•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 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

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 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.

An ambient-temperature self-crosslinkable acrylic resin was synthesized by solution polymerization, with ethanol as solvent; butyl acrylate (BA), methyl methacrylate (MMA), acrylic acid (AA), hydroxypropyl acrylate (HPA), and diacetone acrylamide (DAAM) as monomers; and adipic acid dihydrazide (ADH) as crosslinker. The resin could be diluted by water. The resin was used for PE film ink, and its curing behavior and film properties were studied. FTIR and DSC results indicated that the reaction between ketone carbonyl and hydrazine groups could occur during film curing at ambient temperature and improved glass transition temperature (Tg) of the film by 12.67°C. Crosslinking density of film increased with DAAM content and m(ADH)/m(DAAM) ratio. Adhesion on PE film increased with DAAM content, while it first increased then decreased with m(ADH)/m(DAAM) ratio. Water absorption of film decreased with DAAM content, while it first decreased then increased with m(ADH)/m(DAAM) ratio. The optimal m(ADH)/m(DAAM) ratio and DAAM content in this experiment are 0.8:1 and 2%, respectively. Compared with ambient-temperature self-crosslinkable emulsion, this water-soluble resin shows film not only with the same adhesion, but also without any shrinkage void, indicating better film-forming ability on PE film. The ambient-temperature self-crosslinkable water-soluble acrylic resin shows excellent potential application in water-based ink for PE film because of good film-forming ability and adhesion and low water absorption.

•A low-temperature self-crosslinkable acrylate emulsion was synthesized.•The effect of ketone-hydrazide crosslinking reaction on polymer film was discussed.•The adhesion ratio, crosslinking density and water absorption ratio tests were performed.•The emulsion has good potential application in water-based ink for PE thin film.A low-temperature self-crosslinkable acrylic emulsion was synthesized by semi-continuous emulsion polymerization technology using methyl methacrylate (MMA), butyl acrylate (BA), acrylic acid (AA) and diacetone acrylamide (DAAM) as monomers and adipic dihydrazide (ADH) as crosslinker. Transmission electron microscope (TEM) micrograph disclosed spherical emulsion particles possess core–shell structure. Fourier transform infrared (FTIR) spectrogram showed that crosslinking reaction between CO groups of DAAM and NHNH2 groups of ADH can occur during coating film formation at low temperature, even at room temperature. Differential scanning calorimeter (DSC) analysis indicated that glass transition temperature (Tg) of the crosslinked film is increased by 5 °C. Thermogravimetric analysis (TGA) curves demonstrated that self-crosslinking reaction improves thermal stability of film. As DAAM content increased from 0% to 2%, water absorption ratio of film decreased from 26.2% to 7.4%, adhesion ratio on the PE thin film increased from 0% to 97%. While the n(ADH)/n(DAAM) ratio increased from 0:1 to 0.8:1, crosslinking density of films was increased from 0% to 88%, water absorption ratio decreased from 36.5% to 7.4% and adhesion ratio on the PE thin film increased from 0% to 97%. The optimal DAAM content and n(ADH)/n(DAAM) ratio was 2% and 0.8:1 in this experiment. The emulsion has good potential application in water-based ink for PE film.

Polyester-PEG dendrimers are attractive for in vivo delivery of anti-cancer drug because of their biodegradability and low cytotoxicity. In this drug delivery system, G5-PEG polyester dendrimer is composed of hydrophobic polyester dendritic blocks and hydrophilic poly (ethylene glycol) (PEG), in which DOX molecules are efficiently encapsulated in the core of microspheres due to their affinity with G5 dendritic blocks. A dissipative particle dynamics (DPD) computational method was used to investigate the loading/release mechanism of anti-cancer drug doxorubicin (DOX) in G5-PEG polyester dendrimer. Four sequential transient stages were found during the drug encapsulation process: (1) all components distribute randomly in the cubic box at the initial stage, (2) DOX molecules dispersion in the G5-PEG dendritic microsphere, (3) amalgamation of the small core–shell dendritic microspheres into bigger ones, and (4) the stabilization stage. The loaded DOX content was calculated to be 16.7 % with a loading efficiency of 100 %, which is close to the experiment results (15.2 % DOX content with the loading efficiency of 99 %). The simulation also successfully revealed the drug release dynamics at pH 7.4 and pH 5 (37 °C). At pH 7.4, no DOX molecule was released from G5-PEG/DOX when only considered the influence of temperature on drug release. It demonstrates that the increase of system temperature (from 25 to 37 °C) is not the major factor for drug release at pH 7.4. When considered protonation of DOX at pH 5, it is benefit to generate some pores on the surface of G5-PEG/DOX microspheres, and the aperture of the pores increased with the simulation steps increased, which leads to the increasingly exposure of DOX molecules to water. However, the drug could not release toward the aqueous solution. It demonstrated that the protonation of DOX is not the major factor for the drug’s rapid release at pH 5 though it may facilitate the drug release process. Such results are in qualitatively consistent with the experimental observations and could provide valuable guidance in later design and optimization of this drug delivery system. The same tool could also be used to evaluate and design other similar drug/gene delivery systems.