Specific Wettability Research Articles

One-Step Versatile Fabrication of Superhydrophilic Filters for the Efficient Purification of Oily Water.

As industrial oily wastewater can seriously damage ecosystems, the use of filtration technology with functional filters has emerged as an effective approach for purifying oily wastewater and protecting the environment. Although several methods for preparing functional filters with specific wettability have been reported, most methods are complicated, expensive, and time-consuming. Furthermore, these methods are only applicable to specific substrates, which hinder their practical applications. Here, a simple and versatile method for the fabrication of a superhydrophilic filter on any substrate using a one-step dipping process is reported. The method is easily scaled-up to fabricate large-area superhydrophilic filters; moreover, mass production is possible using a roll-to-roll process. The resulting filter is durable, stable, and, due to its stable hydrophilic layer, shows no deterioration in wetting behavior; it also exhibits self-cleaning properties. Based on its selective wetting characteristics, oil/water mixtures and oil-in-water emulsions stabilized by surfactants can be purified in a highly efficient manner. Importantly, owing to its self-cleaning properties, the filter can be reused after simply immersing and washing in water. This easy, cost-effective, fast, and versatile method for fabricating superhydrophilic filters can be practically applied in industries that need to purify oily water.

Dyeing performance and antibacterial properties of air-atmospheric plasma treated polyester fabric using bio-based Haematoxylum campechianum L. dye, without mordants

A hydrophobic polyester fabric with a prior surface activation using a dielectric barrier discharge (DBD) treatment was successfully dyed with natural Logwood dye (Haematoxylum campechianum L.) applying successive padding steps. Chemical and physical surface modifications were characterized by specific wettability measurements (water contact angle-WCA and % capillarity), scanning electron microscopy (SEM), zeta potential assessments and chemical quantification assay using ortho toluidine blue dye (TBO) before and after the DBD experiment. Padding processes without and with an ecofriendly formaldehyde-free acrylate binder and bioactive agent chitosan, were tested and the resulting dyeing performances were compared in terms of color strength and fastness properties. Significant color strengths were noted on the plasma activated polyester fabrics without the use of mordants. Results were highly dependent of the selected padding method used. While color intensity (K/S) depended on fixation temperature, the plasma treatment enhanced the K/S values and led to very good wash fastness (4/5). Combination of plasma treatment and acrylate binder further enhanced the fastness including rub fastness (4/5). In addition, results showed that the wet pick-up rate of dye solution was 40% higher after plasma treatment. This result was related to the new chemical and physical modification of polyester fiber surface properties after plasma treatment. Dyeing of plasma treated polyester fiber with a bio-based logwood dye without any addition of metallic mordant while imparting antibacterial properties, was found to be a promising strategy opening up a suitable eco-option for replacing some of the hazardous dyes and intermediates used in textile dyeing.

Pollens derived magnetic porous particles for adsorption of low-density lipoprotein from plasma

Adsorption of low-density lipoprotein from plasma is vital for the treatment of dyslipidemia. Appropriate adsorbent material for efficient and selective adsorption of low-density lipoprotein is highly desired. In this work, we developed pollens-derived magnetic porous particles as adsorbents for this purpose. The natural pollen grains were modified to obtain high surface porosity, a large inner cavity, magnet responsiveness, and specific wettability. The resultant particles exhibited satisfying performance in the adsorption of a series of oils and organic solvents out of water. Besides, the particles were directly utilized to the adsorption of low-density lipoprotein in plasma, which showed high selectivity, and achieved an outstanding adsorption capacity as high as 34.9% within 2 h. Moreover, their salient biocompatibility was demonstrated through simulative hemoperfusion experiments. These features, together with its abundant source and facile fabrication, makes the pollens-derived magnetic porous particles excellent candidate for low-density lipoprotein -apheresis and water treatment applications.

