The counterions of polydiallyldimethylammonium (PDADMA) coatings were altered by incubation in aqueous solutions of different electrolytes. Oil de-wetting on the resulting polycationic surfaces upon water action exhibited a straightforward connection with the Jones–Dole viscosity B-coefficient (Bη) sign of surface counteranions. Upon water action, surface counteranions with negative Bη render PDADMA coatings oil-adhering, but those with positive Bη furnish PDADMA coatings with excellent self-cleaning. The oil-adhering PDADMA surfaces can become self-cleaning upon water action in response to the Bη of surface counteranions sign-switching with increasing water temperature. Courtesy of surface counter-anions with Bη>0, self-cleaning PDADMA coatings enable not only conversion of conventional meshes into self-cleaning membranes for oil/water separation, but also regioselective maneuver of oil flow on polycationic surfaces according to the Bη sign of surface counteranions patterned atop. 相似文献
Coating solid surfaces with cellulose nanofibril (CNF) monolayers via physical deposition was found to keep the surfaces free of a variety of oils, ranging from viscous engine oil to polar n ‐butanol, upon water action. The self‐cleaning function was well correlated with the unique molecular structure of the CNF, in which abundant surface carboxyl and hydroxy groups are uniformly, densely, and symmetrically arranged to form a polar corona on a crystalline nanocellulose strand. This isotropic core–corona configuration offers new and easily adoptable guidance to design self‐cleaning surfaces at the molecular level. Thanks to its excellent self‐cleaning behavior, the CNF coating converted conventional meshes into highly effective membranes for oil–water separation with no prior surface treatment required. 相似文献
Due to their high surface energy, hydrophilic surfaces are susceptible to contaminations which are difficult to remove and often ruin the surface. Traditional anti‐fog coatings are especially limited by contaminants, as the prevention of fogging is enhanced as hydrophilicity increases. Thus, advanced solutions to fogging are required which incorporate some degree of self‐cleaning ability without significant losses in anti‐fog character. Potential next generation anti‐fog surfaces are characterized with particular emphasis on extended lifetime stimuli‐responsive surfaces. Surfactant‐based surfaces exhibited simultaneous hydrophilicity, necessary for anti‐fogging, and oleophobicity, necessary for contamination resistance. The combination of these features rendered the surface as self‐cleaning.
The various morphology and structure microspheres were fabricated via one‐step single‐solvent electrospraying of hydrophilic and hydrophobic block modified copolymer of polycaprolactone (PCL). A honeycomb‐like hierarchical structure microspheres of PCL‐b‐PTFOA(4h) and abundant nanometer pores of PCL‐b‐PEG400 microspheres were obtained due to the solvent evaporation, thermally and polymer diffusion‐induced phase separation effect. Furthermore, a superhydrophobic coatings and robust superhydrophobic‐coated cotton woven fabric surfaces were prepared by using PCL‐b‐PTFOA(4h) microspheres with hierarchical structure and low surface energy. The contact angle (CA) and sliding angle (SA) of PCL‐b‐PTFOA(4h) microspheres‐coated cotton woven fabric surfaces reached 164.4 ± 5.5° and 6.8 ± 0.5°, respectively, which allows for self‐cleaning. The self‐cleaning test demonstrated that the coated superhydrophobic surface could shed aqueous dyes and dust without any trace. The superhydrophobic‐coated fabric shows good soaping fastness against mechanical abrasion without significant reduction of CA. This electrospraying coating of block copolymers can provide a simple, facile, and promising technique for producing multifunctional textiles. 相似文献
Membranes with special functionalities, such as self‐cleaning, especially those for oil/water separation, have attracted much attention due to their wide applications. However, they are difficult to recycle and reuse after being damaged. Herein, we put forward a new N‐substituted polyurethane membrane concept with self‐healing ability to address this challenge. The membrane obtained by electrospinning has a self‐cleaning surface with an excellent self‐healing ability. Importantly, by tuning the membrane composition, the membrane exhibits different wettability for effective separation of oil/water mixtures and water‐in‐oil emulsions, whilst still displaying a self‐healing ability and durability against damage. To the best of our knowledge, this is the first report to demonstrate a self‐healing membrane for oil/water separation, which provides the fundamental research for the development of advanced oil/water separation materials. 相似文献
While of immense scientific interest, superhydrophilic surfaces are usually difficult to prepare, and preparation methods are typically substrate specific. Herein, a one‐step coating method is described that can endow superhydrophilicity to a variety of substrates, both inorganic and organic, using the coordination complexes of natural phytic acid and FeIII ions. Coating deposition occurs in minutes, and coatings are ultrathin, colorless, and transparent. Superhydrophilicity is attributed, in part, to the high density of phosphonic acid groups. The ease, rapidness, and mildness of the assembly process, which is also cost‐effective and environmental‐friendly, points towards potential applications, such as self‐cleaning, oil/water separation, antifogging. 相似文献
The interest in highly water‐repellent surfaces has grown in recent years due to the desire for self‐cleaning surfaces. A super‐hydrophobic surface is one that achieves a water contact angle of 150° or greater. This article explores the different approaches used to construct super‐hydrophobic surfaces and identifies the key properties of each surface that contribute to its hydrophobicity. The models used to describe surface interaction with water are considered, with attention directed to the methods of contact angle analysis. A summary describing the different routes to hydrophobicity is also given. 相似文献
