Inspired by the water-collecting mechanism of the Stenocara beetle’s back structure, we prepared a superhydrophilic bumps–superhydrophobic/superoleophilic stainless steel mesh (SBS-SSM) filter via a facile and environmentally friendly method. Specifically, hydrophilic silica microparticles are assembled on the as-cleaned stainless steel mesh surface, followed by further spin-coating with a fluoropolymer/SiO2 nanoparticle solution. On the special surface of SBS-SSM, attributed to the steep surface energy gradient, the superhydrophilic bumps (hydrophilic silica microparticles) are able to capture emulsified water droplets and collect water from the emulsion even when their size is smaller than the pore size of the stainless steel mesh. The oil portion of the water-in-oil emulsion therefore permeates through pores of the superhydrophobic/superoleophilic mesh coating freely and gets purified. We demonstrated an oil recovery purity up to 99.95 wt % for surfactant-stabilized water-in-oil emulsions on the biomimetic SBS-SSM filter, which is superior to that of the traditional superhydrophobic/superoleophilic stainless steel mesh (S-SSM) filter lacking the superhydrophilic bump structure. Together with a facile and environmentally friendly coating strategy, this tool shows great application potential for water-in-oil emulsion separation and oil purification.Keywords: de-emulsification; stainless steel mesh; superwetting; surface energy gradient; water collection; water-in-oil emulsion separation;

•A durable underwater superoleophobic mesh was prepared by layer-by-layer assembly method.•The as-prepared mesh could be used to separate various oil/water mixtures with high efficiency.•The as-prepared mesh is durable enough to resist chemical and mechanical challenges, such as strong alkaline, salt aqueous and sand abrasion.A durable underwater superoleophobic mesh was conveniently prepared by layer-by-layer (LBL) assembly of poly (diallyldimethylammonium chloride) (PDDA) and halloysite nanotubes (HNTs) on a stainless steel mesh. The hierarchical structure and roughness of the PDDA/HNTs coating surface were controlled by adjusting the number of layer deposition cycles. When the PDDA/HNTs coating with 10 deposition cycles was decorated on the mesh with pore size of about 54 μm, the underwater superoleophobic mesh was obtained. The as-prepared underwater superoleophobic PDDA/HNTs decorated mesh exhibits outstanding oil–water separation performance with a separation efficiency of over 97% for various oil/water mixtures, which allowed water to pass through while repelled oil completely. In addition, the as-prepared decorated mesh still maintained high separation efficiency above 97% after repeated 20 separation times for hexane/water mixture or chloroform/water mixture. More importantly, the as-prepared decorated mesh is durable enough to resist chemical and mechanical challenges, such as strong alkaline, salt aqueous and sand abrasion. Therefore, the as-prepared decorated mesh has practical utility in oil–water separation due to its stable oil–water performance, remarkable chemical and mechanical durability and the facile and eco-friendly preparation process.Download high-res image (124KB)Download full-size image

•A superhydrophobic melamine sponge was fabricated by a facile photoinitiated thiol-ene click chemistry.•The resultant melamine sponge could selectively absorb and continuously remove oil from water.•The superhydrophobic melamine sponge exhibited excellent reusability.A superhydrophobic melamine sponge was fabricated by a facile method of photoinitiated thiol-ene click chemistry. The resultant sponge exhibited excellent water repellency with a water contact angle of 152.8° and could not only absorb various organic compounds with absorption capacities of 72–160 times its own weight, but also selectively and continuously remove oil from water. More importantly, the sponge still maintained a high absorption capacity after reused 16 times by sorption/squeezing. Additionally, the superhydrophobic sponge could also be used as a filter to separate oil/water mixtures successfully. These results suggest that the resultant superhydrophobic melamine sponge may provide great potential application for oil removal.

