A Wax-Elastomer Superwetting Membrane with Controllable Permeability: Toward Separating a Crude Oil-in-Water Emulsion from an Oil Field.

Smart superwetting membranes with finely tunable properties have attracted increased attention recently. However, they mostly focus on controllable wettability rather than controllable permeability. Also, the oil/water separation performance is usually tested with laboratory-simulated samples, making it hard for the materials to meet practical applications. Herein, we fabricate thermally responsive superwetting membranes with wax, polystyrene-B-poly(ethylene-ran-butylene)-B-polys (SEBS, a kind of elastomer), and polydopamine (PDA) to realize emulsion separation with controllable permeability. Benefiting from the elasticity of SEBS and the fluidity difference of wax at different temperatures, the pore size of the membrane could be readily tuned, resulting in different permeability. The separation flux is 0 at ambient temperature (pore size 0.394 µm) and is over 100 L m-2 h-1 at a high temperature (pore size 0.477 µm). The membrane could realize the separation of simulated oil-in-water emulsions with efficiency above 99.4%. Furthermore, it successfully achieved crude oil-in-water emulsion separation from the oil field with oil residues of less than 300 mg L-1 in the temperature range of 60-80 °C, which is the actual working temperature adopted in industrial production. Such a polydopamine/wax-SEBS modified membrane with unprecedented controllable permeability can promote the development of the emulsion treatment field and provide a new direction for designing smart superwetting materials.

Superwetting Patterned Membranes with an Anisotropy/Isotropy Transition: Towards Signal Expression and Liquid Permeation.

Superwetting membranes with responsive properties have attracted heightened attention because of their fine-tunable surface wettability. However, their functional diversity is severely limited by the "black-or-white" wettability transition. Herein, we describe a coating strategy to fabricate multifunctional responsive superwetting membranes with SiO2 /octadecylamine patterns. The adjustable patterns in the responsive region are the key factor for functional diversity. Specifically, the coated part of the membrane displayed a superhydrophobicity/superhydrophilicity transition at different pH values, whereas the uncoated part exhibited invariant superhydrophilicity. On the basis of this anisotropy/isotropy transition, the membranes can serve as either responsive permeable membranes or signal-expression membranes, thus enabling the responsive separation and permeation of liquids with satisfactory separation efficiency (>99.90 %) and flux (ca. 60 L m-2 h), as well as real-time liquid signal expression with alterable signals.

PG-PEI-Ag NPs-Decorated Membrane for Pretreatment of Laboratory Wastewater: Simultaneous Removal of Water-Insoluble Organic Solvents and Water-Soluble Anionic Organic Pollutants.

Generally, waste liquid in laboratory can be roughly classified into organic wastewater and inorganic wastewater. However, in some experiments, organic phase and water phase are inevitably mixed together, leaving the postclassification and disposal intractable. Traditionally, we used methods like distillation and extraction to separate these two phases, however, always consuming significant amounts of labor and time and meanwhile having an unsatisfactory separation efficiency. Here, we proposed an improved processing method with a propyl gallate (PG)-polyethyleneimine (PEI)-Ag nanoparticles (NPs)-decorated membrane, possessing the special wettability designed for organic and water phase separation. Accordingly, various kinds of organic solvents/water mixtures were tested, where the PG-PEI-Ag NPs-decorated membrane was used like a common filter paper, fixed onto the funnel of the waste liquid barrel. Afterward, the two phase mixtures were poured onto the membrane; as a result, the organic phase was blocked above while the water phase was left below. All kinds of organic solvents/water mixtures showed higher than 99.90% removal efficiency. Besides, the membrane can remove water-soluble anionic organic molecules through electrostatic interaction. Thus, along the phase separation, anionic organic molecules in water can be removed simultaneously. This pretreatment of lab wastewater with the PG-PEI-Ag NPs-decorated membrane is simple and efficient, relieving the pressure of postcollection and disposal to some extent.

Polymer-Decorated Filter Material for Wastewater Treatment: In Situ Ultrafast Oil/Water Emulsion Separation and Azo Dye Adsorption.

