Hydrogen Bond Dynamics Research Articles

Epigallocatechin gallate-loaded pH-responsive dressing with effective antioxidant, antibacterial and anti-biofilm properties for wound healing

High blood glucose levels, excessive production of reactive oxygen species (ROS), unbalanced inflammatory responses and impaired angiogenesis render chronic wounds more likely to be colonized by bacteria which can form biofilms, leading to recurrent infections and prolonging disunion. The pH-responsive fibers of poly (vinyl alcohol) (PVA)/poly (acrylic acid) (PAA) -epigallocatechin gallate (EGCG) have been constructed. The fibers were able to swell (pH > 7.4) /shrink (pH < 6.5) reversibly with changes in wound pH, controlling the rate of drug release and thus dynamically modulating the complex inflammatory environment of the wound. At the phase of bacterial infection (pH = 7–9), the polycarboxylic acid groups in the network ionized, and the dynamic hydrogen bond between EGCG and PVA and PAA was broke, triggered an increased release of EGCG (87.4 %). Thereafter, the EGCG cleared excess ROS (greater than80.0 %) from the wound and showed significant antibacterial activity against S. aureus (98 %) and Pseudomonas aeruginosa (96.7 %), inhibited biofilm formation (74 %). At the proliferative phase, the wound switched to acidic (pH ∼ 6.5). Fibers swelled less and tended to shrink. The release of EGCG was slowed down (45.8 %) to promote macrophage polarization and remodel the wound microenvironment.

Catalyst-free, highly sensitive and adjustable photo-responsive azobenzene liquid crystal elastomers based on dynamic multiple hydrogen bond

Photo-responsive liquid crystal elastomers (LCEs) containing azobenzene components have received great attention and are in great demand gap for the development of smart materials. Herein, we have prepared a novel azobenzene photo-responsive liquid crystal elastomer (HAzo-LCEs) through simultaneously introducing azobenzene molecules and 2-ureido-4-pyrimidone (UPy) units into main chain of polyurethane molecule. Utilizing polyurethane system into this HAzo-LCEs has a trade-off between the exceptional mechanical performance and quick response. Especially, the transformation of photo-responsive HAzo-LCEs from polydomain to monodomain liquid crystal structures has been achieved under the catalyst-free and low temperature conditions by exploiting the dynamic nature of multiple hydrogen bond between UPy units. This synthetic method breaks the dilemma that the conventional photo-responsive LCEs require the preparation of monodomain liquid crystal structures at high temperatures or with the help of a large number of catalysts. Importantly, the HAzo-LCEs sample can bend rapidly in response to the UV light, and the maximum bending angle of the sample could reach 144°. Intriguingly, the blended HAzo-LCEs sample can rapidly straighten and finally extended under green light, showing the high sensitivity and flexible adjustability. It is valuable to integrating the high sensitivity, flexible adjustability and complete reversibility into one photo-responsive elastomers of this HAzo-LCEs. Furthermore, the multiple hydrogen bonds from UPy units allows the HAzo-LCEs to regulate its dynamics and stability by increasing the number and binding sites through the advantages of adjustable strength, high selectivity and abundant formation modes, providing great design and application scope for photo-responsive liquid crystal elastomers. This design route of non-toxic PU-based HAzo-LCEs provides a novel approach to broaden photo-responsive LCEs application in sensor and actuator.

Rapid self-healing, self-adhesive, anti-freezing, moisturizing, antibacterial and multi-stimuli-responsive PVA/starch/tea polyphenol-based composite conductive organohydrogel as flexible strain sensor

