An interfacial robust and entire self-healing ionogel-elastomer hybrid for elastic electronics enables discretionary assembly and reconfiguration

Inspired by the multi-layer architecture of mammal skins,interfacial robust,stretchable,and entirely healable gel-elastomer hybrids hold great potential in diverse fields including biomedical devices,wearable electrical devices,and soft robotics.However,existing gel-elastomer hybrids have numerous limitations including low interfacial bonding toughness,complex and time-consuming preparation process,unhealable,and non-reconfiguration.Herein,we propose a simple and general chemical strategy through the interfacial dynamic bonding between gel and elastomer to simultaneously address the abovementioned obstacles.Dynamic covalent bonds readily and repeatably covalent bonding ionogel and elastomer(interfacial toughness:390 J m^(-2)),endowed the hybrids with entire self-healing features like skin and enabled discretionary assembly and reconfiguration.Moreover,this strategy resolved the troublesome contradiction between interfacial stability and reconfiguration.Taking advantage of the aforementioned features,we readily constructed a multi-module,self-healing,self-powered,and realtime monitoring of personal status integrated elastic electronics,which could simply reconfigure the output signal of elastic electronics into an input signal of the devices-braille keyboard.

Breathable,antifreezing,mechanically skin-like hydrogel textile wound dressings with dual antibacterial mechanisms

Hydrogels are emerging as the most promising dressings due to their excellent biocompatibility,extracellular matrix mimicking structure,and drug loading ability.However,existing hydrogel dressings exhibit limited breathability,poor environmental adaptability,potential drug resistance,and limited drug options,which extremely restrict their therapeutic effect and working scenarios.Here,the current research introduces the first paradigm of hydrogel textile dressings based on novel gelatin glycerin hydrogel(glyhydrogel)fibers fabricated by the Hofmeister effect based wet spinning.Benefiting from the unique knitted structure,the textile dressing features excellent breathability(1800 times that of the commercially available 3 M dressing)and stretchability(535.51±38.66%).Furthermore,the glyhydrogel textile dressing can also withstand the extreme temperature of-80℃,showing the potential for application in subzero environments.Moreover,the introduction of glycerin endows the textile dressing with remarkable antibacterial property and expands the selection of loaded drugs(e.g.,clindamycin).The prepared glyhydrogel textile dressing shows an excellent infected wound healing effect with a complete rat skin closure within 14 days.All these functions have not been achievable by traditional hydrogel dressings and provide a new approach for the development of hydrogel dressings.

Solution-processed wafer-scale nanoassembly of conducting polymers enables selective ultratrace nerve agent detection at low power

There is a great interest in developing microelectronic devices based on nanostructured conducting polymers that can selectively electro-couple analytes at high sensitivity and low power.Nanostructured conducting polymers have emerged as promising candidates for this technology due to their excellent stability with low redox potential,high conductivity,and selectivity endowed by chemical functionalization.However,it remains challenging to develop cost-effective and large-scale assembly approaches for functionalized conducting polymers in the practical fabrication of electronic devices.Here,we reported a straightforward waferscale assembly of nanostructured hexafluoroisopropanol functionalized poly(3,4-ethylenedioxythiophene)(PEDOT-HFIP)on smooth substrates.This approach is template-free,solution-processed,and adaptable to conductive and nonconductive substrates.By this approach,the nanostructured PEDOT-HFIPs could be easily integrated onto interdigitated electrodes with intimate ohmic contact.At the optimized space-to-volume ratio,we demonstrated a low-power,sensitive,and selective nerve agent sensing technology using this platform by detecting sarin vapor with a limit of detection(LOD)of 10 ppb and signal strength of 400 times the water interference at the same concentration,offering significant advantages over existing similar technologies.We envision that its easy scale-up,micro size,small power consumption,and combination of high sensitivity and selectivity make it attractive for various wearable platforms.

Solvent-Free Synthesis of Self-Healable and Recyclable Crosslinked Polyurethane Based on Dynamic Oxime-Urethane Bonds

Polyurethane is widely used for its versatility in design and range of performance.Self-healing and recyclable dynamic polyurethane networks have attracted extensive attention due to their potential to extend service life and ensure safety in use,as well as to promote sustainable use of resources.Developing green and environment-friendly methods to obtain this material is an interesting and challenging task,as the majority of current dynamic polyurethane networks utilize the solution polymerization method.The use of solvents makes the processes complicated,harmful to environment,and increase the cost.Poly(oxime-urethanes)(POUs)are emerging dynamic polyurethanes and show great potential in diverse fields,such as biomaterials,hot melt adhesives,and flexible electronics.In this study,we utilized the solubility properties of dimethylglyoxime in raw material poly(ethylene glycol)to prepare POUs through bulk polymerization for the first time.This method is simple,convenient and cost-efficient.Simultaneously,copper ion coordination improves POUs strength and dynamic properties,with mechanical strength up from 0.54 MPa to 1.03 MPa and self-healing recovery rate up from 85.5%to 91.8%,and activation energy down from 119.6 k J/mol to 95.4 k J/mol.To demonstrate the application of this technology,self-healing and stretchable circuits are constructed from this dynamic polyurethane network.

