Superhydrophobic, mechanically durable coatings for controllable light and magnetism driven actuators

Fabrication of Superhydrophobic Surfaces from Laser-Induced Graphene and Their Photothermally Driven Properties

Conventional LIG preparation mostly relies on the ablation process of a CO2 laser on a polyimide (PI) substrate but is limited by the sensitivity of the laser parameters, which is prone to PI film deformation, non-uniformity of the process, or LIG surface breakage problems. In this study, we present a new method to fabricate superhydrophobic laser-induced graphene (SH-LIG) surfaces by immobilizing the polyimide (PI) film on the copper sheet, which enables uniform laser processing (single pass laser etching) over a wider range of microsecond laser parameters (10.5-19.5 W). Subsequently, the SH-LIG was obtained by vacuum-assisted immersion in stearic acid, resulting in a water contact angle greater than 150°, roll angle stabilized at 6°, and hydrophobic stability at a high temperature of 90 °C. Analysis by Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) showed that the LIG fabricated at optimal power (19.5 W) had a more developed C sp2 network (I2D/IG ≈ 0.5) and pore structure, which significantly improved the photothermal conversion efficiency (up to 252 °C in air and 180 °C on water). On this basis, a simple micro-driver based on SH-LIG was designed. Experiments showed that the maximum velocity of the SH-LIG boat can reach an adjustable propulsion velocity of 45.6 mm/s (related to the laser processing power and the intensity of the driving light), which is 132% higher than that of the LIG boat. This work provides insights into the preparation of high-quality LIG and their application in photothermally driven micro actuators, highlighting the synergies between structural optimization, surface engineering, and photothermal performance.

Cooperative Magnetic Interfacial Microrobot Couple for Versatile Non-Contact Biomedical Applications

Magnetic interfacial microrobots are increasingly recognized as a promising approach for potential biomedical applications ranging from electronic functionalization to minimally invasive surgery and targeted drug delivery. Nevertheless, existing research faces challenges, including less cooperative interactions, contact-based cargo manipulation, and slow transport velocity. Here, the cooperative magnetic interfacial microrobot couple (CMIMC) is proposed to address the above challenges. The CMIMC can be maneuvered by a single magnet and readily switched between capture and release states. By leveraging cooperative interactions and meticulous engineering of capillary forces through shape design and surface treatment, the CMIMC demonstrates the ability to perform non-contact cargo manipulation. Using the synergy of preferred magnetization directions and magnetic field distribution, along with optimization of the resistance-reducing shape, the CMIMC significantly enhances the cargo transport velocity, reaching 12.2 body length per second. The studies demonstrate various biomedical applications like targeted drug delivery and myomectomy, paving the way for the broad implementation of interfacial microrobots in biomedical fields.

Study on Intelligent Bionic Superhydrophobic Material and its Oil-Water Separation Mechanism

Marine oil spills and improper disposal of daily oil usage have posed significant threat to ecological environments and human health due to rapid industrial development. In this study, an environmentally friendly, simple process and high-performance Fe3O4@SiO2@Polymethyl methacrylate (PMMA)-based smart bionic superhydrophobic oil-absorbing material was developed for effectively collecting and removing oil pollutants from water. By studying the effects of Fe3O4 particle size, polydimethylsiloxane (PDMS) concentration, and heating time on the superhydrophobicity of the materials, the directional regulation of superhydrophobicity and oil-water separation performance of Fe3O4@SiO2@PMMA@PDMS materials was realized. The results showed that the material exhibited optimal performance when the Fe3O4 particle size combination was 20/500 nm/1 μm, the mass ratio of PDMS to Fe3O4@SiO2@PMMA was 7 : 1, and it was heated at 350°C for 1 minute. The coating achieved an apparent contact angle (APCA) of 158.7° and a rolling angle as low as 4.9°. This coating not only remained superhydrophobic after a 21 m abrasion test and 288 h immersion in acid, alkali, salt, and high-temperature solutions, but also efficiently separated oil-water mixtures and water-in-oil emulsions, and the separation efficiency for oil-water mixtures of trichloromethane, dichloromethane and bromomethane was over 99.78 %, and that for water-in-oil emulsions was over 98.34 %. Furthermore, the superhydrophobic magnetic polyurethane (SFPU) sponge prepared using Fe3O4@SiO2@PMMA not only exhibited excellent oil-absorbing capacity (11-28 g/g), but also realized precise oil absorption at multiple sites by magnetic conduction. In the actual oily wastewater test, the oil-water separation efficiency of the sponge reached 90.58 % and the oil absorption capacity reached 17.03 g/g. This efficient oil-water separation performance as well as oil adsorption capacity comes from the fact that the nonpolar molecules (e. g., -CH3) generated by the hydrolysis of PDMS can produce van der Waals adsorption with oil substances, while the excellent micro-nanostructure of the coating surface greatly increases the contact area between oil droplets and the coating, which can make them adsorb or pass through quickly. This multifunctional coating and sponge had immense application potential in fields like offshore oil spill treatment, organic pollution control in water bodies.