• A novel PVA/starch/tea polyphenol-based conductive organohydrogel is fabricated. • Organohydrogel contains dynamic borate ester bonds and reversible multiple hydrogen bonds. • Organohydrogel features its remarkable self-healing and self-adhesive properties in the air, underwater and at low temperature. • Organohydrogel exhibits anti-freezing, moisturizing, antibacterial and pH/sugar-responsive properties. • Organohydrogel as strain sensor can accurately monitor various human motions and vital signs. The complexity of application environment stimulates the development of wearable devices based on functional hydrogels. Among all the promising performances, self-healing and self-adhesion properties are ideal for hydrogel sensors, which can guarantee good accuracy, comfort and long service life. However, it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments (in the air, underwater and at low temperatures). Herein, a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol (PVA)/tea polyphenol (TP) with borax, and multiple hydrogen-bond interactions among PVA, starch, TP and ethylene glycol (EG). Silver nanoparticles (AgNPs), reduced and stabilized by TP, and MWCNTs (multi-walled carbon nanotubes) were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity, respectively. The organohydrogel possessed rapid self-healing (HE (self-healing efficiency) = 96.07% in 90 s, both in the air and underwater, also at -20 °C), considerable self-adhesion (both in the air and underwater, also at -20 °C), remarkable stretchability (814% of elongation), anti-freezing (-20 °C) and moisture-retention abilities, antibacterial activity, sensitive pH/sugar-responsiveness, and plasticity. The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions (e.g. finger/wrist/elbow bending, walking, etc.), but also accurately capture subtle motion changes (e.g. breathing, chewing, swallowing, speaking, smiling and frowning). Moreover, the self-healed organohydrogel sensor also exhibited almost invariable mechanical, electrical and sensing behaviors. This work demonstrates a feasible strategy to construct multifunctional starch-based organohydrogels, and promotes their efficient, stable and eco-friendly application as flexible wearable devices.

Facile Hydrogels of AIEgens Applied as Reusable Sensors for In Situ and Early Warning of Metallic Corrosion

Early detection of metallic corrosion is one considerable method to reduce imperceptible disasters nowadays. Fluorescent coatings with high sensitivity and long lifetimes for use in the early detection of metallic corrosion are in high demand, but they are presently difficult to prepare. Inspired by the chameleon's skin, which is capable of switching its color in different atmospheres sensitively and reversibly, we proposed herein a facile and universal all-in-one strategy of combining the fluorescent sensitivity and dynamic hydrogen bonds in a hydrogel to develop a reusable corrosion detection tape to cover metal surfaces. The fluorescent hydrogel tape was constructed using free radical copolymerization of monomers [hydroxyethyl methylacrylate (HEMA) and tetraphenylethene derivatives (TPEPy)]. Due to the aggregation-induced emission (AIE) behavior of TPEPy, the poly(HEMA-co-TPEPy) hydrogel is capable of monitoring the traces of corrosion via the release of ferric ions with a concentration as low as 10-5 M. Moreover, due to the dynamic hydrogen bonds of hydroxyethyl groups in hydrogel networks, the fluorescent hydrogel tape exhibited good adhesion and well reusability for over 10 applications to effectively warn against early corrosion of stainless steel. This non-destructive and reversible method of early corrosion detection can provide valuable signals when maintenance is needed before the metal suffers serious damage.

An Autonomously Self‐Healing Silicone Polyurea Waterproof Coating for Combustible Cartridge Cases

AbstractNitrocellulose‐based combustible cartridge case (NC‐3C) is highly hygroscopic, which greatly limits its broader application. The effective strategy for NC‐3Cs to prevent moisture is the endowment of waterproof coatings. However, the traditional waterproof coatings for NC‐3Cs cannot self‐heal the inevitable mechanical microcracks suffered during handling and storage, which often gives moisture much more opportunities to destroy the internals. Therefore, it is necessary to develop a self‐healing waterproof coating for the protection of NC‐3Cs. Herein, a smart self‐healing silicone polyurea (SPU) elastomer based on dynamic reversible hydrogen bonds is designed as a waterproof coating for NC‐3Cs. The SPU elastomer shows an outstanding self‐healing efficiency of 99.06 % after 12‐hour self‐healing at room temperature. And it also can self‐heal its damages even when the ambient temperatures rise to 50 °C or drop to −18 °C. Moreover, the SPU‐coated NC‐3C can also self‐heal its microcracks in time after being scratched and obtains extremely low water absorptions (&lt;0.20 %) after 24‐hour soaking, exhibiting good waterproof performance. Endowing the waterproof coating with self‐healing ability is a promising design strategy to repair the coating microcracks and improve the environmental adaptability of NC‐3C during handling and storage. This work pioneers a new design of self‐healing waterproof coating for NC‐3Cs, and it has a positive guiding significance to expend broader application of NC‐3C.

Hydrogen Bond Dynamics and Phase Transitions of Water inside Carbon Nanotubes.