A topological polymer network with Cu(Ⅱ)-coordinated reversible imidazole-urea locked unit constructs an ultra-strong self-healing elastomer

It is exceedingly desired, but difficult to construct self-healing materials with both excellent mechanical properties and healing efficiency, which are usually realized by using mutually exclusive methods. Here, we reconcile this contradiction by utilizing copper-bis-(imidazole-2-yl)-methane-urea(Cu-BIMU) locked units based on novel designed dynamic imidazole-urea bonds with coupled multiple noncovalent bonds(coordination bonds, π-π stacking bonds, and hydrogen bonds). The coordination of Cu(II) greatly reduces the electron-cloud density of imidazole, which lowers the free energy barrier of imidazole-urea bonds and promotes their reversible dissociation, as demonstrated by the density functional theory and small-molecule model reaction. The topological design of Cu-BIMU polyurethane(Cu-BIMU-PU), which concentrates multiple crosslinking-in-one locked unit to avoid the formation of excessive crosslinking sites to ensure high chain mobility, facilitates self-healing. Accumulative extensive intermolecular interactions endowed excellent mechanical properties to the resulting Cu-BIMU-PU elastomer with a tensile strength of 65.3 MPa, among the highest ever-reported value. This work provides a novel molecular design principle for fabricating high-performance dynamic polymers.

Cooperative Chemical Coupling and Physical Lubrication Effects Construct Highly Dynamic Ionic Covalent Adaptable Network for High-Performance Wearable Electronics

Covalent adaptable networks(CANs),which combine the benefits of traditional thermosets and thermoplastics,have attracted considerable attention.The dynamics of reversible covalent bonds and mobility of polymer chains in CANs determine the topological rearrangement of the polymeric network,which is critical to their superior features,such as self-healing and reprocessing.Herein,we introduce an ionic liquid to dimethylglyoximeurethane(DOU)-based CANs to regulate both reversible bond dynamics and polymer chain mobility by cooperative chemical coupling and physical lubrication.Small-molecule model experiments demonstrated that ionic liquids can catalyze dynamic DOU bond exchange.Ionic liquid also breaks the hydrogen bonds between polymeric chains,thereby increasing their mobility.As a combined result,the activation energy of the dissociation of the dynamic network decreased from 110 to 85 kJ mol^(−1).Furthermore,as a functional moiety,the ionic liquid imparts new properties to CANs and will greatly expand their applications.For example,the consequent conductivity of resultant ionic CAN(iCAN)has demonstrated a great power to build high-performance multifunctional wearable electronics responsive to multiple stimulations including temperature,strain,and humidity.This study provides a new design principle that simultaneously uses the chemical and physical effects of two structural components to regulate material properties enabling novel applications.

Dynamic Oxime-Urethane Bonds, a Versatile Unit of High Performance Self-healing Polymers for Diverse Applications

Oxime-urethane bond featuring with high reversibility even at room temperature and multiple reactivity is an emerging dynamic covalent bond,and has shown great potential for self-healing polymers,which are one of the most attractive development directions for next generation of polymeric materials.In this review,recent progresses on the oxime-urethane-based self-healing polymers,including their designs and applications in diverse fields such as biomedicine,flexible electronics,soft robots,3D printing,protective materials,and adhesives,are summarized,and outlooks on the future development of this field are discussed.

Highly Transparent,Stretchable,and Self‑Healable Ionogel for Multifunctional Sensors,Triboelectric Nanogenerator,and Wearable Fibrous Electronics

Ionogels with high transparency,stretchability and self-healing capability show great potential for wearable electronics.Here,a kind of highly transparent,stretchable and self-healable ionogels are designed using double physical cross-linking including hydrogen bonding and dipole–dipole interaction.Owing to the dynamic and reversible nature of the ion–dipole interaction and hydrogen bonds of polymeric chains,the ionogel possesses good self-healing capability.The multifunctional sensors for strain and temperature are fabricated based on ionogel.The ionogel can serve as strain sensor that exhibited high sensitivity[gauge factor(GF)=3.06]and durability(1000 cycles)to a wide range of strains(0–300%).Meanwhile,the ionogel shows rapid response to temperature,due to the temperature dependence of its ionic conductivity.Furthermore,the ionogel fbers with excellent antifreezing(−20°C)capability are fabricated,and the fbers show the good sensing performance to human motions and temperature.Importantly,the antifreezing ionogel-based triboelectric nanogenerator(ITENG)is assembled for efcient energy harvesting.The ITENG shows a short circuit current(ISC)of 6.1μA,open circuit voltage(VOC)of 115 V,and instantaneous peak power density of 334 mW m−2.This work provides a new strategy to design ionogels for the advancement of wearable electronics.