Kinetic monitoring of molecular interactions during surfactant-driven self-propelled droplet motion by high spatial resolution waveguide sensing

HYPOTHESIS

Self-driven actions, like motion, are fundamental characteristics of life. Today, intense research focuses on the kinetics of droplet motion. Quantifying macroscopic motion and exploring the underlying mechanisms are crucial in self-structuring and self-healing materials, advancements in soft robotics, innovations in self-cleaning environmental processes, and progress within the pharmaceutical industry. Usually, the driving forces inducing macroscopic motion act at the molecular scale, making their real-time and high-resolution investigation challenging. Label-free surface sensitive measurements with high lateral resolution could in situ measure both molecular-scale interactions and microscopic motion.

EXPERIMENTS

We employ surface-sensitive label-free sensors to investigate the kinetic changes in a self-assembled monolayer of the trimethyl(octadecyl)azanium chloride surfactant on a substrate surface during the self-propelled motion of nitrobenzene droplets. The adsorption-desorption of the surfactant at various concentrations, its removal due to the moving organic droplet, and rebuilding mechanisms at droplet-visited areas are all investigated with excellent time, spatial, and surface mass density resolution.

FINDINGS

We discovered concentration dependent velocity fluctuations, estimated the adsorbed amount of surfactant molecules, and revealed multilayer coverage at high concentrations. The desorption rate of surfactant (18.4 s-1) during the microscopic motion of oil droplets was determined by in situ differentiating between droplet visited and non-visited areas.

Light-Driven Microrobots for Targeted Drug Delivery

As a new micromanipulation tool with the advantages of small size, flexible movement and easy manipulation, light-driven microrobots have a wide range of prospects in biomedical fields such as drug targeting and cell manipulation. Recently, microrobots have been controlled in various ways, and light field has become a research hotspot by its advantages of noncontact manipulation, precise localization, fast response, and biocompatibility. It utilizes the force or deformation generated by the light field to precisely control the microrobot, and combines with the drug release technology to realize the targeted drug application. Therefore, this paper provides an overview of light-driven microrobots with drug targeting to provide new ideas for the manipulation of microrobots. Here, this paper briefly categorizes the driving mechanisms and materials of light-driven microrobots, which mainly include photothermal, photochemical, and biological. Then, typical designs of light-driven microrobots with different driving mechanisms and control strategies for multiple physical fields are summarized. Finally, the applications of microrobots in the fields of drug targeting and bioimaging are presented as well as the future prospects of light-driven microrobots in the biomedical field are demonstrated.

Superhydrophobic Solar-to-Thermal Materials Toward Cutting-Edge Applications

Solar-to-thermal conversion is a direct and effective way to absorb sunlight for heat via the rational design and control of photothermal materials. However, when exposed to water-existed conditions, the conventional solar-to-thermal performance may experience severe degradation owing to the high specific heat capacity of water. To tackle with the challenge, the water-repellent function is introduced to construct superhydrophobic solar-to-thermal materials (SSTMs) for achieving stable heating, and even, for creating new application possibilities under water droplets, sweat, seawater, and ice environments. An in-depth review of cutting-edge research of SSTMs is given, focusing on synergetic functions, typical construction methods, and cutting-edge potentials based on water medium. Moreover, the current challenges and future prospects based on SSTMs are also carefully discussed.