Water dynamics in nanochannels are altered by confinement, particularly in small carbon nanotubes (CNTs). However, the mechanisms behind these effects remain unclear. To address these issues, we carried out extensive molecular dynamics (MD) simulations to investigate the structure and dynamics of water inside CNTs of different sizes (length of 20 nm and diameters vary from 0.8 nm to 5.0 nm) at different temperatures (from 200 K to 420 K). The radial density profile of water inside CNTs shows a single peak near the CNT walls for small nanotubes. For CNTs with larger sizes, water molecules are arranged into coaxial tubular sheets, the number of which increases with the CNT size. Subdiffusive behavior is observed for ultranarrow CNTs with diameters of 0.8 nm and 1 nm. As the size of CNTs increases, Fickian diffusion becomes evident. The hydrogen bond correlation function of water inside CNT decays slower than in bulk water, and the decay rate decreases as we increase the diameter of the CNTs. In large CNTs, the hydrogen bond lifetime of the innermost layer is shorter than the other layers and depends on temperature. Additional analysis of our results reveals that water molecules along the CNT axis show a non-Arrhenius to Arrhenius diffusion crossover. In general, the diffusion transition temperature is higher than that of bulk water, but it depends on the size of the CNT.

Self-Healable, Recyclable, and Reprocessable Poly(urethane–urea) Elastomers with Tunable Mechanical Properties Constructed by Incorporating Triple Dynamic Bonds

Elastomers that are self-healable, recyclable, reprocessable, and customizable in mechanical properties are desired for numerous industries but remain challenging to achieve. Herein, we develop novel poly(urethane–urea) (PUU) elastomers involving triple dynamic bonds in a convenient and efficient manner. Briefly, a prepolymer based on polyetheramine terminated by asymmetric alicyclic diisocyanate was synthesized and chain-extended with two diamines to generate a PUU elastomer containing dynamic hydrogen bonds (H bonds) and disulfide bonds, followed by incorporation with Zn2+ ions for Zn2+–urea coordination. The coordination bonds were proved to augment the microphase separation leading the hard segment domains to be homogeneously distributed in the soft phase and serve as nanoscale reinforcements for the simultaneous improvement of the mechanical modulus, strength, and toughness, which were facilely tunable by varying the zinc content. In the meantime, self-healing could be achieved at room temperature or no higher than 40 °C owing to the dynamic exchangeable bonds. Impressively, the elastomers can be reprocessed by hot pressing and recycled by solvent dissolution. This work, combining the macromolecular structure design with metal–urea coordination bonds, adds a new strategy to the toolbox of constructing elastomers with tunable and advanced performances.

Interplay of conformational relaxation and hydrogen bond dynamics in the excited states of fluorescent Schiff base anions.

Time resolved fluorescence spectroscopic investigation of four Schiff base anions has established that their excited state dynamics is governed by several solvent properties: polarity, viscosity and hydrogen bond donating ability. With viscous protic solvents like glycerol, fluorescence lifetimes of anions have been found to be markedly longer than those in ethanol, implying that conformational relaxation of molecules plays a key role in their nonradiative relaxation. Surprisingly, the lifetimes in less viscous aprotic solvents, like acetonitrile, are found to be even longer. The only plausible rationalization of this observation is in the light of hydrogen bond-assisted nonradiative phenomena that are operative in protic solvents. This contention draws support from a time evolution of the emission in the red end of the spectrum in low to moderately hydrogen bond donating protic solvents, with regard to an absence of such a rise time in aprotic solvents and strongly hydrogen bond donating solvents, viz., 2,2,2-trifluoroethanol. Rudimentary quantum chemical calculations provide a preliminary idea about the nature of excited state hydrogen bond redistribution involved in the process.

Biomimetic supramolecular polyurethane with sliding polyrotaxane and disulfide bonds for strain sensors with wide sensing range and self-healing capability.

To prolong the service life of flexible electronic materials, polymeric matrixes with excellent self-healing capability and integrated mechanical properties are highly desirable, but the balance between the self-healing capability and mechanical properties is a grand challenge. Here, polyrotaxanes as sliding crosslinkers and dynamic disulfide bonds are incorporated into the main chains of polyurethane (PU) via one-pot synthesis, which endows the PU with polydisperse hard/soft segments, high density of self-healing points and energy dissipation. Based on this judicious molecular design, the PU elastomers exhibit exceptional mechanical properties, such as high stretchability (1167% with a tensile strength of 3.49MPa), high fracture energy (20,775Jm-2) and high puncture energy (200.70mJ). Moreover, due to the presence of dynamic reversible hydrogen and disulfide bonds, the elastomer could achieve stress and strain repair efficiencies of 93.98% and 99.21% at 100 ℃ within 1h, respectively. The above-mentioned superiorities enable the bioinspired strain sensors to possess a large sensing range (∼596%), high sensitivity (∼79.98), short response time (∼128ms), along with excellent reliability and self-healing ability. Besides, the strain sensor exhibits remarkable recyclability and prominent reprocessability, which nicely solves the pollution by discarded electronics.