Superhydrophobic and superhydrophilic surfaces are of great interest because of a large range of applications, for example, as antifogging and self‐cleaning coatings, as antibiofouling paints for boats, in metal refining, and for water–oil separation. An aqueous ink based on three‐dimensional graphene monoliths (Gr) can be used for constructing both superhydrophobic and superhydrophilic surfaces on arbitrary substrates with different surficial structures from the meso‐ to the macroscale. The surface wettability of a Gr‐coated surface mainly depends on which additional layers (air for a superhydrophobic surface and water for a superhydrophilic surface) are adsorbed on the surface of the graphene sheets. Switching a Gr‐coated surface between being superhydrophobic and superhydrophilic can thus be easily achieved by drying and prewetting with ethanol. The Gr‐based superhydrophobic membranes or films should have great potential as efficient separators for fast and gravity‐driven oil–water separation. 相似文献
Summary: Rough polydimethylsiloxane (PDMS) surface containing micro‐, submicro‐ and nano‐composite structures was fabricated using a facile one‐step laser etching method. Such surface shows a super‐hydrophobic character with contact angle higher than 160° and sliding angle lower than 5°, i.e. self‐cleaning effect like lotus leaf. The wettabilities of the rough PDMS surfaces can be tunable by simply controlling the size of etched microstructures. The adhesive force between etched PDMS surface and water droplet is evaluated, and the structure effect is deduced by comparing it with those own a single nano‐ or micro‐scale structures. This super‐hydrophobic PDMS surface can be widely applied to many areas such as liquid transportation without loss, and micro‐pump (creating pushing‐force) needless micro‐fluidic devices.
Etched PDMS surface containing micro‐, submicro‐, and nano‐composite structures shows a self‐cleaning effect with water CA as high as 162° and SA lower than 5°. 相似文献
The adsorption behavior of 2H‐tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (2HTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces have been investigated by using variable‐temperature scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. On the bare Cu(110) surface, individual 2HTTBPP molecules are observed. These molecules are immobilized on the surface with a particular orientation with respect to the crystallographic directions of the Cu(110) surface and do not form supramolecular aggregates up to full monolayer coverage. In contrast, a chiral supramolecular structure is formed on the Cu(110)–(2×1)O surface, which is stabilized by van der Waals interactions between the tert‐butyl groups of neighboring molecules. These findings are explained by weakened molecule–substrate interactions on the Cu(110)–(2×1)O surface relative to the bare Cu(110) surface. By comparison with the corresponding results of Cu–tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin (CuTTBPP) on Cu(110) and Cu(110)–(2×1)O surfaces, we find that the 2HTTBPP molecules can self‐metalate on both surfaces with copper atoms from the substrate at room temperature (RT). The possible origins of the self‐metalation reaction at RT are discussed. Finally, peculiar irreversible temperature‐dependent switching of the intramolecular conformations of the investigated molecules on the Cu(110) surface was observed and interpreted. 相似文献
Nowadays, introducing self‐cleaning properties on various fabrics under daylight irradiation for automotive and upholstery application is in a central point of research. This can be achieved by application of metal‐doped TiO2 nano particles on the textile fabrics. Here, alkali hydrolysis of polyester fabric has been carried out along with synthesis of Cu2O/TiO2 nanoparticles in a single‐step process by using sonochemical technique. CuSO4.5H2O was used as a source of copper in the presence of glucose as reducing and stabilizing agent. Moreover, central composite design based on response surface methodology (RSM) was used to determine the role of variables (CuSO4.5H2O, glucose and pH) and their effects on the self‐cleaning properties and weight of the fabric. The self‐cleaning property was investigated by degradation of Methylene blue on the surface of the treated fabrics under daylight. Further, the tensile properties, colorimetric measurement, and washing fastness of the treated fabric produced in the optimum conditions were investigated. The morphology of Cu2O/TiO2 nanoparticles was examined using X‐ray diffraction and field emission scanning electron microscopy (FESEM). The new polyester fabric obtained through in situ synthesis of Cu2O/TiO2 nanoparticles can be used as a desirable stable fabric with high tensile strength and visible‐light self‐cleaning properties. 相似文献
Globally, efficient oil‐water separation for surfactant‐stabilized oil‐water emulsions has been in urgent demand. The current options available for separation are neither sustainable nor resistant to fouling. Herein, we introduce a hierarchically nanostructured TiO2/Fe2O3 composite membrane, which is capable of separating surfactant‐stabilized oil‐water emulsions with high separation efficiency. The high oil rejection rate is contributed by the acquisition of an interconnected delicate network and underwater superoleophobic interface. Meanwhile, its self‐cleaning function promote the facile recovery of the contaminated membrane. Furthermore, the mechanical flexible characteristic of the TiO2/Fe2O3 composite membrane widens its applicability in industrial employment. Thanks to these properties, this novel membrane can be considered as a practical option for treating surfactant‐stabilized oil‐water emulsions. 相似文献