•A crosslinkable POSS-containing fluorinated copolymer was synthesized via a free radical copolymerization.•A superhydrophobic/superoleophilic cotton fabric was fabricated using the copolymer and the coated cotton fabrics possess robust superhydrophobic performance.•The coated cotton fabrics could separate various oil-water mixtures with high efficiency and exhibit durable separation capability.A superhydrophobic/superoleophilic cotton fabric was fabricated by a facile one-step dip-coating method using a crosslinkable fluorinated copolymer material-Poly(methyl methacrylate-co-butyl acrylate-co-hydroxyethyl methacrylate-co-perfluoroalkylethyl methacrylate-co-stearyl methacrylate-co-methacrylisobutyl polyhedral oligomeric silsesquioxane) (P(MMA-BA-HEMA-FMA-SMA-MAPOSS)). The copolymer was synthesized using a conventional solution free radical polymerization. Cotton fabric was dip-coated in tetrahydrofuran (THF) solution of the copolymer and curing agent with –NCO groups. The coated cotton fabric has a water contact angle above 150° and oil contact angle of 0°, showing both superhydrophobicity and superoleophilicity. Furthermore, the cotton fabric could keep its superhydrophobic property even after ultrasonic treatment in ethanol or thermal treatment, as well as for acidic or alkaline liquids. The coated cotton fabrics were used to separate various oil-water mixtures with separation efficiency all above 96%. Additionally, the cotton fabrics still kept high separation efficiency above 98% after 50 separation times for n-hexane/water mixture. These suggest that the coated cotton fabric possesses robust superhydrophobic property and excellent oil-water separation performance, and can finely meet the urgent request in oil-water separation.

•A novel superhydrophilic-underwater superoleophobic Cu2S coated copper mesh was prepared via an anodization approach.•The coated mesh could be used to separate various oil-water mixtures with high efficiency.•The mesh maintained separation efficiency above 97% after repeated 50 separation times for hexane/water mixture.A novel Cu2S coated copper mesh with unique curled plate-like structure was prepared via a simple and cost-effective electrochemical anodization approach. The as-prepared coated mesh shows superhydrophilicity and underwater superoleophobicity and low adhesion property to oil. The mesh was used to separate various oil-water mixtures with high efficiency, which allowed water to pass through while it repelled oil completely. In addition, the coated mesh still maintained high separation efficiency above 97% after repeated 50 separation times for hexane/water mixture. These suggest that the coated mesh possesses superhydrophilic and underwater superoleophobic properties and stable oil-water separation performance. Therefore, the Cu2S coated copper mesh can be a novel ideal candidate material for oil-water separation.

Dissipative particle dynamics (DPD) simulation was used to investigate the self-assembling dynamics process of poly(styrene-b-ethylene oxide) (PS-b-PEO) block copolymer and quantum dots (QDs) in an aqueous solution. The effects of molecular weight (MW) and segment construction of a PS–PEO block copolymer on the structure and size of the self-assembled micelles were discussed. The structural properties of micelles were characterized by a radial distribution function. The simulation results are qualitatively consistent with those of previous experiments and show that there are only small QD clusters. The hydrophobic PS chains form the micelle core, while the hydrophilic PEO chains form the shell. The size of the self-assembled PS–PEO/QDs micelle increases with the MW of PS-b-PEO block copolymer and the lengths of PEO and PS segments. The simulation results indicate that the assembling process includes four sequential transient stages: (1) the random distribution of all components in aqueous solution; (2) formation of small clusters with polymer chains and QDs; (3) crashing together of small spheres and the formation of larger aggregates; (4) stabilization of assembled micelles. The simulation reveals the physical insights of the QD loading mechanism of the PEG micelle at the mesoscopic scale, indicating the DPD simulation can be used as an adjunct to provide other valuable information for experiments.

Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.

An epoxy resin was used to prepare crosslinked polyurethane hybrid emulsion through the blocked NCO prepolymer mixing process. Due to their hydrophobicity, the amine chain extender, blocked –NCO, and epoxy are located inside the emulsion particles. Thus, the crosslinking reaction occurs mostly in the interior of the particles. In this way, the crosslinking density of the resin is increased without the use of solidifying agents or heating during film formation, and the stability of the emulsions remains uninfluenced. The effects of the type of amine chain extender and the type, dosage, and addition mode of the epoxy resin were studied in terms of mechanical properties and swelling properties in water and toluene of the cast films. Additionally, the stability of the single-pack hybrid emulsion was studied. The results showed that the sample prepared with diethylene triamine had good stability, chemical resistance, and high mechanical strength. The modulus and water resistance of the films increased with the epoxy resin content, which could reach 20 wt%. The type of amine chain extender affected the stability of the emulsions significantly. The molar ratio of NH/NCO at 1:1 led to the best film performance. The optimal temperature of the chain-extension reaction was approximately 80°C. The hybrid emulsions could be stored for at least 6 months without apparent performance changes.

Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.