Self-healing, recyclable, thermally adaptive shape memory functional biopolymers based on multiple dynamic covalent bonds and hydrogen bonds derived from castor oil and vanillin

The development of recyclable biopolymers from renewable resources is of great importance to sustainable development and environmental protection.

Voltage and concentration gradients across membraneless interface generated next to hydrogels: relation to glycocalyx.

Next to many hydrophilic surfaces, including those of biological cells and tissues, a layer of water that effectively excludes solutes and particles can be generated. This interfacial water is the subject of research aiming for practical applications such as removal of salts, pathogens or manipulation of biomolecules. However, the exact mechanism of its creation is still elusive because its persistence and extension contradict hydrogen-bond dynamics and electric double layer predictions. The experimentally recorded negative voltage of this interfacial water remains to be properly explained. Even less is known about the nature of such water layers in biological systems. We present experimental evidence for ion and particle exclusion as a result of separation of ionic charges with distinct diffusion rates across a liquid junction at the gel/water interface and the subsequent repulsion of ions of a given sign by a like-charged gel surface. Gels represent features of biological interfaces (in terms of functional groups and porosity) and are subject to biologically relevant chemical triggers. Our results show that gels with -OSO3- and -COO- groups can effectively generate ion- and particle-depleted regions of water reaching over 100 μm and having negative voltage up to -30 mV. Exclusion distance and electric potential depend on the liquid junction potential at the gel/water interface and on the concentration gradient at the depleted region/bulk interface, respectively. The voltage and extension of these ion- and particle-depleted water layers can be effectively modified by CO2 (respiratory gas) or KH2PO4 (cell metabolite). Possible implications pertain to biologically unstirred water layers and a cell's bioenergetics.

Infrared Analysis and Effect of Nitrogen and Nitrous Oxide on the Glass Transition of Methanol Cryofilms.

Methanol plays an important role in studying the structure and dynamics of hydrogen bonds in alcohols and other physiologically important compounds in the condensed state. The physical vapor deposition method and two-beam interferometry make it possible to study the structure of polyatomic molecules, the nature and character of intermolecular interactions, and the internal structure of various compounds. Thus, it becomes possible to analyze changes in the internal structure of substances near the points of their phase transitions and glass transitions at ultralow temperatures. In this work, we have studied the effect of nitrogen and nitrous oxide on the dependence of refractive indices of methanol on temperature and on structural-phase transformations upon heating from 16 to 160 K.

Preparation of high-strength dynamic polysaccharide nanocomposite hydrogels and their application towards dye adsorption

The preparation and application of natural dynamic polysaccharide hydrogels have been attractive in recent years. Herein, carboxymethyl chitosan (CMCht) and oxidized acetoacetate cellulose (OCAA) were used to prepare polysaccharide nanocomposite hydrogel for dye adsorbent by one pot method mixing glutaraldehyde (GA) and cellulose nanofibers (CNFs), and mechanical, rheological, self-healing and dye adsorption properties were investigated. Consequently, compared with CMCht/OCAA hydrogel, the addition of GA crosslinker together with 1 % CNF increased strengths by ∼520 %, tensile strengths from 259 KPa to 1.35 MPa and compressive strength from 450 KPa to 2.35 MPa, respectively. The nanocomposite hydrogels demonstrated excellent anti-fatigue performance, and its experimental modulus result was fit Halpin-Kardos and Ouali model. Moreover, the freeze-dried gels showed a good removal effect for methylene blue dye from water, and its adsorption capacity and removal efficiency could reach up to 564.64 mg/g and 94 % due to the presence of dynamic covalent and hydrogen bonds in the composite hydrogel. This work developed a high-strength dynamic polysaccharide hydrogels incorporation of CNFs, which shows promising applications in environmental fields especially water pollution adsorption treatment.

