Rapid Self-healing Ability Research Articles

Self-healable epoxy/graphene oxide vitrimers and their recyclable glass fiber reinforced composites

Glass fiber-reinforced polymers (GFRPs) made from thermoset polymers have been widely used across various industries. However, these composites have significant drawbacks, including poor interfacial adhesion between the fiber and matrix, as well as a substantial contribution to waste and environmental pollution due to the challenges in recycling, reprocessing, and reuse. Herein, firstly graphene oxide (GO) was incorporated in vitrimer matrix to fabricate recyclable vitrimer nanocomposites with improved interfacial interaction, high thermal stability, low dielectric constant, fast stress relaxation as well as rapid self-healing ability. The nanocomposite with 0.2 wt% GO is optimized to achieve excellent remoulding (89% of flexural strength) and self-healing (60 min for a 48 μm scratch) properties due to dynamic disulfide bond exchange mechanism. Furthermore, epoxy/GO matrix was used to develop glass fiber reinforced composites via vacuum assisted resin infusion molding process (VARIM). The developed composites demonstrate tremendous mechanical strength (250 MPa), shape-memory, weldability, and degradable properties. Due to the rapid chemical degradation of epoxy vitrimer under mild conditions in the thiol (2-mercaptoethanol and 1-otanethiol), facilitated by thiol disulfide exchange reaction, glass fibers (GFs) can be effectively recycled. The performance of recycled glass fibers closely matches that of original fibers, exhibiting nearly identical woven structure and mechanical properties. The single yarn of recycled glass fibers can achieve tensile strength of 85% (1-octanethiol) and 72% (2-mercaptoethanol) of the original glass fibers, thus, the recycling of glass fibers would be highly advantageous in terms of achieving the sustainability goals.

Engineering Injectable Coassembled Hydrogel by Photothermal Driven Chitosan-Stabilized MoS2 Nanosheets for Infected Wound Healing.

The application of enzyme-like molybdenum disulfide (MoS2) in tissue repair was confronted with stable dispersion, solubilization, and biotoxicity. Here, the injectable self-healing hydrogel was successfully designed using a step-by-step coassembly of chitosan and MoS2. Polyphenolic chitosan as a "structural stabilizer" of MoS2 nanosheets reconstructed well-dispersed MoS2@CSH nanosheets, which improved the biocompatibility of traditional MoS2, and strengthened its photothermal conversion and enzyme-like activities, guaranteeing highly efficient radical scavenging and antimicrobial properties. Furthermore, the polyphenol chitosan was employed again as a "molecular cross-linking agent" to form the injectable NIR-responsive MoS2@CSH hydrogel by accelerating hydrogen-bond interaction among chitosan and the multicross-linking reaction among polyphenols. The rapid self-healing ability was conducive to wound closure and dynamic adaptability. An experimental study on infected wound healing demonstrated that MoS2@CSH hydrogel could substantially eradicate bacteria and accelerate the angiogenesis of infected wounds. The photothermal-driven coassembly of MoS2 and polycation provided an alternative strategy for infected wound healing.

Injectable self-healing alginate/PEG hydrogels cross-linked via thiol-Michael addition bonds for hemostasis and wound healing

In this study, an alginate/PEG hydrogel was developed via a thiol-Michael addition reaction between oxidized quinone of catechols on dopamine-grafted sodium alginate (SA-DA) and sulfhydryl groups of 4-arm polyethylene glycol tetra-thiol (4-arm PEG-SH) under mildly basic conditions. Through the formation of thiol-terminated catechol groups, the accompanying oxidized catechols are reduced, significantly strengthening the internal network structure of the hydrogel and improving tissue adhesion. Meanwhile, the hydrogels have excellent self-healing properties due to the dynamic non-covalent bonds between the groups. Adjustment of hydrogel properties by varying the mass ratio of two hydrogel precursors. Due to the high content of thiol-terminated catechol groups, the Gel 3 exhibited good tissue adhesion, rapid self-healing ability, and other multifunctions beneficial to wound healing, including killing of E. coli and S. aureus, rapid hemostasis and promoting migration of L929 cells. The full-thickness skin wound model shows that the hydrogel dressing significantly accelerated wound contraction, with increased granulation tissue thickness, collagen disposition, and enhanced vascularization, thus promoting wound healing. Therefore, the thiol-Michael addition reaction is an effective method for creating multifunctional hydrogels, and the injectable self-healing alginate/PEG hydrogels prepared in this way could be used in the biomedical area as wound healing dressing materials.

