permeability (WVP) of 2.08 × 10−10 g/(mm·s·Pa), and an oxygen permeability (OP) of 2.61 × 10−9 g·mm·mm−2·s−1. Molecular dynamics (MD) simulations revealed strong non-covalent interactions and exceptional compatibility between starch and PA. Furthermore, the integration of pectin and geraniol improved the mechanical strength and antimicrobial properties of the modified films compared to unmodified starch films. These environmentally friendly and biodegradable starch-based films present a promising option for sustainable packaging materials in food preservation.

Hierarchical H-bonding and metal coordination bonds enabled supramolecular dual networks for high-performance energy-dissipation

Natural organisms have superior material properties such as mechanical adaptability, impact protection, and self-healing to protect the body from complicated external environments, fascinating the development of functional supramolecular elastic materials with biomimetic protective features. Herein, a dual physically crosslinked supramolecular polyurethane (PU) network with strain-hardening effect is synthesized by incorporating hierarchical hydrogen bonds (H-bond) and metal coordination bonds into an elastomer matrix. A moderate content of quadruple H-bonds is critical for achieving a prominent toughness and a considerable strain-at-break owing to the strain hardening effect enabled by the hierarchical H-bonds. When the Zn-to-pyridine coordination bonds were introduced to the supramolecular PU, the strength, toughness, and energy dissipation properties were further enhanced attributing to the dual physical crosslinking networks. The dynamic dissociation and association of the sacrificial H-bonds and Zn-to-pyridine coordination bonds induced significant strain hardening effect and enabled tremendous energy absorption and self-healing properties. Besides, the supramolecular PU elastomers and their blends were foamed via scCO2 foaming to produce supramolecular foams containing dynamic bonds. The composite foam could effectively reduce the impact force from 6085 N to 373 N and achieve an outstanding energy absorption efficiency of 93.87% owing to the synergistic effect of porous structure and dual physically crosslinked networks. This work provides an innovative strategy for designing high-performance energy absorbing supramolecular elastomers and cushioning foams with reversible bonds.

A bio-based soy wood adhesive modified by dual-crosslinking strategy with excellent mechanical strength and water-resistance

Soy-based adhesives have garnered significant attention owing to their distinctive environmentally sustainable characteristics and low cost. However, they exhibit inadequate bonding strength and water-resistance, which can be attributed to the presence of polar groups in soy flours. Herein, a simple and eco-friendly dual-crosslinking strategy was proposed to manufacture a soy-based adhesive (SF/IO4/CA adhesive) with excellent mechanical properties and good water-resistance. Specifically, soy flours were treated with sodium periodate (NaIO4) for oxidization, which facilitated the soy flours' self-crosslinking process by converting carbohydrates into components having the cross-linking action (internal cross-linking agents). Then, incorporating the citric acid (CA) would promote to the carboxyl groups (-COOH) of CA to react with the hydrophilic hydroxyl groups (-OH) present in soy flours by esterification reaction. The findings demonstrated that a high-performance plywood using SF/IO4/CA adhesive was successfully produced, which shear strength of cold-water (20 °C for 24 h), hot-water (63 °C for 3 h), and boiling-water (93 °C for 3 h) reached 1.69 MPa, 1.68 MPa, 1.72 MPa, and 1.47 MPa, respectively. The soy-based adhesive has excellent mechanical strength and water-resistance due to its dual-crosslinking network system, which has significant promise for application use in the wood-based panels industry.

Withdrawal: Conductive Hydrogel Dressing With High Mechanical Strength for Joint Wound Healing.

