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Smart tactile sensing materials have excellent development prospects, including wearable health-monitoring equipment and energy collection. Hydrogels have received extensive attention in tactile sensing owing to their transparency and high elasticity. In this study, highly crosslinked hydrogels are fabricated by chemically crosslinking polyacrylamide with lithium magnesium silicate and decorated with carbon quantum dots. Magnesium lithium silicate provides abundant covalent bonds and improves the mechanical properties of the hydrogels. The luminescent properties endowed by the carbon dots further broaden the application of hydrogels for realizing flexible electronics. The hydrogel-based strain sensor exhibits excellent sensitivity (gauge factor 2.6), a broad strain response range (0-2000%), good cyclicity, and durability (1250). Strain sensors can be used to detect human motions. More importantly, the hydrogel can also be used as a flexible self-supporting triboelectric electrode for effectively detecting pressure in the range of 1-25 N and delivering a short-circuit current (ISC ) of 2.6 µA, open-circuit voltage (VOC ) of 115 V, and short-circuit transfer charge (QSC ) of 29 nC. The results reveal new possibilities for human-computer interactions and electronic robot skins.
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Carbono , Dispositivos Eletrônicos Vestíveis , Humanos , Hidrogéis/química , Lítio , Tato , Condutividade ElétricaRESUMO
Molecular photoswitches are considered to be important candidates in the field of solar energy storage due to their sensitive and reversible bidirectional optical response. Nevertheless, it is still a daunting challenge to design a molecular photoswitch to improve the low solar spectrum utilization and quantum yields while achieving charging and discharging of heat without solvent assistance. Herein, a series of visible-light-driven ethylene-bridged azobenzene (b-Azo) chromophores with different alkyne substituents which can undergo isomerization reactions promoted in both directions by visible light are reported. Their visible light responsiveness improves their solar spectrum utilization while also having high quantum yields. In addition, as the compounds are liquids, there is no need to dissolve the compounds in order to exploit this switching. The photoisomerization of b-Azo can be adjusted by alkyne-related substituents, and hexyne-substituted b-Azo is able to store and release photothermal energy with a high density of 106.1 J·g-1, and can achieve a temperature increase of 1.8 °C at a low temperature of -1 °C.
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Development of renewable energy technologies has been a significant area of research amongst scientists with the aim of attaining a sustainable world society. Solar thermal fuels that can capture, convert, store, and release solar energy in the form of heat through reversible photoisomerization of molecular photoswitches such as azobenzene derivatives are currently in the limelight of research. Herein, we provide a state-of-the-art account on the recent advancements in solar thermal fuels based on azobenzene photoswitches. We begin with an overview on the importance of azobenzene-based solar thermal fuels and their fundamentals. Then, we highlight the recent advances in diverse azobenzene materials for solar thermal fuels such as pure azobenzene derivatives, nanocarbon-templated azobenzene, and polymer-templated azobenzene. The basic design concepts of these advanced solar energy storage materials are discussed, and their promising applications are highlighted. We then introduce the recent endeavors in the molecular design of azobenzene derivatives toward efficient solar thermal fuels, and conclude with new perspectives on the future scope, opportunities and challenges. It is expected that continuous pioneering research involving scientists and engineers from diverse technological backgrounds could trigger the rapid advancement of this important interdisciplinary field, which embraces chemistry, physics, engineering, nanoscience, nanotechnology, materials science, polymer science, etc.
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In recent years, with the rapid advancement in various high-tech technologies, efficient heat dissipation has become a key issue restricting the further development of high-power-density electronic devices and components. Concurrently, the demand for thermal comfort has increased; making effective personal thermal management a current research hotspot. There is a growing demand for thermally conductive materials that are diversified and specific. Therefore, smart thermally conductive fiber materials characterized by their high thermal conductivity and smart response properties have gained increasing attention. This review provides a comprehensive overview of emerging materials and approaches in the development of smart thermally conductive fiber materials. It categorizes them into composite thermally conductive fibers filled with high thermal conductivity fillers, electrically heated thermally conductive fiber materials, thermally radiative thermally conductive fiber materials, and phase change thermally conductive fiber materials. Finally, the challenges and opportunities faced by smart thermally conductive fiber materials are discussed and prospects for their future development are presented.