Robust multifunctional superhydrophobic and photocatalytic composites with all-weather self-healing ability

Superhydrophobic surfaces with rapid self-healing ability are ideal for long-life superhydrophobic materials. The micro-nano rough structure has great influence on the superhydrophobicity, and the micro-dissolution cotton fabric can realize the stable load of nanoparticles. In this regard, we prepared multifunctional fabrics with an all-weather self-healing superhydrophobic layer and photocatalytic self-cleaning properties by spraying TiN and TiO2 on micro-dissolution-treated polypyrrole/cotton fabrics. The results show that the modified fabrics maintain superhydrophobicity even in harsh environments (water contact angle (WCA) up to 160.0°, water sliding angle (WSA) as low as 3.9°), with excellent abrasion resistance and stability. Even after the fabric loses superhydrophobicity due to ion etching, the superhydrophobicity can be quickly restored by photothermal or electrothermal treatment in 13 min. At the same time, the prepared multifunctional fabrics have hydrophobic and oleophilic properties, and possess good oil-water separation efficiency (98.8 %). After being contaminated by oil, the WCA recovers from 135.0° to 160.0° via the photocatalytic property of the fabric. In addition, the fabrics exhibit excellent de-icing effects. This research provides new opportunities to extend the life of superhydrophobic textiles with all-weather self-healing properties.

Highly Sensitive, Degradable, and Rapid Self-Healing Hydrogel Sensor with Semi-Interpenetrating Network for Recognition of Micro-Expressions.

Flexible conductive hydrogels have revolutionized the lives and are widely applied in health monitoring and wearable electronics as a new generation of sensing materials. However, the inherent low mechanical strength, sensitivity, and lack of rapid self-healing capacity results in their short life, poor detection accuracy, and environmental pollution. Inspired by the molecular structure of bone and its chemical characteristics, a novel fully physically cross-linked conductive hydrogel is fabricated by the introduction of nanohydroxyapatite (HAp) as the dynamic junction points. In detail, the dynamically cross-linked network, including multiple physical interactions, provides it with rapid self-healing ability and excellent mechanical properties (elongation at break (>1200%), tensile strength (174kPa), and resilience (92.61%)). Besides, the ions (Cl-, Li+, Ca2+) that move freely within the system impart outstanding electrical conductivity (2.46±0.15 S m-1), high sensitivity (gauge factor, GF>8), good antifreeze (-40.2°C), and humidity properties. The assembled sensor can be employed to sensitively detect various large human motions and subtle changes in behavior (facial expressions, speech recognition). Meanwhile, the hydrogel sensor can also degrade in phosphate-buffered saline solution without causing any environmental pollution. Therefore, the designed hydrogels may become a promising candidate material in the future potential applications for smart wearable sensors and electronic skin.

Three-dimensional cross-linked network deep eutectic gel polymer electrolyte with the self-healing ability enable by hydrogen bonds and dynamic disulfide bonds