Light and Magnetism Orchestrating Aquatic Pollutant-Degradation Robots in Programmable Trajectories

Interfacial floating robots have promising applications in carriers, environmental monitoring, water treatment, and so on. Even though, engineering smart robots with both precisely efficient navigation and elimination of water pollutants in long term remains a challenge, as the superhydrophobicity greatly lowers resistance for aquatic motion while sacrificing chemical reactivity of the surface. Here, a pollutant-removing superhydrophobic robot integrated with well-assembled iron oxide-bismuth sulfide heterojunction composite minerals, which provide both light and magnetic propulsion, and the ability of catalytic degradation, is reported. The motion velocity of the robot reaches up to 51.9 mm s-1 within only 300 ms of acceleration under the orchestration of light, and brakes rapidly (≈200-300 ms) once turn off the light. And magnetism extends the robot to work in broad range of surface tensions in any programmable trajectory. Besides, purification of polluted water is efficiently achieved in situ and the degradation efficiency exhibits eightfold enhancements under the effect of light-triggered photothermal behavior coupled with magnetic induction, overcoming the dilemma of efficient motion with catalytic superhydrophobicity. This strategy developed here provides guidelines for the explorations of high-performance smart devices.

Photothermal Performance of Lignin-Based Nanospheres and Their Applications in Water Surface Actuators

In this study, the photothermal performance of lignin-based nanospheres was investigated. Subsequently, a photothermal actuator was prepared using lignin-based carbon nanospheres (LCNSs). The results demonstrated that LCNSs exhibited an impressive photothermal conversion efficiency of up to 83.8%. This extreme efficiency significantly surpasses that of lignin nanospheres (LNSs) and covalently stabilized LNSs (HT-LNSs). As a structural material, a hydrophobic coating was effectively engineered by LCNSs on the filter paper, achieving a water contact angle of 151.9° ± 4.6°, while maintaining excellent photothermal effects (with a temperature increment from room temperature to 138 °C in 2 s). When employing hydrophobic filter paper as the substrate for the photothermaldriven actuator, under the influence of a 1.0 W/cm2 power-density NIR laser, the material exhibited outstanding photothermal actuation, achieving speeds up to 16.4 mm/s. In addition, the direction of motion of the actuator can be adjusted in accordance with the location of the NIR light irradiation. This study offers valuable perspectives on the application of LNSs for highvalue applications and the development of innovative photothermal-driven actuators.

Study on the Mechanism of Rapid Oil-Water Separation by a Fe3 O4 @PMMA@PDMS Intelligent Superhydrophobic Micro/Nanorobot

We prepared an environmentally friendly intelligent Fe3 O4 @PMMA@PDMS superhydrophobic oil-absorbing material with simple process and excellent performance, and investigated the effects of different particle sizes of Fe3 O4 , different concentrations of PDMS, and different heating times on the superhydrophobicity of the coating. The best performance of the coating was achieved at a particle size combination of 20/500 nm for Fe3 O4 , a PDMS to Fe3 O4 @PMMA mass ratio of 6 : 1, and a heating time of 2 min at 400 °C. H2-SPSS coating not only has excellent superhydrophobicity, abrasion resistance, self-cleaning property, and chemical corrosion, but also has good flux and efficiency for separating oil-water mixture, with fluxes of 40,540, 32,432, and 37,027 Lm-2 h-1 for trichloromethane, dichloromethane and bromoethane, respectively, and separation efficiencies of 99.78 %, 99.74 % and 99.73 %, respectively. In addition, we also prepared a superhydrophobic magnetic polyurethane (SPPU) sponge using Fe3 O4 @PMMA@PDMS, which not only has a good oil absorption capacity of 18-44 g/g for different oil substances, it can also move directionally by magnet attraction and absorb oil along a fixed path. Under the control of the magnet, SPPU completes the whole oil absorption process in only 4 s, showing excellent oil absorption and intelligence.