Hydrogel wound dressing can accelerate angiogenesis to achieve rapid wound healing, but traditional hydrogel dressings are difficult to meet the repair of joint sites due to their low mechanical strength. Therefore, we constructed the gel system by designing the chemical-physical interpenetrating network structure to achieve high strength and high toughness of the hydrogel. The high-strength double-network hydrogels were synthesized by simple free radical polymerization and low-temperature physicochemical cross-linking in our experiments. The suspension was obtained by green reduction of graphene oxide with carboxymethyl chitosan, followed by the introduction of acrylamide (AM) to form a covalent cross-linked network, which was immersed in ferric chloride solution to form metal ligand bonds, and finally the chemical-physical dual cross-linked network hydrogel wound dressing was prepared. Here, reduced graphene oxide can enhance electrical conductivity and excellent near-infrared photothermal effect to the hydrogel. The cell viability of this novel wound dressing was above 90.0%, its hemolysis rate was below 2.0%, and the electrical conductivity could reach (6.89 ± 0.07 (mS/cm)). In addition, the stress-strain curve demonstrated that the double cross-linked network hydrogel could reach a stress of more than 0.8MPa at 82.0% strain, and the cyclic compression experiment shows that it can still recover its original shape after five times of repeated compression. This work can provide a reference for the exploitation of high mechanical strength hydrogel wound dressings with good electrical conductivity and near-infrared photothermal effect. This article is protected by copyright. All rights reserved.

Study the effect of different concentrations of polydopamine as a secure and bioactive crosslinker on dual crosslinking of oxidized alginate and gelatin wound dressings

Alginate hydrogels are commonly used in wound care due to their ability to maintain a moist environment, absorb fluids, and aid wound healing. However, their stability and mechanical properties can sometimes limit their effectiveness. This study explores a new approach by creating a dual network system of oxidized alginate and gelatin hydrogel crosslinked with polydopamine in a single step, with the goal of improving the mechanical properties of these hydrogels. The unique aspect of this research is the comprehensive examination of different polydopamine concentrations in dual crosslinking systems. First, alginate was modified with sodium periodate to create additional active groups on its backbone, and various polydopamine concentrations were then tested to assess their impact on the dual crosslinking network and hydrogel properties. The study involved a range of tests, including FTIR, H-NMR, SEM, gelation time, rheology, adhesion, antioxidant activity, swelling ratio, weight loss, drug release, and cell viability. The addition of polydopamine was found to enhance the crosslinking density (0.859 × 109 mol.cm−3). Additionally, the results indicated improvements in properties such as reduced weight loss, enhanced antioxidant and adhesive qualities, and better mechanical properties (2240 kPa). However, the optimal concentration of polydopamine must be determined to achieve the best properties for a wound dressing. Excessive polydopamine can increase the space between polymer chains, leading to a reduction in crosslinking density and storage modulus. Nevertheless, it can also increase the swelling ratio, degradation rate, pore size, porosity, antioxidant activity, and dopamine release. Therefore, identifying the optimal concentration for a functional hydrogel is crucial. Notably, the hydrogel containing 0.5 mg.mL−1 polydopamine exhibited outstanding cell viability (108 % on the third day), swelling capacity (480 %), storage modulus (2240 kPa), gelation time (3 min), antioxidant activity (42.27 %), and skin adherence (11 kPa), making it an optimal choice for advanced wound management. According to the findings, it is emphasized that the application of this particular hydrogel expedites wound healing, as indicated by wound closure and histological studies. AbbreviationsUnlabelled TableOALoxidized alginateGELgelatinPDApolydopamineEDCsodium meta periodate 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochlorideNHSN-hydroxysuccinimide

Temperature- and pH-induced dual-crosslinked methylcellulose/chitosan-gallol conjugate composite hydrogels with improved mechanical, tissue adhesive, and hemostatic properties