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To address the escalating power consumption of processors in data centers and the growing emphasis on environmental sustainability, the prospective shift from traditional air-cooling to immersion liquid cooling necessitates multiple functional integrations in polymer-based thermal conductive materials. Here, drawing inspiration from mussels, we showed a copolymer, poly(dimethylsiloxane-co-dopamine methacrylate) (PDMS-DMA), with a variety of reversible molecular interactions and simply combined with liquid metal (EGaIn) can yield a flexible, waterproof, and electrically insulating thermal conductive composite. The obtained PDMS-DMA/EGaIn composites demonstrate a harmonious blend of attributes, including a low modulus (75.8 kPa), high thermal conductivity of 6.9 W m-1 K-1, and rapid room-temperature self-healing capabilities, capable of complete repair within 20 min, even under water. Based on its electrically insulating and water resistance properties, PDMS-DMA/EGaIn emerges as a promising candidate for efficient and stable heat transfer in both air and underwater thermal management. Consequently, this water-resistant polymer-based composite holds significance for application in thermal protective layers for future immersion liquid cooling systems.
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Interface thermal resistance has become a crucial barrier to effective thermal management in high-performance electronics and sensors. The growing complexity of operational conditions, such as irregular and dynamic surfaces, demands thermal interface materials (TIMs) to possess high thermal conductivity and soft elasticity. However, developing materials that simultaneously combine soft elasticity and high thermal conductivity remains a challenging task. Herein, we utilize a vertically oriented graphene aerogel (VGA) and rationally design liquid metal (LM) networks to achieve directional and adjustable pathways within the composite. Subsequently, we leverage the advantages of the low elastic modulus and high deformation capabilities of brush-shaped polydimethylsiloxane (BPDMS), together with the bicontinuous thermal conduction path constructed by VGA and LM networks. Ultimately, the designed composite of patterned liquid metal/vertically oriented graphene aerogel/brush-shaped PDMS (LM-VGA/BPDMS) shows a high thermal conductivity (7.11 W m-1 K-1), an ultra-low elastic modulus (10.13 kPa), excellent resilience, and a low interface thermal resistance (14.1 K mm2 W-1). This LM-VGA/BPDMS soft composite showcases a stable heat dissipation capability at dynamically changing interfaces, as well as excellent adaptability to different irregular surfaces. This strategy holds important application prospects in the fields of interface thermal management and thermal sensing in extremely complex environments.
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The controllability of the microstructure of a compressed hierarchical building block is essential for optimizing a variety of performance parameters, such as thermal management. However, owing to the strong orientation effect during compression molding, optimizing the alignment of materials perpendicular to the direction of pressure is challenging. Herein, to illustrate the effect of the ordered microstructure on heat dissipation, thermally conductive carbon-based materials are fabricated by tailoring dense, orientation-tunable, and interleaved structures. Vertically aligned carbon nanotube arrays (VACNTs) interconnected with graphene films (GF) are prepared as a 3D core-ordered material to fabricate compressed building blocks of O-VA-GF and S-VA-GF. Leveraging the densified interleaved structure offered by VACNTs, the hierarchical O-VA-GF achieves excellent through-plane (41.7 W m-1 K-1 ) and in-plane (397.9 W m-1 K-1 ) thermal conductivities, outperforming similar composites of S-VA-GF (through-plane: 10.3 W m-1 K-1 and in-plane: 240.9 W m-1 K-1 ) with horizontally collapsed carbon nanotubes. As heat dissipation plates, these orderly assembled composites yield a 144% and 44% enhancement in the cooling coefficient compared with conventional Si3 N4 for cooling high-power light-emitting diode chips.
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The energy storage mechanism of azobenzene is based on the transformation of molecular cis and trans isomerization, while NBD/QC, DHA/VHF, and fulvalene dimetal complexes realize the energy storage function by changing the molecular structure. Acting as "molecular batteries," they can exhibit excellent charging and discharging behavior by converting between trans and cis isomers or changing molecular structure upon absorption of ultraviolet light. Key properties determining the performance of STFs are stored energy, energy density, half-life, and solar energy conversion efficiency. This review is aiming to provide a comprehensive and authoritative overview on the recent advancements of azobenzene molecular photoswitch system in STFs fields, including derivatives and carbon nano-templates, which is emphasized for its attractive performance. Although the energy storage performance of Azo-STFs has already reached the level of commercial lithium batteries, the cycling capability and controllable release of energy still need to be further explored. For this, some potential solutions to the cycle performance are proposed, and the methods of azobenzene controllable energy release are summarized. Moreover, energy stored by STFs can be released in the form of mechanical energy, which in turn can also promote the release of thermal energy from STFs, implying that there could be a relationship between mechanical and thermal energy in Azo-STFs, providing a potential direction for further research on Azo-STFs.