Solid polymer electrolytes (SPEs) are effective solutions for the development of high-performance and flexible lithium metal batteries (LMBs). However, the key problems of SPEs including low ionic conductivity and inability to repair damage have hindered their industrialization process. In this work, a three-dimensional (3D) cross-linked network gel polymer electrolyte (CNGPE) is designed. The addition of deep eutectic solvent (DES) improves the ionic conductivity of CNGPE. The hydrogen bonds and dynamic disulfide bonds in the 3D cross-linked network endow CNGPE rapid self-healing ability at ambient temperature. In addition, the addition of lithium difluoro(oxalato)borate (LiDFOB) and lithium nitrate (LiNO3) helps to form a stable solid electrolyte interface (SEI). Due to the ingenious design, the Li/CNGPE/Li symmetrical cell exhibits excellent interface stability and no short circuit occurs for more than 800 h. The assembled LiFePO4/CNGPE/Li cell exhibits a discharge specific capacity of 126 mAh g−1 after 960 cycles at 0.5C. This work has shown that the self-healing gel polymer electrolyte containing DES provides an effective and feasible method for the development of high-performance LMBs.

Radiation synthesis of covalently/non-covalently coupled all ionic liquid-based Ionogels with rapid self-healing, environmental tolerance for multifunctional ionic skin

As novel artificial ion-conducting materials with skin-like functionalities, Ionic skins (I-Skins) have attracted wide attention in the field of smart wearables. Nonetheless, the crucial hurdle of maintaining their properties in extreme conditions, such as cold, hot or long-term storage, persists. Herein, ionic liquid monomers, ionic liquid solvents, and ionic liquid cross-linkers are employed to facilitate covalently/non-covalently coupled all ionic liquid-based Ionogel for multimodal artificial I-skin through electron beam irradiation under mild conditions at the first time. Profiting from the covalently/non-covalently interactions in the Ionogel, the Ionogel has tunable mechanical properties, excellent environmental adaptability (−60 to 150 °C), long-term stability (90 days), fast response time (0.1 s), rapid self-healing ability (120 s recovery to 90 % of original), and favorable adhesion properties. Moreover, Ionogel sensors possess the remarkable capability to accurately perceive external stimuli, including strain, temperature, and humidity, similar to human skin, which can effectively monitor human movement behavior, as well as fluctuations in ambient temperature and humidity. It is expected that this all ionic liquid-based Ionogel sensor can fill the gap of I-Skin in extreme conditions and realize multifunctional flexible sensing, thus expanding more application scenarios.

Gelatin/carboxymethyl chitosan/aloe juice hydrogels with skin-like endurance and quick recovery: Preparation, characterization, and properties

Gelatin-based hydrogels have gained considerable attention due to their resemblance to the extracellular matrix and hydrophilic three-dimensional network structure. Apart from providing an air-permeable and moist environment, these hydrogels optimize the inflammatory microenvironment of the wounds. These properties make gelatin-based hydrogels highly competitive in the field of wound dressings. In this study, a series of composite hydrogels were prepared using gelatin (Gel) and carboxymethyl chitosan (CMCh) as primary materials, glutaraldehyde as a crosslinker, and aloe vera juice as an anti-inflammatory component. The properties of the hydrogel, including its rheological properties, microscopic structures, mechanical properties, swelling ratios, thermal stability, antibacterial properties, and biocompatibility, were investigated. The results demonstrate that the gelatin-based hydrogels exhibit good elasticity and rapid self-healing ability. The hydrogels exhibited slight shear behavior, which is advantageous for skin care applications. Furthermore, the inclusion of aloe vera juice into the hydrogel resulted in a dense structure, improved mechanical properties and enhanced swelling ratio. The Gel/CMCh/Aloe hydrogels tolerate a compressive strength similar to that of human skin. Moreover, the hydrogels displayed excellent cytocompatibility with HFF-1 cells, and exhibited antibacterial activity against E. coli and S. aureus. Lomefloxacin was used as a model drug to study the releasing behavior of the Gel/CMCh/aloe hydrogels. The results showed that the drug was released rapidly at the initial stage, and could continue to be released for 12 h, the maximum releasing rate exceeded 20 %. These findings suggest that the gelatin-based hydrogels hold great promise as effective wound dressings.

Self-healable, Tolerant Superaerophobic Coating for Improving Electrochemical Hydrogen Production.