Carbon nanofiber reinforced carbon aerogels for steam generation: Synergy of solar driven interface evaporation and side wall induced natural evaporation

Solar-based interface evaporation (SIE) is a green, efficient and cost-effective technique to harvest fresh water. 3D solar evaporators show their unique advantages in gaining energy from environment and hence possess a higher evaporation rate than 2D evaporators. However, much effort is still required to develop mechanically robust and superhydrophilic 3D evaporators with strong water transportation capability and salt-rejection performance, and at the same time reveal how they gain energy from environment via the natural evaporation. In this work, a novel carbon nanofiber reinforced carbon aerogel (CNFA) is prepared for the SIE. The CNFA has a high light absorption up to 97.2% and outstanding photothermal conversion performance. The heteroatom doping and hierarchically porous structure endow the CNFA with superhydrophilicity and thus powerful water transportation capability and salt rejection performance. Benefiting from synergy of the SIE and side wall induced natural evaporation, the CNFA evaporator exhibits a high evaporation rate and efficiency (as high as 3.82 kg m^-2h^-1 and 95.5%, respectively) with long-term stability and durability. The CNFA can also work normally in high-salinity and corrosive seawater. This study demonstrates a new method to fabricate all-carbon aerogel solar evaporators and provides insights for the effective thermal management during the interface evaporation.

Green fabrication of durable foam composites with asymmetric wettability by an emulsion spray-coating method for photothermally induced crude oil cleanup

Chemical spills, especially oil spills, are becoming an increasingly serious environmental issue. It remains a challenge to develop green techniques to prepare mechanically robust oil-water separation materials, especially those capable of separating high-viscosity crude oils. Herein, we propose an environmentally friendly emulsion spray-coating method to fabricate durable foam composites with asymmetric wettability for oil-water separation. After the emulsion, composed of acidified carbon nanotubes (ACNTs), polydimethylsiloxane (PDMS) and its curing agent, is sprayed onto melamine foam (MF), water in the emulsion is first evaporated, while PDMS and ACNTs are finally deposited on the foam skeleton. The foam composite exhibits gradient wettability and turns from superhydrophobicity of the top surface (the water contact angle reaches as high as 155.2°) to hydrophilicity of the interior region. The foam composite can be used for the separation of oils with different densities and has a 97% separation efficiency for chloroform. In particular, the photothermal conversion-induced temperature rise can reduce the oil viscosity and complete the high-efficiency cleanup of crude oil. This emulsion spray-coating technique and asymmetric wettability show promise for the green and low-cost fabrication of high-performance oil/water separation materials.

Solid-phase extraction based on PDMS/ionic liquid sponge followed by gas chromatography-mass spectrometry for rapid and sensitive determination of volatile components in lavender

INTRODUCTION

Due to the complexity and the low concentrations of volatile components in aromatic plants, sample pretreatment is an important step in the whole analytical procedure.

OBJECTIVE

This study aimed to propose a novel, sensitive and fast approach to determine the volatile components in lavender.

METHODS

The 1-butyl-3-(propyltrimethoxysilane)imidazolium chloride ([BPtmsim]Cl) ionic liquid was introduced onto the surface of polydimethylsiloxane (PDMS) to prepare a novel PDMS/[BPtmsim]Cl sponge with large surface area, good sorption performance, and reusability. A solid-phase extraction method was developed based on PDMS/[BPtmsim]Cl sponge combined with gas chromatography-mass spectrometry (GC-MS).

RESULTS

The effects of the various experimental parameters on the extraction efficiency were investigated. The optimal conditions were [BPtmsim]Cl amount of 0.3 g, 1:4 as the mass ratio of PDMS/[BPtmsim]Cl to lavender sample, microwave power of 700 W, microwave time of 10 min, and n-hexane as the desorption solvent. The method validation results showed good linearity (10-800 μg/ml), high correlation coefficient (R²  ≥ 0.9991), low limits of detection (1.73-2.50 ng/μl), and limits of quantification (4.10-5.11 ng/μl). The interday and intraday precision with relative standard deviation (RSD) values were below 1.93% and 4.71%, respectively. Under the optimal extraction conditions, 16 lavender samples from three different species were analysed and a total of 57 volatile compounds were identified. The correlation between different species of lavender and volatile components was explored using principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA).