Aiming to realize the wastewater treatment of various pollutants simultaneously, a dual-functional poly(ether amine)-polydopamine (PEA-PDA)-modified filter material was fabricated in this work for in situ separation of stable oil-in-water emulsion and adsorption of anionic azo dyes. PEA and PDA could be copolymerized via the Michael addition reaction on a polyurethane sponge substrate firmly. The as-prepared filter shows superhydrophilic and underwater superoleophobic wettability. After being squeezed in a glass tube, the material could separate different kinds of stabilized oil-in-water emulsions with high flux and efficiency. Besides, the PEA-PDA copolymer endows the material with the ability to adsorb large amounts of anionic azo dyes during the separation of emulsions with good adsorption capacity. Moreover, adsorbed dyes in the filter material could be easily desorbed in base aqueous solution and the whole process is conducted under gravity without external aid. This dual-functional material shows great potential for the application in industrial field because of its ability for the complex wastewater treatment.

Thermo-Driven Controllable Emulsion Separation by a Polymer-Decorated Membrane with Switchable Wettability.

A thermoresponsive Poly(N-isopropylacrylamide) (PNIPAAm)-modified nylon membrane was fabricated via hydrothermal route. Combining rough structure, proper pore size, and thermoresponsive wettability, the membrane can separate at least 16 types of stabilized oil-in-water and water-in-oil emulsions at different temperatures. Below the LCST (ca. 25 °C), the material exhibits hydrophilicity and underwater superoleophobicity, which can be used for the separation of various kinds of oil-in-water emulsions. Above the LCST (ca. 45 °C), the membrane shows the opposite property with high hydrophobicity and superoleophilicity, and it can then separate stabilized water-in-oil emulsions. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions and the hydrothermal method is facile and low-cost. The membrane shows good potential in real situations such as on-demand oil-spill cleanup, industrial wastewater treatment, remote operation of oil/water emulsion separation units, and fuel purification.

Nanocomposite Deposited Membrane for Oil-in-Water Emulsion Separation with in Situ Removal of Anionic Dyes and Surfactants.

The decontamination of various pollutants including oils, organic dyes, and surfactants from water is an unprecedented issue throughout the world. A facile filtration process for in situ multifunctional water purification by employing a low-cost and easy-made catechol-polyethylenimine (PEI) nanocomposite deposited membrane has been designed. In combination with the intrinsic hydrophilicity of amino-rich groups, the resultant membrane possesses superhydrophilicity and underwater superoleophobicity, which is simultaneously advantageous for capturing anionic pollutants due to the electrostatic interaction. Such membrane can be successfully used for sundry surfactant-stabilized oil-in-water emulsions separation and pH-controllable removal of water-soluble dyes and the remaining surfactants at the same time. The excellent characteristics, i.e., fabrication protocol that is easy to scale up, better alkaline resistance, selectively controllable removal ability of anionic dyes, and surfactants with unaltered adsorption performance over 30 consecutive adsorption-desorption-washing cycles, will facilitate its versatility and practicability in environmental remediation and wastewater purification.

Highly Stretchable Composite Conductive Fibers (SCCFs) and Their Applications.

Stretchable composite conductive fibers (SCCFs) exhibit remarkable conductivity, stretchability, breathability, and biocompatibility, making them ideal candidates for wearable electronics and bioelectronics. The exploitation of SCCFs in electronic devices requires a careful balance of many aspects, including material selection and process methodologies, to address the complex challenges associated with their electrical and mechanical properties. In this review, we elucidate the conductive mechanism of SCCFs and summarize strategies for integrating various conductors with stretchable fibers, emphasizing the primary challenges in fabricating highly conductive fibers. Furthermore, we explore the multifaceted applications of SCCFs-based frameworks in wearable electronic devices. This review aims to emphasize the significance of SCCFs and offers insights into their conductive mechanisms, material selection, manufacturing technologies, and performance improvement. Hopefully, it can guide the innovative development of SCCFs and broaden their application potential.

Self-Powered Temperature Electronic Skin Based on Island-Bridge Structure and Bi-Te Micro-Thermoelectric Generator for Distributed Mini-Region Sensing.