Gas-evolving electrodes often suffer from the blocking of catalytic active sites-due to unwanted and unavoidable adhesion of generated gas bubbles, which elevates the overpotential for the electrochemical hydrogen evolution reaction (HER)- by raising the resistance of the electrode. Here, a catalyst-free and self-healable superaerophobic coating having ultra-low bubble adhesion is introduced for achieving significantly depleted overpotentials of 209 and 506mV at both low (50mAcm-2) and high (500mAcm-2) current densities, respectively, compared to a bare nickel-foam electrode. The optimized coating ensured an early detachment of the generated tiny (0.8±0.1mm) gas bubble-and thus, prevented the undesired rise in resistance of the coated electrode. The systematic association of physical (i.e., ionic interactions, H-bonding, etc.) cross-linkage, β-amino ester type covalent cross-linkage and reinforced halloysite nano clay enables the design of such functional material embedded with essential characteristics-including improved mechanical (toughness of 63.7kJm-3, and tensile modulus of 26kPa) property and chemical (extremes of pH (1 and 14), salinity, etc.) stability, rapid (<10min) self-healing ability (even at alkaline condition) and desired bubble-wettability (bubble contact angle of 158.2±0.2°) with ultralow force (4.2±0.4µN) of bubble adhesion.

Photothermal synergistic nitric oxide controlled release injectable self-healing adhesive hydrogel for biofilm eradication and wound healing.

The development of injectable self-healing adhesive hydrogel dressings with excellent bactericidal activity and wound healing ability is urgently in demand for combating biofilm infections. Herein, a multifunctional hydrogel (QP/QT-MB) with near-infrared (NIR) light-activated mild photothermal/gaseous antimicrobial activity was developed based on the dynamic reversible borate bonds and hydrogen bonds crosslinking between quaternization chitosan (QCS) derivatives alternatively containing phenylboronic acid and catechol-like moieties in conjunction with the in situ encapsulation of BNN6-loaded mesoporous polydopamine (MPDA@BNN6 NPs). Given the dynamic reversible cross-linking feature, the versatile hybrid hydrogel exhibited injectability, flexibility, and rapid self-healing ability. The numerous phenylboronic acid and catechol-like moieties on the QCS backbone confer the hydrogel with specific bacterial affinity, desirable tissue adhesion, and antioxidant stress ability that enhance bactericidal activity and facilitate the regeneration of infection wounds. Under NIR irradiation, the QP/QT-MB hydrogels exhibited a desirable mild photothermal effect and NIR-activity controllable NO delivery, combined with the endogenous contact antimicrobial activity of hydrogel, contributing jointly to induce dispersal of biofilms and disruption of the bacterial plasma membranes, ultimately leading to bacteria inactivation and biofilm elimination. In vivo experiments demonstrated that the fabricated QP/QT-MB hydrogel platform was capable of inducing efficient eradication of the S. aureus biofilm in a severely infected wound model and accelerating infected wound repair by promoting collagen deposition, angiogenesis, and suppressing inflammatory responses. Additionally, the QP/QT-MB hydrogel demonstrated excellent biocompatibility in vitro and in vivo. Collectively, the hydrogel (QP/QT-MB) reveals great potential application prospects as a promising alternative in the field of biofilm-associated infection treatment.

Ultra-robust, highly stretchable and ambient temperature rapid self-healing polyurethane/graphene elastomers enabled by multi-type hydrogen bonds

Elastomers with the strongest mechanical properties within 2 h of room-temperature self-healing were prepared based on a multi-type H-bond assembly, resolving the conflict between rapid self-healing ability and excellent mechanical strength in PUs.