Gauze or bandages are commonly used to effectively control bleeding during trauma and surgery. However, conventional treatment methods can sometimes lead to secondary damages. In recent years, there has been increased interest in developing adhesive hemostatic hydrogels as a safer alternative for achieving hemostasis. Methylcellulose (MC) is a well-known thermo-sensitive polymer with excellent biocompatibility that is capable of forming a hydrogel through physical crosslinking owing to its inherent thermo-reversible properties. However, the poor mechanical properties of the MC hydrogel comprising a single crosslinked network (SN) limit its application as a hemostatic material. To address this issue, we incorporated a chitosan-gallol (CS-GA) conjugate, which has the ability to form chemical crosslinks through self-crosslinking reactions under specific pH conditions, into the MC hydrogel to reinforce the MC hydrogel network. The resulting MC/CS-GA hydrogel with a dual-crosslinked network (DN), involving both physical and chemical crosslinks, exhibited synergistic effects of the two types of crosslinks. Thus, compared with those of the SN hydrogel, the composite DN hydrogel exhibited significantly enhanced mechanical strength and tissue adhesive properties. Moreover, the DN hydrogel presented excellent biological activity in vitro. Additionally, in rat hepatic hemorrhage models, the DN hydrogel exhibited high hemostatic efficiency, showcasing its multifunctional capabilities.

Injectable pH- and Ultrasound-Responsive Dual-Crosslinked Dextran/Chitosan/TiO2 Nanocomposite Hydrogels for Antibacterial Applications.

Combining exogenous and endogenous antibacterial mechanisms has been demonstrated to enhance therapeutic efficacy significantly. This study constructs an innovative type of exogenous and endogenous antibacterial nanocomposite hydrogels with injectable dual-crosslinked networks and dual-stimuli responsiveness. The primary network establishes imine bonds between the functionalized dextran featuring norbornenes and aldehydes (NorAld-Dex) and the quaternized chitosan (QCS). The imine bonds provide self-healing, injectability, and pH-responsiveness to the hydrogel network. The secondary network is established by integrating thiolated mesoporous silica-coated titanium dioxide nanoparticles (TiO2@MS-SH) into the hydrogel network via an ultrasound-activated thiol-norbornene reaction with NorAld-Dex. The microstructures and properties of NorAld-Dex/QCS/TiO2@MS-SH hydrogels can be fine-tuned by adjusting the sonication time to increase the amount of thiol-norbornene crosslinks in the network. Effective antibacterial performance of NorAld-Dex/QCS/TiO2@MS-SH hydrogels at low pH has been demonstrated with the synergistic effect of the acid-induced dissociation of the hydrogel network, protonated QCS, and the reactive oxygen species (ROS) generated by TiO2@MS-SH nanoparticles under ultrasound irradiation. In summary, NorAld-Dex/QCS/TiO2@MS-SH nanocomposite hydrogel is an advanced dual stimuli-responsive antibacterial platform with customizable microstructures and properties, offering great potential for biomedical applications.

UV-curing 3D printing of high-performance, recyclable, biobased photosensitive resin enabled by dual-crosslinking networks

UV-curing 3D printing technologies based on vat photopolymerization have gained increasing interest in rapidly manufacturing high-quality custom-designed objects. However, they are still challenged by the non-renewability of photosensitive resins in future large-scale applications. Herein, a high-performance, recyclable, biobased carboxyl-terminated unsaturated polyester is developed from itaconic acid and bio-diols, which involves the formation of dual-crosslinking networks, i.e., covalent crosslinking of unsaturated double bonds and non-covalent coordination interaction between terminal carboxyl and ZnCl2. Dual-crosslinking networks greatly increase tensile strength from 31 to 43 MPa by 40 %. More importantly, taking advantage of the dynamic reversibility of coordination and thermally-activated transesterification by ZnCl2, the universal problem, i.e. the anisotropic mechanical property in 3D printing caused by printing layers, can be effectively solved, attributed to reversible rearrangement and reassociation between printing layers. Moreover, after the 3D printing products are pulverized into microparticles, the powders can be thermally compressed into new materials with a 70 % recovery in tensile strength. In addition, these powders can also be used as reinforcing fillers to enhance the virgin resin, the optimum tensile strength and elastic modulus further increase to 52 MPa and 1019 MPa by 40 % with 1 wt% dosages. Therefore, this study is a pioneering pathway for the concurrent achievement of good mechanical properties (52 MPa) and high biomass content (96 wt%) for UV-curable 3D printing photosensitive resin.