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Heat and stress transfer at an interface are crucial for the contact-based tactile sensing to measure the temperature, morphology, and modulus. However, fabricating a smart sensing material that combines high thermal conductivity, elasticity, and good adhesion is challenging. In this study, a composite is fabricated using a directional template of vertically aligned folded graphene (VAFG) and a copolymer matrix of poly-2-[[(butylamino)carbonyl]oxy]ethyl ester and polydimethylsiloxane, vinyl-end-terminated polydimethylsiloxane (poly(PBAx-ran-PDMS)). With optimized chemical cross-linking and supermolecular interactions, the poly(PBA-ran-PDMS)/VAFG exhibits high thermal conductivity (15.49 W m-1 K-1 ), an high elastic deformation, and an interfacial adhesion of up to 6500 N m-1 . Poly(PBA-ran-PDMS)/VAFG is highly sensitive to temperature and pressure and demonstrates a self-learning capacity for manipulator applications. The smart manipulator can distinguish and selectively capture unknown materials in the dark. Thermally conductive, elastic, and adhesive poly(PBA-ran-PDMS)/VAFG can be developed into core materials in intelligent soft robots.
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Composites that can rapidly self-healing their structure and function at room temperature have broad application prospects. However, in view of the complexity of composite structure and composition, its self-heal is facing challenges. In this article, supramolecular effect is proposed to repair the multistage structure, mechanical and thermal properties of composite materials. A stiff and tough supramolecular frameworks of 2-[[(butylamino)carbonyl]oxy]ethyl ester (PBA)-polydimethylsiloxane (PDMS) were established using a chain extender with double amide bonds in a side chain to extend prepolymers through copolymerization. Then, by introducing the copolymer into a folded graphene film (FGf), a highly thermally conductive composite of PBA-PDMS/FGf with self-healing capacity was fabricated. The ratio of crosslinking and hydrogen bonding was optimized to ensure that PBA-PDMS could completely self-heal at room temperature in 10 min. Additionally, PBA-PDMS/FGf exhibits a high tensile strength of 2.23 ± 0.15 MPa at break and high thermal conductivity of 13 ± 0.2 W m-1 K-1; of which the self-healing efficiencies were 100% and 98.65% at room temperature for tensile strength and thermal conductivity, respectively. The excellent self-healing performance comes from the efficient supramolecular interaction between polymer molecules, as well as polymer molecule and graphene. This kind of thermal conductive self-healing composite has important application prospects in the heat dissipation field of next generation electronic devices in the future.
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Molecular light-harvesting capabilities and the production of low-temperature heat output are essential for flexible self-heated textiles. An effective strategy to achieve these characteristics is to introduce photoresponsive molecular interactions (photodynamic bonds) to increase the energy storage capacity and optimize the low-temperature photochromic kinetics. In this study, a series of sulfonic-grafted azobenzene-based polymers interacted with different metal ions (PAzo-M, M = Mg, Ca, Ni, Zn, Cu, and Fe) to optimize the energy level and isomerization kinetics of these polymers is designed and prepared. Photoinduced formation and dissociation of MO dynamic bonds enlarge the energy gap (∆E) between trans and cis isomers for high-energy storage and favor a high rate of isomerization for low-temperature heat release. The suitable binding energy and high ∆E enable PAzo-M to store and release isomerization energy and bond enthalpy even in a low-temperature (-5 °C) environment. PAzo-Mg possesses the highest energy storage density of 408.6 J g-1 (113.5 Wh kg-1 ). A flexible textile coated with PAzo-Mg can provide a high rise in temperature of 7.7-12.5 °C in a low-temperature (-5.0 to 5.0 °C) environment by selectively self-releasing heat indoors and outdoors. The flexible textile provides a new pathway for wearable thermal management devices.
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Temperatura Alta , Têxteis , Íons , Isomerismo , PolímerosRESUMO
In order to compare the effects of iopromide and isoxazole on postoperative contrast-induced nephropathy in patients with renal insufficiency, the paper searches for randomized controlled trials and retrospective cohort studies comparing the effects of iopromide and iodixanol on renal function in patients with renal insufficiency after surgery. The data are extracted from eligible studies. We tried to assess the incidence of contrast-agent nephropathy, preoperative and postoperative serum creatinine indicators, and mortality. This paper includes 8 studies with a total of 1243 patients. The incidence of contrast-induced nephropathy in the iopromide group is higher than that in the iodixanol group, and there is no significant difference between the two groups in postoperative mortality and preoperative serum creatinine expression. Sensitivity analysis and funnel chart show that our research is robust and has low publication bias. Our research shows that in patients with renal insufficiency, the incidence of contrast-medium nephropathy in the iopromide group is higher than that in the iodixanol group. Iodixanol is safer and has less effect on patients' serum creatinine levels.