CONCLUSION

The results showed that PDMS/[BPtmsim]Cl extraction is a rapid, highly efficient, and sensitive technique for the determination of volatile components in complex plant samples.

Stretchable, durable and asymmetrically wettable nanofiber composites with unidirectional water transportation capability for temperature sensing

The one-way transportation of liquids plays an important role in smart and wearable electronics. Here, we report an asymmetric nanofibrous membrane (ANM) with unidirectional water transport (UWT) capability by integrating one superhydrophilic MXene/Chitosan/Polyurethane (PU) nanofiber membrane (MCPNM) and one ultrathin hydrophobic PU/Polyvinylpyrrolidone (PVP) layer with a "bead-on-string" structure. The UWT performance shows long-term stability and can be well maintained during the cyclic stretching, abrasion and ultrasonic washing tests. The ANM exhibits negative temperature coefficient and is served as a temperature sensor to monitor the temperature variation of the environment, which can provide efficient alarm signals in a hot or cold condition. When attached on person's skin, the ANM displays a unique anti-gravity UWT behavior. The stretchable, wearable and multi-functional nanofibrous composite membrane with an asymmetric wettability shows potential applications in flexible and wearable electronics, health monitoring, etc.

Versatile Melanin-Like Coatings with Hierarchical Structure toward Personal Thermal Management, Anti-Icing/Deicing, and UV Protection

Superhydrophobic photothermal coatings are promising for multifunctional applications due to the efficient use of solar energy, but the current challenge is to seek one easy-to-prepare material with high photothermal performance. Herein, inspired by mussel adhesion and lotus leaf surfaces, we developed superhydrophobic photothermal coatings with hierarchical structure by depositing melanin-like polydopamine (PDA) and dip-coating polydimethylsiloxane (PDMS)/hydrophobic fumed silica (SiO₂) sequentially. Benefitting from the efficient photothermal conversion performance of PDA, the coated fabric can rapidly warm up to 100 °C under 100 mW/cm² sun irradiation. Meanwhile, the coatings show excellent superhydrophobic properties (WCA of 163°), which not only prevent the adhesion of the contaminant from maintaining a long-term and efficient photothermal performance but also help the fabric to own outstanding passive anti-icing and active deicing performances. Furthermore, the superhydrophobic properties of the coatings can be maintained after sandpaper abrasion, repeat tape-peeling, and ultrasonication. In addition, superior UV protection of the coatings can meet the long-term service conditions under outdoor sunlight. The PDA-based superhydrophobic photothermal coatings are believed to inspire new strategies for solar-driven multifunctional applications such as personal thermal management, anti-icing/deicing of variously shaped components, photothermal antibacterial, and so on.

Flexible and Stretchable Carbon-Based Sensors and Actuators for Soft Robots

In recent years, the emergence of low-dimensional carbon-based materials, such as carbon dots, carbon nanotubes, and graphene, together with the advances in materials science, have greatly enriched the variety of flexible and stretchable electronic devices. Compared with conventional rigid devices, these soft robotic sensors and actuators exhibit remarkable advantages in terms of their biocompatibility, portability, power efficiency, and wearability, thus creating myriad possibilities of novel wearable and implantable tactile sensors, as well as micro-/nano-soft actuation systems. Interestingly, not only are carbon-based materials ideal constituents for photodetectors, gas, thermal, triboelectric sensors due to their geometry and extraordinary sensitivity to various external stimuli, but they also provide significantly more precise manipulation of the actuators than conventional centimeter-scale pneumatic and hydraulic robotic actuators, at a molecular level. In this review, we summarize recent progress on state-of-the-art flexible and stretchable carbon-based sensors and actuators that have creatively added to the development of biomedicine, nanoscience, materials science, as well as soft robotics. In the end, we propose the future potential of carbon-based materials for biomedical and soft robotic applications.