Engineering robust and transparent dual-crosslinked hydrogels for multimodal sensing without conductive additives

Conductive hydrogels are pivotal for the advancement of flexible sensors, electronic skin, and healthcare monitoring systems, facilitating transformative innovations. However, issues such as inadequate intrinsic compatibility, mismatched mechanical properties, and limited stability curtail their potential, resulting in compromised device efficacy and performance degradation. In this research, we engineered functional hydrogels featuring a dual-crosslinked network composed of (PA/PVA)-P(AM-AA) to address these challenges. This design eliminates the need for conductive additives, thereby enhancing intrinsic compatibility. Notably, the hydrogels exhibit exceptional mechanical properties, with high tensile strength (∼700 %), Young's modulus (∼5.33 MPa), increased strength (∼2.46 MPa) and toughness (∼6.59 MJ m−3). They also achieve a compressive strength of ∼7.33 MPa at 80 % maximal compressive strain and maintain about 89 % transparency. Moreover, flexible sensors derived from these hydrogels demonstrate enhanced multimodal sensing capabilities, including temperature, strain, and pressure detection, enabling precise monitoring of human movements. The integration of multiple hydrogels into a three-dimensional sensor array facilitates detailed spatial pressure distribution mapping. By strategically applying dual-crosslinked network engineering and eliminating conductive additives, we have streamlined the design and manufacturing of hydrogels to meet the rising demand for high-performance wearable sensors.

A Whole-Course-Repair System Based on Stimulus-Responsive Multifunctional Hydrogels for Myocardial Tissue Regeneration.

Myocardial infarction (MI) has emerged as the predominant cause of cardiovascular morbidity globally. The pathogenesis of MI unfolds as a progressive process encompassing three pivotal phases: inflammation, proliferation, and remodeling. Smart stimulus-responsive hydrogels have garnered considerable attention for their capacity to deliver therapeutic drugs precisely and controllably at the MI site. Here, a smart stimulus-responsive hydrogel with a dual-crosslinked network structure is designed, which enables the precise and controlled release of therapeutic drugs in different pathological stages for the treatment of MI. The hydrogel can rapidly release curcumin (Cur)in the inflammatory phase of MI to exert anti-apoptotic/anti-inflammatory effects. Recombinant humanized collagen type III (rhCol III) is loaded in the hydrogel and released as the hydrogel swelled/degraded during the proliferative phase to promote neovascularization. RepSox (a selective TGF-β inhibitor) releases from Pluronic F-127 grafted with aldehyde nanoparticles (PF127-CHO@RepSox NPs) in the remodeling phase to against fibrosis. The results in vitro and in vivo suggest that the hydrogel improves cardiac function and alleviates cardiac remodeling by suppressing inflammation and apoptosis, promoting neovascularization, and inhibiting myocardial fibrosis. A whole-course-repair system, leveraging stimulus-responsive multifunctional hydrogels, demonstrates notable effectiveness in enhancing post-MI cardiac function and facilitating the restoration of damaged myocardial tissue.

Coupled physicochemical dual-crosslinking Ti3C2Tx composite aerogels for the selective adsorption of gallium ions in acid fly ash leaching

Herein, in order to extract Ga3+ from acid fly ash leaching, we propose a functionalized Ti3C2Tx-based MXene composite aerogel adsorbent for Ga3+ adsorption. The prepared physicochemical dual-crosslinking network aerogel MPHG-40 possesses good Ga3+ adsorption performance (132.52 mg g−1) at the pH of 3 and Ga3+ initial concentration of 50 mg L−1 within 6 h. After five adsorption-desorption cycles, the material shows good mass retention and a 95.65 % retention of its initial adsorption capacity, compared to most reported adsorbents. The optimized adsorbent realized good selective adsorption of Ga3+ against Cu2+, Zn2+, Fe3+, and Al3+ in a simulated acid fly ash leaching with the selective coefficient of 8.63, 96.10, 4.49, and 28.30, respectively. The adsorption may comply with a combined mechanism of physical adsorption, electrostatic interactions, ion-exchange mechanism, and ligand chelation, dominated by chemical adsorption, as identified by theoretical calculations based on density functional theory and experimental data. The three-dimensional solid adsorbent constructed in this study provides a new strategy for selective adsorption of Ga3+, making it possible to be applied to solid waste utilization of fly ash.