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Nefropatias , Insuficiência Renal , Meios de Contraste/efeitos adversos , Creatinina/efeitos adversos , Feminino , Humanos , Iohexol/análogos & derivados , Nefropatias/induzido quimicamente , Masculino , Insuficiência Renal/induzido quimicamente , Insuficiência Renal/complicações , Insuficiência Renal/epidemiologia , Estudos Retrospectivos , Ácidos Tri-IodobenzoicosRESUMO
Soft robots that can move like living organisms and adapt to their surroundings are currently in the limelight from fundamental studies to technological applications, due to their advances in material flexibility, human-friendly interaction, and biological adaptation that surpass conventional rigid machines. Light-fueled smart actuators based on responsive soft materials are considered to be one of the most promising candidates to promote the field of untethered soft robotics, thereby attracting considerable attention amongst materials scientists and microroboticists to investigate photomechanics, photoswitch, bioinspired design, and actuation realization. In this review, we discuss the recent state-of-the-art advances in light-driven bimorph soft actuators, with the focus on bilayer strategy, i.e., integration between photoactive and passive layers within a single material system. Bilayer structures can endow soft actuators with unprecedented features such as ultrasensitivity, programmability, superior compatibility, robustness, and sophistication in controllability. We begin with an explanation about the working principle of bimorph soft actuators and introduction of a synthesis pathway toward light-responsive materials for soft robotics. Then, photothermal and photochemical bimorph soft actuators are sequentially introduced, with an emphasis on the design strategy, actuation performance, underlying mechanism, and emerging applications. Finally, this review is concluded with a perspective on the existing challenges and future opportunities in this nascent research Frontier.
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Robótica , HumanosRESUMO
An enhanced photoinduced reversible switching of graphene oxide-azobenzene (GO-AZO) hybrid was investigated as a highly sensitive photoswitch. The internal short-range ordered crystalline structure of GO-AZO hybrid was advantageous to charge transfer. The AZO moieties on GO underwent a rapid trans-cis photoisomerization upon ultraviolet irradiation due to the electron interaction between AZO and GO. The GO-AZO hybrid film showed an enhanced reversible photoswitching performance with high on/off ratio of 8 and fast response time less than 500 ms. The high sensitivity of GO-AZO switch arises from the intramolecular donor-acceptor architecture with efficient charge transfer.
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Development of intelligent adaptable materials with unprecedented sensitivity that can mimic the tactile sensing functions of natural skin is a major driving force in the realization of artificial intelligence. Herein, we judiciously designed and synthesized a series of lauryl acrylate-based polymeric organogels with high transparency, mechanical adaptability, self-healing properties, and adhesive capability. Moreover, a robust capacitive sensor with high sensitivity (0.293 kPa-1) was developed by sandwiching the prepared soft, adaptable organogels between two tough conductive hydrogels and then used to monitor various human motions such as finger stretching, wrist bending, and throat movement during chewing. Interestingly, the resulting capacitive sensor could also function as prosthetic skin on a pneumatic soft artificial hand, enabling intelligent haptic perception. The research disclosed herein is expected to provide insights into the rational design of artificial human-like skins with unprecedented functionalities.
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Hidrogéis/química , Pele Artificial , Resinas Acrílicas/química , Adesivos , Inteligência Artificial , Humanos , Íons/química , Dispositivos Eletrônicos VestíveisRESUMO
As a key method to convert solar into chemical energy, photocatalytic water decomposition has garnered attention. Moreover, the development of graphene and graphene-like two-dimensional (2D) materials has brought fresh vitality in the field of photocatalysis. Here, we prepared two to four layers of GeTe nanosheets by ultrasonic-assisted liquid-phase exfoliation in argon and air, which we referred to as Ar-GeTe and O-GeTe, respectively. The photocatalytic hydrogen production potential of 2D GeTe was experimentally investigated for the first time. The results indicated that minimally layered GeTe samples are indirect-gap semiconductors with the GeTe band gap increasing after oxidation. All samples have suitable band positions that can drive photocatalytic water splitting into H2 under mild conditions, providing maximum hydrogen evolution rates of 1.13 mmol g-1 h-1 (Ar-GeTe) and 0.54 mmol g-1 h-1 (O-GeTe). With density functional theory computations, the structural stability of GeTe in air was discussed, revealing that oxygen atoms could easily combine with Ge to form a more stable structure, thus impacting the photocatalytic performance of 2D GeTe. Therefore, the light requirement and oxygen deficiency of the material give an advantage in the field of energy supply in space.