Thermoelectric (TE) effect based temperature sensor can accurately convert temperature signal into voltage without external power supply, which have great application prospects in self-powered temperature electronic skin (STES). But the fabrication of stretchable and distributed STES still remains a challenge. Here, a novel STES design strategy is proposed by combining flexible island-bridge structure with BiTe-based micro-thermoelectric generator (µ-TEG). Furthermore, a 4 × 4 vertical temperature sensor array with good stretchability and distributed sensing property has been fabricated for the first time. The interfacial chemical bonds located between the rigid islands (µ-TEG) and the flexible substrate (polydimethylsiloxane, PDMS) endow the STES with excellent stretchability, and its sensing performance remains unchanged under 30% strain (the maximum strain of human skin). Moreover, the STES sensing unit possesses high sensitivity (729 µV K-1 ), rapid response time (0.157 s), and high spatial resolution (2.75 × 2.75 mm2 ). As a proof of concept, this work demonstrates the application of the STES in the detection of mini-region heat sources in various scenarios including noncontact spatial temperature responsing, intelligent robotic thermosensing, and wearable temperature sensing. Such an inspiring design strategy is expected to provide guidance for the design and fabrication of wearable self-powered temperature sensors.

Overview of Liquid Crystal Biosensors: From Basic Theory to Advanced Applications.

Liquid crystals (LCs), as the remarkable optical materials possessing stimuli-responsive property and optical modulation property simultaneously, have been utilized to fabricate a wide variety of optical devices. Integrating the LCs and receptors together, LC biosensors aimed at detecting various biomolecules have been extensively explored. Compared with the traditional biosensing technologies, the LC biosensors are simple, visualized, and efficient. Owning to the irreplaceable superiorities, the research enthusiasm for the LC biosensors is rapidly rising. As a result, it is necessary to overview the development of the LC biosensors to guide future work. This article reviews the basic theory and advanced applications of LC biosensors. We first discuss different mesophases and geometries employed to fabricate LC biosensors, after which we introduce various detecting mechanisms involved in biomolecular detection. We then focus on diverse detection targets such as proteins, enzymes, nucleic acids, glucose, cholesterol, bile acids, and lipopolysaccharides. For each of these targets, the development history and state-of-the-art work are exhibited in detail. Finally, the current challenges and potential development directions of the LC biosensors are introduced briefly.

A Dually Charged Membrane for Seawater Utilization: Combining Marine Pollution Remediation and Desalination by Simultaneous Removal of Polluted Dispersed Oil, Surfactants, and Ions.

Shortage of freshwater and deterioration of the marine environment have a serious effect on the human body and ecological environment. Here, we demonstrated a facile way to prepare a multiple-target superwetting porous material to obtain available water without cumbersome steps. Through the facile immersion and hydrothermal method, a charge-enhanced membrane material combining superwettability, electrostatic interaction, and the steric effect is prepared. Such a material breaks through the limitations of single size sieving and has a universal effect on different kinds of contaminants with accurate wettability manipulation and fluid separation control. The protonation and deprotonation of active carboxyl groups at the novel created solid/liquid interface facilitate the surface wettability and flux transition, which will bring out superior continuous separation and surface lubrication control.

Universal and tunable liquid-liquid separation by nanoparticle-embedded gating membranes based on a self-defined interfacial parameter.

Superwetting porous membranes with tunable liquid repellency are highly desirable in broad domains including scientific research, chemical industry, and environmental protection. Such membranes should allow for controllable droplet bouncing or spreading, which is difficult to achieve for low surface energy organic liquids (OLs). Here we develop an interfacial physical parameter to regulate the OL wettability of nanoparticle-embedded membranes by structuring synergistic layers with reconfigurable surface energy components. Under the tunable solid-liquid interaction in the aggregation-induced process, the membranes demonstrate positive/negative liquid gating regularity for polar protic liquids, polar aprotic liquids, and nonpolar liquids. Such a membrane can be employed as self-adaptive gating for various immiscible liquid mixtures with superior separation efficiency and permeation flux, even afford successive achievement of high-performance in situ extraction-back extraction coupling. This study should provide distinctive insights into intrinsic wetting behaviors and have pioneered a rational strategy to design high-performance separation materials for diverse applications.