Towards Online Ageing Detection in Transformer Oil: A Review

Transformers play an essential role in power networks, ensuring that generated power gets to consumers at the safest voltage level. However, they are prone to insulation failure from ageing, which has fatal and economic consequences if left undetected or unattended. Traditional detection methods are based on scheduled maintenance practices that often involve taking samples from in situ transformers and analysing them in laboratories using several techniques. This conventional method exposes the engineer performing the test to hazards, requires specialised training, and does not guarantee reliable results because samples can be contaminated during collection and transportation. This paper reviews the transformer oil types and some traditional ageing detection methods, including breakdown voltage (BDV), spectroscopy, dissolved gas analysis, total acid number, interfacial tension, and corresponding regulating standards. In addition, a review of sensors, technologies to improve the reliability of online ageing detection, and related online transformer ageing systems is covered in this work. A non-destructive online ageing detection method for in situ transformer oil is a better alternative to the traditional offline detection method. Moreover, when combined with the Internet of Things (IoT) and artificial intelligence, a prescriptive maintenance solution emerges, offering more advantages and robustness than offline preventive maintenance approaches.

Multistimuli-Responsive Hydroplaning Superhydrophobic Microrobots with Programmable Motion and Multifunctional Applications

Superhydrophobic microrobots that can swim efficiently and rapidly on water under the action of external stimuli have attracted significant research attention for various applications. However, most studies on superhydrophobic microrobots have focused on single-stimulus driving modes, which limit the motion and functional applications of microrobots in complex aquatic environments. Therefore, multistimuli-responsive superhydrophobic microrobots that are capable of drifting rapidly on water through light, magnetic, and chemical control were developed in this study. The stability and environmental adaptability of the microrobots were systematically investigated. The microrobots achieved programmable trajectory motion on water, particularly complex motions such as circular, spiral, and helical movements under the coupled influence of chemical and magnetic fields. Importantly, the motion and control of multimicrorobots can be realized by combining control methods. Under the action of light and magnetic field, multimicrorobots could realize cooperative movement and completed the transportation of cargo. Additionally, broad multifunctional applications of the microrobots were explored in terms of oil spill recovery and solution mix. This study provides a method for the preparation and development of superhydrophobic microrobots with multistimuli-responsive characteristics.

A versatile "3M" methodology to obtain superhydrophobic PDMS-based materials for antifouling applications

Fouling, including inorganic, organic, bio-, and composite fouling seriously affects our daily life. To reduce these effects, antifouling strategies including fouling resistance, release, and degrading, have been proposed. Superhydrophobicity, the most widely used characteristic for antifouling that relies on surface wettability, can provide surfaces with antifouling abilities owing to its fouling resistance and/or release effects. PDMS shows valuable and wide applications in many fields, and due to the inherent hydrophobicity, superhydrophobicity can be achieved simply by roughening the surface of pure PDMS or its composites. In this review, we propose a versatile "3M" methodology (materials, methods, and morphologies) to guide the fabrication of superhydrophobic PDMS-based materials for antifouling applications. Regarding materials, pure PDMS, PDMS with nanoparticles, and PDMS with other materials were introduced. The available methods are discussed based on the different materials. Materials based on PDMS with nanoparticles (zero-, one-, two-, and three-dimensional nanoparticles) are discussed systematically as typical examples with different morphologies. Carefully selected materials, methods, and morphologies were reviewed in this paper, which is expected to be a helpful reference for future research on superhydrophobic PDMS-based materials for antifouling applications.

A Light-Powered Triboelectric Nanogenerator Based on the Photothermal Marangoni Effect