Durable, colored and dual crosslinking networks constructed in Lyocell cellulose structure for high-quality greener textiles

Durable, colored and dual crosslinking networks constructed in Lyocell cellulose structure for high-quality greener textiles

Dynamic hydrogel–metal–organic framework system promotes bone regeneration in periodontitis through controlled drug delivery

Periodontitis is a prevalent chronic inflammatory disease, which leads to gradual degradation of alveolar bone. The challenges persist in achieving effective alveolar bone repair due to the unique bacterial microenvironment’s impact on immune responses. This study explores a novel approach utilizing Metal–Organic Frameworks (MOFs) (comprising magnesium and gallic acid) for promoting bone regeneration in periodontitis, which focuses on the physiological roles of magnesium ions in bone repair and gallic acid's antioxidant and immunomodulatory properties. However, the dynamic oral environment and irregular periodontal pockets pose challenges for sustained drug delivery. A smart responsive hydrogel system, integrating Carboxymethyl Chitosan (CMCS), Dextran (DEX) and 4-formylphenylboronic acid (4-FPBA) was designed to address this problem. The injectable self-healing hydrogel forms a dual-crosslinked network, incorporating the MOF and rendering its on-demand release sensitive to reactive oxygen species (ROS) levels and pH levels of periodontitis. We seek to analyze the hydrogel’s synergistic effects with MOFs in antibacterial functions, immunomodulation and promotion of bone regeneration in periodontitis. In vivo and in vitro experiment validated the system's efficacy in inhibiting inflammation-related genes and proteins expression to foster periodontal bone regeneration. This dynamic hydrogel system with MOFs, shows promise as a potential therapeutic avenue for addressing the challenges in bone regeneration in periodontitis.Graphical

Fabrication and properties of recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent polymer networks

The exploration of reprocessability and high-adhesion biomass polymer coatings is in line with the concept of green materials and is conducive to energy conservation and environmental protection. Here, a series of novel recyclable tung oil–based polymer coatings based on dual cross-linked dynamic covalent networks were reported. Tung oil polymerized maleic anhydride (TOA) was firstly prepared and further reacted with furfuryl alcohol. Then tung oil-polymerized maleic furanol ester (TOAFA) containing reactive conjugated double bond and carboxyl groups was prepared. FTIR and 1H NMR demonstrated the reactive monomer TOAFA was successfully synthesized. Then TOAFA was cross-linked with bismaleimide and different epoxy resins to fabricate target polymer networks based on dynamic Diels-Alder(D-A) bonds and dynamic transesterification. The shape memory, reprocessing, and mechanical and thermal stability of the copolymerized systems with different crosslinking states were investigated. The coating performances were characterized with solvent resistance, adhesion strength, hardness and glossiness tests. It was found that the dynamic D-A covalent bonds were perfectly combined with transesterification in the polymerization systems. The copolymerized systems possessed excellent thermal stability and mechanical properties. The rigid and flexible properties of the polymer networks can be controlled by adjusting the component weight ratios and the type of epoxy resin in the polymerization system. The rigid polymerization system had the highest tensile strength of 28 MPa, and its elongation at break was up to 57 % of the flexible polymerization system. Coating adhesion test showed the adhesion property reached level 1. The polymer coatings displayed excellent solvent corrosion resistance, and relative high gloss. The polymer networks also showed certain reprocessing performance and excellent shape memory effect.