Engineering a mussel-inspired hemostatic sealant with a strong tissue anchor as a first-aid tissue adhesive

During injury, achieving quick hemostasis, while maintaining adhesive performances on wet tissue and providing appropriate dynamical mechanical properties remain crucial clinical requests for the current tissue adhesives. Here, we design a double-crosslinking tissue adhesive with tunable degradation rate, adhesion strength, mechanical properties, and cell responses, using thiolated gelatin (Gel-SH) or gelatin and tannic acid (TA). We also investigate the role of different concentrations of gelatin (70 and 150 mg/ml), TA (7, 20, and 70 mg/ml), and crosslinkers (sodium periodate (11.3 and 16.8 mg/ml) and Fe3+ ions (1.7 and 4.8 mg/ml)) to provide a balance of covalent and noncovalent interactions leading to establish muscular tissue adhesive strength and superior hemostasis. Our findings reveal that the Gel-SH(gelatin)/TA adhesives have a range of swelling ability (300–700 %), compressive modulus (0.2–1.2 kPa), strength (0.1–0.8 kPa), and toughness (10–15 kJ/m3). In addition, Gel-SH/TA sample shows rapid self-healing ability and offers robust adhesiveness to wet cow skin and cardiac tissue (50–70 kPa) compared to others mainly owing to the improved cohesive strength originating from the range of chemical interaction within the adhesive network and abundant phenolic hydroxyl groups, surface water removal, and dynamic phenol-quinone balance at the tissue interfaces. Meanwhile, Gel-SH/TA adhesive also exhibits high hemocompatibility and hemostatic properties and appropriate in vitro biocompatibility. Notably, Gel-SH/TA adhesive could support attachment, viability and proliferation, of H9c2 cells. Overall, the multifunctional Gel-SH/TA adhesive hydrogel, owing to the range of molecular interactions opens a new opportunity for quick sealing hemostasis and wound healing and could potentially be harnessed for the development of clinically relevant tissue adhesives.

Dual-network conductive hydrogel with rapid self-healing ability and great fatigue resistance as strain sensor for human motion monitoring

As the classical soft materials, ionic conductive hydrogels have attracted considerable attention in the field of wearable strain sensors due to their unique stretchability, satisfactory conductivity, and good conformability. However, there remains a challenge in developing ionic conductive hydrogels that possess integrated mechanical strength, self-healing capability, and adhesion performance. Herein, a multifunctional dual-network poly(vinyl alcohol) (PVA)/borax (B)/sodium alginate (SA) ionic conductive hydrogel (PBS) was designed and constructed through a facile one-pot blending method with PVA and SA as the hydrogel matrix and borax as the cross-linker. The dynamic borate ester covalent bonds between PVA, SA and borax and hydrogen bonding between PVA and SA provided the energy dissipated center and endowed PBS hydrogel with favorable stretchability (∼950%), high toughness (122.21 kJ m−3), rapid self-healing ability, good fatigue resistance and robust adhesion performance. It can be assembled into strain sensor for its stable conductivity, high sensing sensitivity (gauge factor (GF) of 6.53), fast response time (280 ms) and excellent durability, which can be directly attached on body to accurately detect diverse human activity signals. This work is expected to provide new ideas for construction of high performance flexible sensor and to expand their application in electronic skin, wearable devices, and soft actuators.

Tannic Acid-Induced Gelation of Aqueous Suspensions of Cellulose Nanocrystals.

Nanocellulose hydrogels are a crucial category of soft biomaterials with versatile applications in tissue engineering, artificial extracellular matrices, and drug-delivery systems. In the present work, a simple and novel method, involving the self-assembly of cellulose nanocrystals (CNCs) induced by tannic acid (TA), was developed to construct a stable hydrogel (SH-CNC/TA) with oriented porous network structures. The gelation process is driven by the H-bonding interaction between the hydroxyl groups of CNCs and the catechol groups of TA, as substantiated by the atoms in molecules topology analysis and FTIR spectra. Interestingly, the assembled hydrogels exhibited a tunable hierarchical porous structure and mechanical moduli by varying the mass ratio of CNCs to TA. Furthermore, these hydrogels also demonstrate rapid self-healing ability due to the dynamic nature of the H-bond. Additionally, the structural stability of the SH-CNC/TA hydrogel could be further enhanced and adjusted by introducing coordination bonding between metal cations and TA. This H-bonding driven self-assembly method may promote the development of smart cellulose hydrogels with unique microstructures and properties for biomedical and other applications.