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The discovery of graphene and graphene-like two-dimensional materials has brought fresh vitality to the field of photocatalysis. Bandgap engineering has always been an effective way to make semiconductors more suitable for specific applications such as photocatalysis and optoelectronics. Achieving control over the bandgap helps to improve the light absorption capacity of the semiconductor materials, thereby improving the photocatalytic performance. This work reports two-dimensional -H/-OH terminal-substituted siligenes (gersiloxenes) with tunable bandgap. All gersiloxenes are direct-gap semiconductors and have wide range of light absorption and suitable band positions for light driven water reduction into H2, and CO2 reduction to CO under mild conditions. The gersiloxene with the best performance can provide a maximum CO production of 6.91 mmol g-1 h-1, and a high apparent quantum efficiency (AQE) of 5.95% at 420 nm. This work may open up new insights into the discovery, research and application of new two-dimensional materials in photocatalysis.
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Temperature-dependent modification is an effective way to reversibly tailor graphene's electronic properties. We present the reversible modification of a uniform monolayer nitrogen-doped graphene (NG) film by the formation and cleavage of temperature-dependent Se-N dynamic covalent bonds. The increasing binding energy in X-ray photoelectron spectroscopy (XPS) indicates that phenylselenyl bromine (PhSeBr) bonds with pyridinic N and pyrrolic N rather than graphitic N by accepting the lone pair of electrons. The temperature dependence of Raman spectra (the increasing D band and the shifts of the 2D band) and XPS spectra (Se 3d and N 1s) indicates that the Se-N dynamic covalent bond is gradually cleaved by treatment at increasing temperatures and is also recovered by the reversible modification. Field-effect transistors (FETs) based on Se-NG exhibit a temperature-dependent change from n-type to p-type conduction and tunable electron and hole mobilities owing to the reversible formation or cleavage of Se-N dynamic covalent bonds. This result opens up opportunities for reversibly controlling electrical properties of FETs by optimizing dynamic covalent bonds.
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Significant progress has been made to replace graphite anode materials with Li metal in next-generation Li ion batteries, called Li metal batteries (LMBs). However, the development of practical LMBs requires the suppression of Li dendrites. Owing to their ability to relax polarization, single-ion solid polymer electrolytes (SSPEs) are widely considered as an effective strategy for preventing dendrite generation. The novel SSPE membrane prepared in this work, which consists of a polymeric lithium salt modified with an electrolyte solvent, shows single-ion conducting behavior that results in the effective restriction of Li dendritic growth. The SSPE membrane delivers an ionic conductivity as high as 1.42 × 10-4 S cm-1 at room temperature. A LiFePO4 (LFP) coin cell assembled with the SSPE membrane shows excellent rate performance and outstanding cycling stability. In addition, the LFP flexible battery using the SSPE membrane exhibits good practicability and environmental adaptability.
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The breakthrough of nonprecious metal catalysts replacing platinum-based catalysts toward the oxygen reduction reaction (ORR) is extremely urgent for the development of high-efficiency energy conversation systems. Herein, a solution-processed condensation polymerization using cyanuric chloride and piperazine as the monomers was proposed for the synthesis of a nitrogen-rich covalent organic polymer (COP). High contents of precisely tailored pyridinic-N within the COP facilitate the formation of the Co/N coordination between Co ions and N species. As a result, the subsequent carbonization of the Co-coordinated COP led to the formation of the cobalt, nitrogen dual-doped porous carbon nanosheet-assembled flowers (Co/N-PCNF). The as-obtained Co/N-PCNF catalyst with a nearly 4-electron oxygen reduction pathway exhibits an excellent ORR catalytic activity with a half-wave potential of 0.835 V comparable to the commercial Pt/C catalysts (0.865 V). Most impressively, the Co/N-PCNF catalyst displays a long-term stability and a much better resistance to methanol than the Pt/C catalyst because of its high surface area, well-defined porous structure, and homogeneous distributions of active sites within the carbon matrix. Therefore, this work establishes an operating rule for tailored synthesis of COP-derived nonprecious metal catalysts offering high activity for the ORR in electrochemical energy conversations.