The photothermal Marangoni effect enables direct light-to-work conversion, which is significant for realizing the self-propulsion of objects in a noncontact, controllable, and continuous manner. Many promising applications have been demonstrated in micro- and nanomachines, light-driven actuators, cargo transport, and gear transmission. Currently, the related studies about photothermal Marangoni effect-induced self-propulsion, especially rotational motions, remain focused on developing the novel photothermal materials, the structural designs, and the controllable self-propulsion modes. However, extending the related research from the laboratory practice to practical application remains a challenge. Herein, we combined the photothermal Marangoni effect-induced self-propulsion with the triboelectric nanogenerator technology for sunlight intensity determination. Photothermal black silicon, superhydrophobic copper foam with drag-reducing property, and triboelectric polytetrafluoroethylene film were integrated to fabricate a triboelectric nanogenerator. The photothermal-Marangoni-driven triboelectric nanogenerator (PMD-TENG) utilizes the photothermal Marangoni effect-induced self-propulsion to realize the relative motion between the triboelectric layer and the electrode, converting light into electrical signals, with a peak value of 2.35 V. The period of the output electrical signal has an excellent linear relationship with the light intensity. The accessible electrical signal generation strategy proposed here provides a new application for the photothermal Marangoni effect, which could further inspire the practical applications of the self-powered system based on the photothermal Marangoni effect, such as intelligent farming.

Mechanically robust Janus nanofibrous membrane with asymmetric wettability for high efficiency emulsion separation

Water pollution caused by oil leakage or oily sewage has seriously threatened the ecological environment and human health. It remains a tough task for scientists to develop versatile materials to purify different kinds of oily wastewater. In this study, we propose a facile "carbon nanotubes (CNTs) decoration and nanofibrous membrane integration" method to prepare a mechanical robust Janus membrane (JM) composed of a superhydrophilic nanofiber composite layer and a hydrophobic nanofiber composite layer. The asymmetric wettability can be controlled by tuning the thickness of the hydrophobic layer. The nanofiber composite in both two layers possesses a core-shell structure, guaranteeing the excellent flexibility and stretchability of the JM. In addition, the strong interfacial compatibility between the two layers ensures the stability and durability of the JM even after multiple stretching. More importantly, the JM could realize on-demand separation of different kinds of oily wastewater with high separation flux and separation efficiency, including oil/water mixtures with different oil densities, oil-in-water emulsions and water-in-oil emulsions. Furthermore, the JM exhibits cycling stability and long-term serviceability for the emulsion separation. The mechanically robust and stretchable JM has promising applications in purification of various oil contaminated wastewater.

Superhydrophobic, electrically conductive and multifunctional polymer foam composite for chemical vapor detection and crude oil cleanup

The leakage of chemicals (either vapors or liquids) severely threatens the environment and even people's health. It remains a great challenge to develop multifunctional and durable materials that can not only detect the chemical vapors but also clean up the liquid chemicals especially high viscous crude oil. Here, a superhydrophobic and conductive foam composite (SCFC) is prepared by decorating carbon black nanoparticles (CBNPs) onto the skeleton of the pre-swollen polymer foam under the assistance of ultrasonication. The CBNPs are firmly embedded onto the skeleton surface, exhibiting a strong interfacial adhesion and hence excellent surface stability and durability. The SCFC possesses stable vapor sensing behavior and can detect various chemical vapors with a low detection limit and good cycling performance. When used for oil/water separation, the SCFC has large oil adsorption capacity for different oils with excellent reusability. Also, the outstanding photo-thermal conversion performance of the SCFC can be used to significantly reduce the oil viscosity and hence realize efficient cleanup of the crude oil. The multifunctional SCFC has promising applications in the field of environment protection, flexible electronics, etc.

Interface-engineered reduced graphene oxide assembly on nanofiber surface for high performance strain and temperature sensing

Conductive polymer nanofiber composites (CPNCs) based wearable sensing electronics have aroused great attention of scientists in recent years. However, it is still difficult to obtain CPNCs with good water proof, excellent durability, and multiple sensing performance. Herein, we develop a multifunctional CPNC with a wrinkled reduced graphene oxide (RGO) shell and polymer nanofiber core, which is prepared by ultrasonication induced decoration of RGO onto the pre-stretched polyurethane (PU) nanofibers, followed by the release of the strain. The RGO assembly with a wrinkled structure not only greatly increases the surface roughness and thus the hydrophobicity but also enhances the strain sensing sensitivity (with a gauge factor of 154.8 in the strain range of 85%-100%) of the nanofibrous membrane. The obtained CPNC strain sensor also shows excellent sensing durability (over 1000 cycles) and can be used for body motion monitoring. The CPNC shows a negative temperature coefficient effect, which holds promising applications in high performance temperature sensors.