Chronological adhesive cardiac patch for synchronous mechanophysiological monitoring and electrocoupling therapy

With advances in tissue engineering and bioelectronics, flexible electronic hydrogels that allow conformal tissue integration, online precision diagnosis, and simultaneous tissue regeneration are expected to be the next-generation platform for the treatment of myocardial infarction. Here, we report a functionalized polyaniline-based chronological adhesive hydrogel patch (CAHP) that achieves spatiotemporally selective and conformal embedded integration with a moist and dynamic epicardium surface. Significantly, CAHP has high adhesion toughness, rapid self-healing ability, and enhanced electrochemical performance, facilitating sensitive sensing of cardiac mechanophysiology-mediated microdeformations and simultaneous improvement of myocardial fibrosis-induced electrophysiology. As a result, the flexible CAHP platform monitors diastolic-systolic amplitude and rhythm in the infarcted myocardium online while effectively inhibiting ventricular remodeling, promoting vascular regeneration, and improving electrophysiological function through electrocoupling therapy. Therefore, this diagnostic and therapeutic integration provides a promising monitorable treatment protocol for cardiac disease.

Fluoro-based organic small molecules as sliding crosslinkers for boosting stretchability and self-healability of polymers for hybrid human-motion sensing and energy harvesting

The development of highly capable soft electronic devices with exceptional attributes, including ultra-stretchability, robustness, and swift self-healing, is of great significance. However, achieving extreme stretchability at the same time as superior self-healing of energy generators remains a formidable challenge. Prevailing strategies aimed at enhancing stretchability and self-healing have predominantly focused on polymer backbone engineering. To address this challenge, we introduced fluoro-based organic small molecules (3N5F) into the polymer matrix, creating π-πF stacking and fluorine–hydrogen bonds with the polymer chains. The weak interactions formed between the sliding crosslinkers (3N5F molecules) and the polymer chains result in materials with ultra-stretchability (surpassing 20,000% strain without rupture) and rapid self-healing ability (recovering 100% of the mechanical properties within only 1 h). In the pursuit of an ultra-stretchable, self-healing, and conductive composite, we employed liquid metal or carbon black (CB) as conducting fillers for stretchable conductors. These conductors are utilized for motion and position sensing as well as for energy-harvesting triboelectric nanogenerators (TENGs). These show consistent performance, signifying a substantial advancement in the realm of next-generation self-powered electronics designed for the detection of human movement.

Fully bio-based thermosetting polyimine vitrimers with excellent adhesion, rapid self-healing, multi-recyclability and antibacterial ability

Traditional thermosetting materials cannot be degraded, recycled, or reprocessed once they attain their end-of-life causing environmental pollution. Using renewable feedstocks to develop covalent adaptive networks (CANs) based on dynamic covalent bonds can make up for the above shortcomings. The design of new polymeric materials using renewable feedstocks is consistent with the concept of sustainability practices. Herein, castor oil, cysteamine and vanillin are used as building blocks to construct fully bio-based thermosetting polyimine vitrimers through imination between cysteamine functionalized castor oil and divanillin. Owing to its unique structure containing flexible chains, aromatic hydrocarbon and imine bonds, polyimine vitrimers integrate fine mechanical properties, good thermal stability, excellent adhesion, rapid self-healing performance, degradability, recyclability and antibacterial ability. Specifically, the tensile strength of 5.21 MPa, lap-shear strength of 6.07 MPa on 304 stainless steels, self-healing within 30 min at 80 °C, and antibacterial rate against Staphylococcus aureus and Escherichia coli > 90% are observed for this fully bio-based polyimine vitrimers. Additionally, discarded materials can be recovered multiple times for repeated usage by thermo-compression reprocessing and solvent treatment. The original monomer DV is obtained by degradation under 1 M aqueous acetic acid solution with a recovery rate of 92.7%. Therefore, this work will provide a new research strategy for the application of multifunctional bio-based polymer materials, especially in adhesives.