A bifunctional ß-MnO2 mesh for expeditious and ambient degradation of dyes in activation of peroxymonosulfate (PMS) and simultaneous oil removal from water.

Dual functional membranes that can simultaneously remove water-insoluble oil and degrade water-soluble dyes have received considerable attention. Nevertheless, there remain arduous challenges due to the critical restriction of slow degradation rate and the heavy dependence on external stimuli like light, electricity or heat. Herein, we report a superwetting and rapidly catalytic ß-MnO2 mesh prepared by one-step hydrothermal method. In activation of peroxymonosulfate (PMS), this ß-MnO2 mesh can expeditiously degrade dyes without any external stimuli and simultaneously remove oils. The removal efficiencies were all > 99% and the filtrates were proved eco-friendly through leaching test and toxic experiment. Furthermore, a mechanism on the excellent catalytic ability of ß-MnO2 mesh was proposed, i.e. H+ was immobilized in 1 × 1 tunnel of ß-MnO2, which made the mesh surface a positive zeta potential and attract more negative sulfate radicals, as a result inducing an improved degradation efficiency. Therefore, we anticipate this bifunctional and ingenious ß-MnO2 mesh can contribute a lot to prompt and mild sewage purifications.

Peanut Leaf-Inspired Hybrid Metal-Organic Framework with Humidity-Responsive Wettability: toward Controllable Separation of Diverse Emulsions.

Damage to the responsive superwetting material by external stimuli during the responsive process has been a ticklish question in recent years. We overcome this barrier by imitating a peanut leaf and designing a humidity-responsive MIL-100 (Fe)/octadecylamine-coated stainless steel mesh (HR-MOS). Such a material shows superhydrophilicity when ambient humidity is higher than saturated humidity, while it shows superhydrophobicity and high adhesion to water when ambient humidity is lower than saturated humidity. The peanut leaf-like two-level nanostructure of MIL-100 (Fe) is speculated as the principal factor to bring about the binary synergy wettability of the material. Accordingly, the material can realize humidity-controlled separation of at least 12 types of emulsions along with satisfactory durability. The responsive condition of the material is mild and green, which does lower damage to the material and environment. This strategy is the first to realize humidity-responsive wettability transition and provides a novel approach for manually controlled environmental protection.

Aminoazobenzene@Ag modified meshes with large extent photo-response: towards reversible oil/water removal from oil/water mixtures.

Photo-responsive materials with superwetting properties, especially in the azo-based class, have been used in water treatment because of their smart performance on wettability changes. However, their transformation extent in wettability has always troubled researchers. Here, we modified nano-Ag pine needles and aminoazobenzene (AABN) on polydopamine (PDA) pre-treated porous meshes, realizing a large-extent reversible photo-responsive wettability transformation from highly hydrophobic to highly hydrophilic. The contact angle is about 150.0° after being exposed to visible light, and is about 10.0° under 365 nm UV light. Accordingly, the modified mesh can achieve photo-responsive removal between oil and water from oil/water mixtures. This facile and universal approach based on trans-cis isomerization of AABN could be endowed to various commercial conductive meshes. Moreover, the modified meshes exhibit satisfactory removal efficiency, reusability and physical/chemical stability, which are more promising for practical applications such as fuel recycling, remote controlled oil/water separation and astronautical resource regeneration.

Lotus- and Mussel-Inspired PDA-PET/PTFE Janus Membrane: Toward Integrated Separation of Light and Heavy Oils from Water.