3D printing preview for stereo-lithography based on photopolymerization kinetic models

The diversity of biomedical applications makes stereolithographic(SL)three-dimensional(3D)printing process complex.A strategy was developed to simulate the layer-by-layer fabrication of 3D printed products combining polymerization kinetic with reaction conditions to realize print preview.As a representative example,the typical UV-curable dental materials based on epoxy acrylate and photoinitiator with different molar ratios was exposed under varying intensity of UV light to verify the simulation results.A theoretical kinetics model containing oxygen inhibition was established.In-situ FTIR was employed to measure propagation and termination constants while coupled UV/vis was performed to examine the law of light attenuation during cure reaction,even with various colours and additives.Simulation results showed that the correlation coefficient square between the experiments and simulations of epoxy acrylate with 1%,2%and 3%initiator upon 20 mW/cm2 UV light are 0.8959,0.9324 and 0.9337,respectively.Consequently,our simulation of photopolymerization for SL 3D printing successfully realized visualization of printing quality before practically printing the targeted biomedical objects with complex topology structures.

Supertough spontaneously self-healing polymer based on septuple dynamic bonds integrated in one chemical group

The development of spontaneously self-healing materials with excellent mechanical properties remains a formidable challenge despite the extensive interest in such materials. This is because the self-healing and mechanical properties of a material are usually optimized via contradictory routes. The present study demonstrated a supertough spontaneously self-healing polymer,Fe-(2,6-diacetylpyridine dioxime)-urethane-based polyurethane(Fe-PPOU) based on septuple dynamic bonds integrated in one chemical group. A synergistic effect was induced by the presence of multiple dynamic crosslinking points, which comprised the integrated dynamic interactions, and the hidden lengths of the folded polymeric chains in Fe-PPOU. Thus, the mechanical and self-healing properties of the polymer were simultaneously optimized. Fe-PPOU demonstrated the highest reported toughness(139.8 MJ m^(-3)) among all the room-temperature spontaneously self-healing polymers with a nearly 100% healing rate. Fe-PPOU exhibited instant(30 s) self-healing to reach a strength of 1.6 MPa that was higher than the original strength of numerous recently reported self-healing polymers.

Three-dimensional-printed polycaprolactone scaffolds with interconnected hollow-pipe structures for enhanced bone regeneration

Three-dimensional(3D)-printed scaffolds are widely used in tissue engineering to help regenerate critical-sized bone defects.However,conventional scaffolds possess relatively simple porous structures that limit the delivery of oxygen and nutrients to cells,leading to insufficient bone regeneration.Accordingly,in the present study,perfusable and permeable polycaprolactone scaffolds with highly interconnected hollow-pipe structures that mimic natural micro-vascular networks are prepared by an indirect onepot 3D-printing method.In vitro experiments demonstrate that hollow-pipe-structured(HPS)scaffolds promote cell attachment,proliferation,osteogenesis and angiogenesis compared to the normal non-hollow-pipe-structured scaffolds.Furthermore,in vivo studies reveal that HPS scaffolds enhance bone regeneration and vascularization in rabbit bone defects,as observed at 8 and 12weeks,respectively.Thus,the fabricated HPS scaffolds are promising candidates for the repair of critical-sized bone defects.

Long-Range Electronic Effect-Promoted Ring-Opening Polymerization of Thioctic Acid to Produce Biomimetic Ionic Elastomers for Bioelectronics

Poly(disulfide)s have been widely used in flexible wearable electronics,smart materials,and drug delivery.The synthesis of poly(disulfide)s usually utilizes external stimuli or toxic initiators to promote the polymerization.Here,we indicated that the long-range electronic effect can significantly alter the reactivity of the disulfide group.Accordingly,we established deprotonation-promoted ring-opening polymerization of thioctic acid(TA)as a highly effective and simple method to synthesize poly(disulfide)s due to the long-range electronic effect and nucleophilic carboxylate.Without external stimuli and initiators,simple mixing of TA and deprotonation reagent,choline bicarbonate,in different ratios at room temperature rapidly produced a series of high molecular weight(up to 772 kDa)ionic liquid crystal poly(disulfide)s elastomers with room temperature self-healing ability,adjustable conductivity(2.39×10^(−2)∼0.28×10^(−2)S m^(−1)),degradability,biocompatibility,antibacterial property,and tissue-like softness(Young’s moduli ranging from 18.2±6.0 to 111.1±36.7 kPa).The experiments and density functional theory calculations also revealed the principle of long-range electronic effect to establish a new synthetic strategy of poly(disulfide)s with superior properties favorable for bioelectronics.