Self-healable, mechanically durable and cold-resistant integrated supercapacitor enabled by dual metallic redox-mediated multiple cross-linking gel polymer electrolyte

Flexible supercapacitor is an important energy supply source for wearable electronic devices. Herein, an integrated supercapacitor with exceptional electrochemical performance is successfully constructed based on a novel dual redox-mediated double network (DN) gel polymer electrolyte (GPE). Thanks to the synergistic effect of DN structure and multiple physical interactions (hydrophobic association, hydrogen bond and ionic coordination), the polyacrylic acid/lauryl methacrylate/sodium carboxymethyl cellulose/H2SO4/CuSO4_FeSO4 GPE possesses exceptional mechanical properties and rapid self-healing ability. In addition to being ionic cross-linking agents, CuSO4_FeSO4 can also serve as carrier donors and anti-freezing agents, endowing the GPE with excellent conductivity (0.17 S/cm) and low temperature adaptability. The GPE-based integrated supercapacitor demonstrates an outstanding specific capacitance of 414.96 mF/cm2 and a high energy density of 84.21 μWh/cm2, benefiting from redox reactions of Cu2+/Cu+ and Fe2+/Fe3+ at the electrode/electrolyte interface. Due to the seamless gradient structure, the interfacial resistance is reduced and the relative slippage is overcome, resulting in splendid capacitance retention of the supercapacitor under various mechanical deformations. Moreover, the device demonstrates promising self-healing ability even at −20 °C. This work provides a novel strategy for designing and fabricating the supercapacitor with self-healing, arbitrary deformability and anti-freezing in next-generation electronic devices.

Eco-friendly intrinsic self-healing superhydrophobic polyurea/TiO2 composite coatings for underwater drag reduction and antifouling

With more and more exploration of the marine environment, a series of underwater monitoring equipment such as underwater vehicles are used more widely. Reducing the operation cost of underwater equipment and improving work efficiency have become the focus of attention. Superhydrophobic coatings have excellent applications in drag reduction, antifouling and other fields due to their unique surface wettability. This paper reports a superhydrophobic polyurea/TiO2 composite coating with rapid self-healing ability by simple sprinkling or spraying of modified TiO2 nanoparticles on the brushed polyurea coating. The modified TiO2 nanoparticles were driven to migrate to the surface of the coating by the synergistic self-healing effect of the disulfide and hydrogen bonds inside the polyurea, contributing to restoring the superhydrophobicity. This superhydrophobic polyurea/TiO2 composite coating possesses ~11.28 % drag reduction efficiency after being applied to underwater navigation, and it shows ~11.04 times higher water loading capacity than its weight. Moreover, this coating possesses excellent antifouling properties and chemical durability. This work provides new clues for future applications of drag reduction and pollution prevention of underwater exploration equipment.

Transparent self-healing luminescent elastomer with superior stretchability achieved via dynamic hard domain design

High mechanical performance versatile materials exhibiting rapid self-healing and luminescence ability are highly desired and present tremendous prospects in various fields. However, it is still a huge challenge to concurrently integrate all the above capacities into individual polymer materials, since these capabilities stem from different molecular mechanisms. Here, a dynamic hard domains strategy is reported for fabricating transparent luminescent self-healing elastomers featuring unprecedented stretchability (4333 ± 36%), high toughness (42.25 ± 0.19 MJ m−3) enabled by hydrogen-bonding (single and double) and lanthanide-bipyridine (Ln-Bpy) coordination interactions in the polymer chains. The dynamic rigid domains containing hydrogen-bonds constructed by urea and urethane groups and Ln-Bpy coordination also lead to a very dynamic system for fast self-healing at room temperature. Besides, excellent luminescence performance was obtained via the efficient energy transfer from the Bpy component to Ln3+ (Eu3+ and /or Tb3+). This strategy of dynamic rigid domains as building blocks applied in this study provides an alternative approach for preparing self-healing luminescence materials with superior stretchability and high toughness.