High-strength, anti-fatigue, cellulose nanofiber reinforced polyvinyl alcohol based ionic conductive hydrogels for flexible strain/pressure sensors and triboelectric nanogenerators

Ionic conductive hydrogels (ICHs) have attracted great attention because of their excellent biocompatibility and structural similarity with biological tissues. However, it is still a huge challenge to prepare a high strength, conductivity and durability hydrogel-based flexible sensor with dual network structure through a simple and environmentally friendly method. In this work, a simple one-pot cycle freezing thawing method was proposed to prepare ICHs by dissolving polyvinyl alcohol (PVA) and ferric chloride (FeCl3) in cellulose nanofiber (CNF) aqueous dispersion. A dual cross-linked network was established in hydrogel through the hydrogen bonds and coordination bonds among PVA, CNF, and FeCl3. This structure endows the as-prepared hydrogel with high sensitivity (pressure sensitivity coefficient (S) = 5.326 in the pressure range of 0–5 kPa), wide response range (4511 kPa), excellent durability (over 3000 cycles), short response time (83 ms) and recovery time (117 ms), which can accurately detect various human activities in real time. Furthermore, the triboelectric nano-generator (TENG) made from PVA@CNF-FeCl3 hydrogel can not only supply power for commercial capacitors and LED lamps, but also be used as a self-powered sensor to detect human motion. This work provides a new approach for the development of the next generation of flexible wearable electronic devices.

Judiciously designed dual cross-linked networks for highly transparency, robustness and flexibility in liquid-repellent coatings

Highly transparent, durable, and flexible liquid-repellent coatings are urgently needed in the realm of transparent materials, such as car windows, optical lenses, solar panels, and flexible screen materials. However, it has been difficult to strike a balance between the robustness and flexibility of coatings constructed by a single cross-linked network design. To overcome the conundrum, this innovative approach effectively combines two distinct cross-linked networks with unique functions, thus overcoming the challenge. Through a tightly interwoven structure comprised of added crosslinking sites, the coating achieves improved liquid repellency (WCA>100°, OSA<10°), increased durability (withstands 2,000 cycles of cotton wear), enhanced flexibility (endures 5,000 cycles of bending with a bending radius of 1 mm), and maintains high transparency (over 98 % in the range of 410 nm to 760 nm). Additionally, the coating with remarkable adhesion can be applied to multiple substrates, enabling large-scale preparation and easy cycling coating, thus expanding its potential applications. The architecture of this fluoride-free dual cross-linked network not only advances liquid-repellent surfaces but also provides valuable insights for the development of eco-friendly materials in the future.

Recyclable and mechanically tough nanocellulose reinforced natural rubber composite conductive elastomers for flexible multifunctional sensor

The development of flexible wearable multifunctional electronics has gained great attention in the field of human motion monitoring. However, developing mechanically tough, highly stretchable, and recyclable composite conductive materials for application in multifunctional sensors remained great challenges. In this work, a mechanically tough, highly stretchable, and recyclable composite conductive elastomer with the dynamic physical-chemical dual-crosslinking network was fabricated by the combination of multiple hydrogen bonds and dynamic ester bonds. To prepare the proposed composite elastomers, the polyaniline-modified carboxylate cellulose nanocrystals (C-CNC@PANI) were used as both conductive filler to yield high conductivity of 15.08 mS/m, and mechanical reinforcement to construct the dynamic dual-crosslinking network with epoxidized natural rubber latex to realize the high mechanical strength (8.65 MPa) and toughness (29.57 MJ/m3). Meanwhile, the construction of dynamic dual-crosslinking network endowed the elastomer with satisfactory recyclability. Based on these features, the composite conductive elastomers were used as strain sensors, and electrode material for assembling flexible and recyclable self-powered sensors for monitoring human motions. Importantly, the composite conductive elastomers maintained reliable sensing and energy harvesting performance even after multiple recycling process. This study provides a new strategy for the preparation of recyclable, mechanically tough composite conductive materials for wearable sensors.