Hydrogen-Bonding Bottlebrush Networks: Self-Healing Materials from Super-Soft to Stiff

The impact of polymer architecture on network dynamics and self-healing is presented using bottlebrushes containing side chains that are end-functionalized with 2-ureido-4[1H]-pyrimidinone (UPy). The synthesis of these materials is straightforward through a three-step process: (1) synthesizing rubbery poly(4-methylcaprolactone) macromonomers (p4MCL–OH) with a norbornene-based initiator, (2) functionalizing the terminal hydroxyl group with UPy–isocyanate (p4MCL–UPy), and (3) statistically copolymerizing p4MCL–OH and p4MCL–UPy via ring-opening metathesis polymerization (ROMP) to form hydrogen-bonding bottlebrushes having a fraction (p) of side chains functionalized with UPy. Attaching UPy to the free end of bottlebrush side chains dilutes the impact of friction from complementary UPy interactions on segmental dynamics, leading to a much weaker dependence of the glass-transition temperature (Tg) on p than observed in linear analogues, while the activation energy to dissociate UPy–UPy bonds (41–47 kJ/mol) remains mostly unchanged. Longer side chains result in a competition between reducing Tg and inducing entanglements that influence hydrogen-bonded network dynamics. Increasing the backbone length extends the sticky Rouse region without affecting the network modulus (Gx) or UPy–UPy dissociation time (τs). Gx scales linearly with p and ranges from 27 kPa to 1.6 MPa, while τs remains nearly constant in contrast to linear telechelic ionomers, implying a similar self-healability across bottlebrush networks containing different amounts of UPy. These stretchable networks with p ≤ 0.25 undergo self-healing upon repeated rupture and melt pressing at ≤100 °C while retaining similar tensile properties. In summary, decorating bottlebrush polymers with hydrogen bonds creates opportunities to independently manipulate associative network dynamics and mechanical moduli.

Solvent-free synthesis of high-performance polyurethane elastomer based on low-molecular-weight alkali lignin

Using cheap and green lignin as a partial substitute for petroleum-based polyols is highly attractive for sustainable development of polyurethane elastomers (LPUes). However, the traditional synthesis process of LPUes inevitably uses toxic solvents that are difficult to remove or carcinogenic. Here, we reported a solvent-free synthesis method to prepare lignin-containing polyurethane elastomers (SF-LPUes) with high strength, high toughness and high elasticity. Most of the hydroxyl groups of lignin reacted with isocyanates to form a strong chemical cross-linking network, while the unreacted ones formed a dynamic hydrogen bond network with polyurethane matrix, contributing to the in-situ formation of lignin nanoparticles to build a nano-micro phase separation structure. Consequently, a dual-crosslinking network structure was formed and endowed SF-LPUes with excellent mechanical properties. Especially, the SF-LPUes prepared from low molecular alkali lignin possessed a tensile strength as high as 38.2 MPa, a maximum elongation at break of 1108 %, and an elastic recovery ratio of up to 98.7 %. Moreover, SF-LPUes showed impressing reprocessing performance and aging resistance. This work provides an industrial application prospect for the synthesis of lignin-containing polyurethane elastomers via a solvent-free synthesis process.

A tough, healable, and recyclable conductive polyurethane/carbon nanotube composite

Recently, conductive composites have been used in flexible electronic devices and have attracted attention. The integration of self-healing, high sensitivity, large tensile strength, environmental stability, and easy recyclability into conductive composites is very desirable yet challenging. Hence, a conductive composite as a flexible strain sensor with a self-healing and recyclability is facilely developed, with a polyurethane (PU) elastomer bearing dynamic boronic ester as the polymer matrix and carbon nanotubes (CNTs) as a conductive filler. Due to the dynamic boronic ester bond and hydrogen bond, the prepared polyurethane conductive composite has good self-healing and mechanical properties. It not only has a high healing efficiency of 78 % but also has a tensile strength of 15.4 MPa and an elongation at break of 420 %. In addition, the prepared conductive composite has high conductivity (0.57 mS/cm) and sensitivity. As a wearable sensor, it can identify human activities in all directions, such as elbow and finger bending, speaking, and facial changes. Consequently, the polyurethane conductive composite prepared in this study exhibited wonderful application potential in wearable electronic devices such as self-healing strain sensors.

The Interplay between ESIPT and TADF for the 2,2'-Bipyridine-3,3'-diol: A Theoretical Reconsideration.