Current special wetting materials designed for use with oily wastewater are usually classified as either the oil-removing type or the water-removing type, which are unifunctional and limited by the oil density. Inspired by the integrated Janus system of the lotus leaf as well as the mussel-like mollusks adhered to the lotus, we fabricated a Janus polydopamine (PDA)-polyethylene terephthalate/polytetrafluoroethylene (PET/PTFE) membrane by simple immersion and tape-peeling. This membrane shows a lotuslike Janus wettability, self-cleaning effect, and floating property. Furthermore, the Janus membrane can separate light oil (ρoil < ρwater)/water mixtures with the superhydrophilic side facing upward, while heavy oil (ρoil > ρwater)/water mixtures are separated with the hydrophobic side facing upward. The separation efficiency is outstanding even after 10 repeats (>99.10%). By aid of drainage of acetone, the separation process has avoided the use of external pressure. Moreover, integrated separations of oil-in-water and water-in-oil emulsions were achieved with high efficiency. This simply prepared PDA-PET/PTFE Janus membrane has realized an integrated separation system, overcoming the monotony of traditional special wettability separation membrane and extending the bionics field into oily wastewater treatment.

Superwetting copper meshes based on self-organized robust CuO nanorods: efficient water purification for in situ oil removal and visible light photodegradation.

Water pollution has become a prominent environmental problem and insoluble oils and soluble dyes are the primary pollution sources. Herein, a facile and environment friendly method is proposed to fabricate robust CuO nanorod-covered meshes for dual-functional water purification. The as-prepared meshes can efficiently eliminate oils in wastewater and in situ photodegrade soluble organic dyes under visible light irradiation. Such a functional mesh is free-standing and recyclable, indicating the outstanding practicability of water sewage disposal. In consideration of the superiority of low-cost materials, simple method, visible-light response, ultrahigh purification efficiency and reusability, the as-prepared meshes are promising in the field of multi-functional water purification.

A versatile CeO2/Co3O4 coated mesh for food wastewater treatment: Simultaneous oil removal and UV catalysis of food additives.

Food waste water is one of the most urgent environmental problems for the close connection between food and our daily life. Herein, we use a simple hydrothermal method to prepare a highly efficient catalyst-CeO2/Co3O4 compound on the stainless steel mesh, aiming for food waste water treatment. Possessing the superhydrophilic property and catalytic ability under ultraviolet light, CeO2/Co3O4 coated mesh has successfully processed three representative contaminants in food wastewater, which are soybean oil (food oil), AR (food dye) and VA (food flavor) simultaneously with an one-step filtration. Besides, the mesh is stable in a wide pH range and performs well in reusability. Therefore, such a multifunctional material with simple preparation method, high processing efficiency and facile operation shows a promising prospect for practical production and application for food wastewater treatment.

In situ dual-functional water purification with simultaneous oil removal and visible light catalysis.

Dual purification of both oily wastewater and dye-polluted water for enhancing the use of freshwater is an urgent task. We report herein, the facile synthesis of inorganic semiconductor nanomaterials anchored mesh for in situ dual-functional water purification. This resultant mesh combines the excellent capacity of oil removal and the advantage of photocatalytic performance for dye degradation under visible light irradiation at the same time. In addition, the mesh was easily regenerated and remained unaltered in photocatalytic performance over five successive dye degradation cycles. Given the innovative integration of special wettability and photocatalytic activity of such a semiconductor material under visible light for dual elimination of various pollutants from water, we anticipate that this approach will provide a promising pathway for versatile applications in oily wastewater treatment, water purification and so on.

Polyacrylamide-Polydivinylbenzene Decorated Membrane for Sundry Ionic Stabilized Emulsions Separation via a Facile Solvothermal Method.

Aiming to solve the worldwide challenge of stabilized oil-in-water emulsion separation, a PAM-PDVB decorated nylon membrane is fabricated via a facile solvothermal route in our group. The main composition is PAM, while the PDVB plays a role as cross-linker in order to improve the interaction between the polymer and the substrate. By the combination of the superhydrophilic and underwater superoleophobic wettability of the PAM polymer with the micropore size of the substrate, the as-prepared material is able to achieve the separation of various stabilized oil-in-water emulsions including cationic type, nonionic type, and anionic type. Compared with previous works, the emulsions used in this case are more stable and can stay for several days. Besides, the solvothermal method is facile, cost saving, and relatively environmentally friendly in this experiment. Moreover, the PAM-PDVB modified membrane exhibits excellent pH stability, recyclability, and high separation efficiency (above 99%), which can be scaled up and used in the practical industrial field.