Organic molecules with excited-state intramolecular proton transfer (ESIPT) and thermally activated delayed fluorescence (TADF) properties have great potential for realizing efficient organic light-emitting diodes (OLEDs). Furthermore, 2,2'-bipyridine-3,3'-diol (BP(OH)2) is a typical molecule with ESIPT and TADF properties. Previously, the double ESIPT state was proved to be a luminescent state, and the T2 state plays a dominant role in TADF for the molecule. Nevertheless, whether BP(OH)2 undergoes a double or single ESIPT process is controversial. Since different ESIPT channels will bring different TADF mechanisms, the previously proposed TADF mechanism based on the double ESIPT structure for BP(OH)2 needs to be reconsidered. Herein, reduced density gradient, potential energy surface, IR spectra and exited-state hydrogen-bond dynamics computations confirm that BP(OH)2 undergoes the barrierless single ESIPT process rather than the double ESIPT process with a barrier. Moreover, based on the single ESIPT structure, we calculated spin-orbit coupling matrix elements, nonradiative rates and electron-hole distributions. These results disclose that the T3 state plays a predominant role in TADF. Our investigation provides a better understanding on the TADF mechanism in hydrogen-bonded molecular systems and the interaction between ESIPT and TADF, which further provides a reference for developing efficient OLEDs.

Janus regulation of ice growth by hyperbranched polyglycerols generating dynamic hydrogen bonding

In this study, a new phenomenon describing the Janus effect on ice growth by hyperbranched polyglycerols, which can align the surrounding water molecules, has been identified. Even with an identical polyglycerol, we not only induced to inhibit ice growth and recrystallization, but also to promote the growth rate of ice that is more than twice that of pure water. By investigating the polymer architecture and population, we found that the stark difference in the generation of quasi-structured H2O molecules at the ice/water interface played a crucial role in the outcome of these opposite effects. Inhibition activity was induced when polymers at nearly fixed loci formed steady hydrogen bonding with the ice surface. However, the formation-and-dissociation dynamics of the interfacial hydrogen bonds, originating from and maintained by migrating polymers, resulted in an enhanced quasi-liquid layer that facilitated ice growth. Such ice growth activity is a unique property unseen in natural antifreeze proteins or their mimetic materials.

A sustainable reinforced-concrete-structured sponge for highly-recyclable oil adsorption

A reinforced-concrete-structured sponge based on amino-terminated polydimethylsiloxane (PDMS) and carboxyl carbon nanotubes (CCNTs) is synthesized, without any templates or coatings. The covalent bonding of PDMS and CCNTs generate amide groups which provide considerable hydrogen bonds. The synergistic effect of dynamic hydrogen bonds and flexible PDMS chains contribute to the high elasticity, while CCNTs affect the stress. The compressive and tensile stress-train curves both overlap with the first curves during multiple load-release cycles, at the compressive strain of 80% and the tensile strain of 100%, respectively. The amount of CCNTs determines the porosity, and significantly affects the hydrophobicity. The sponge is applied to static oil adsorption, oil/water emulsion separation and oil-spill treatment. Due to the high elasticity and anti-fatigue performance, the sponge can be repeatedly regenerated using a simple squeezing method. The adsorption capacity still reaches 99.45% after 30 adsorption–desorption cycles. The weight, morphology and hydrophobicity of the sponge maintain unchanged, either. The simulation of oil-spill treatment demonstrates that the sponge can also work efficiently under dynamic conditions. The high elasticity, recyclability and stability propose the sponge to be a promising material for oily-water treatment in complex circumstances.

Room-temperature self-healing graphene/rubber-based supramolecular elastomers utilized by dynamic boroxines and hydrogen bonds for human motion detection

Flexible electronic sensors with self-healing capabilities exhibit distinctive fascination in human motion detection. However, it remains challenging in the mechanically robustness, highly healing efficiency, mildly healing condition, and steady electrical performance. Here, a self-healing nanostructured graphene/rubber-based supramolecular elastomer (GRSE) with a covalent/non-covalent system is rationally designed. The 1-pyrenamine-modified graphene nanosheets (GPA) disperse uniformly on the modified epoxy natural rubber (S-ENR), leading to good electrical conductivity (0.0029 S−1 m), low percolation threshold (2.73 wt%), a fast-response time (250 ms), and a low stress-strain detection range (1 %). Based on the synergistic effect of dynamic boroxines and interfacial hydrogen binding, GRSE-based sensor exhibits excellent mechanical strength (3.46 MPa) and high-performance healing efficiency (η = 91.1 %) at room temperature. The GRSE-based sensor can still detect precise and stable sensing signals accurately in human movements (including breath, speech, facial expression, and joint motion) after healing, implying a promising route to develop an efficient and robust self-healing flexible sensor for the more durable human motion detection in practice.