Adaptive Wettability of a Programmable Metasurface

Metasurfaces with specific wettability have recently been gaining relevance in numerous areas of science and industry. This hasled to the technical requirements of these functional metasurfaces increasing in cost and complexity. Examples can be found in adjustable filters and membranes, as well as in lab‐on‐chip systems. For a large number of these applications, surfaces with adaptive properties offer unique advantages compared with traditionally engineered systems. Such surfaces with adaptable surface energies, and thus wetting properties, can be realized by either a change in the surface chemistry or structure. Due to novel additive manufacturing methods such as two‐photon lithography, high‐resolution 3D microstructures can be prototypically fabricated and highly specific adjustments of the surface structure can be realized. These advances have enabled a field with particularly broad development possibilities in the area of metamaterials. Herein, a novel mechanoadaptive surface with strain‐dependent wettability states is detailed. The surface was designed, fabricated, and experimentally characterized with a custom test setup that combines the capabilities of contact angle measurements and mechanical straining in one. The results demonstrate a mechanically induced, topologically driven modification of the surface's wetting properties from the hydrophobic to the super‐hydrophobic regime.

Bioinspired Free-Standing One-Dimensional Photonic Crystals with Janus Wettability for Water Quality Monitoring.

Materials with specific wettability properties have aroused enormous interest and research for their broad application prospects in chemical reaction, medical diagnosis, biological analysis, etc. Here, inspired by the unique Janus wettability of lotus leaf and Bragg stacks of beetles, we present a free-standing film with Janus wettability and tunable structural color for water quality monitoring. This film is constructed by using a flexible polymer polyurethane (PU) to pack poly(N-isopropyl acrylamide-bis-acrylamide-acrylic acid) (P(NiPAAm-bis-AA))/TiO2 one-dimensional photonic crystals (1DPCs) into a free-standing state with Janus wettability and tunable structural color. The outer top surface of the film could achieve vivid structural color and a superhydrophobic ability; meanwhile, the outer lower surface could achieve a superhydrophilic ability. Owing to the outstanding pH-sensitive property of the P(NiPAAm-bis-AA), the Janus films could switch its structural color under different pH conditions. This imparts the free-standing film with stability and an antirotation property on the air-water interface. Based on this phenomenon, we have demonstrated a Janus wettability film, together with tunable structural color for water quality monitoring, which gives the bioinspired materials high potential applications in environmental protection.

Microfluidic Printing of Slippery Textiles for Medical Drainage around Wounds.

Surface materials with specific wettability play significant roles in existing fields from environmental protection to biomedicine. Here, a 3D droplet transport microfiber textile with slippery liquid‐infused porous surface is presented for medical drainage around wounds. The textile is fabricated by using a simple capillary microfluidic printing method to continuously spin polyurethane microfibers with liquid paraffin‐infused porous surface and print them into a 3D‐structure. Benefiting from the specific surface porous structure and oil encapsulation of the microfibers, aqueous droplets could be nondestructively and rapidly transported not only in simple single, double or multiple microfiber systems, but also in the microfibers composed stereoscopic textile through the microfluidic 3D printing. Based on this feature, it is demonstrated that the 3D slippery microfiber textile coupled with a vacuum sealing drainage therapy could significantly enhance the wound exudation drainage efficiency, reduce tissue injury, and prolong the effective service life in versatile wounds management. Thus, it is believed that the slippery microfiber textiles have potential for clinical applications.

Bioinspired superhydrophobic surface by hierarchically colloidal assembling of microparticles and colloidal nanoparticles

Functional materials with specific wettability surfaces are valuable for many areas. Extensive applications for superwettbility have led to demand for integrating devices with flexible and multi-functional. Here, inspired by the super-adhesive of mussels and the hierarchical structures of mosquitos’ compound eyes, we proposed a new method to construct functional hierarchical superhydrophobic surface by self-assembly of colloidal nanoparticles. The monolayer micron-scaled photonic crystal film is self-assembled on the surface of the liquid and deposited on the as-prepared dopamine-modified substrate. Then, a single layer of nanoscale photonic crystal film is self-assembled on the surface of the liquid and deposited on the prepared monolayer micron-scale film. In addition, the assembled structure is highly ordered and presents a certain structural color. When the surface is changed, the liquid will be injected into the ordered structure, causing the change of structure color. The hierarchical photonic crystal films with structural hydrophobic can be prepared on arbitrary intricate surfaces. Moreover, we have also explored the potential use of these hierarchical films as indicators for the surface wettability. These indicate that the hierarchical films are highly versatile for different applications.

Preparation of superhydrophobic CdS cotton using visible light response and its application for the control of water pollution

Sewage discharge produced by homes and industries contains both oil and water-soluble components. In order to remove oil from water, materials with specific wettability can be used; however, these materials cannot remove dissolved contaminants from water. In this research, we prepared a superhydrophobic CdS cotton for water purification. This material has the ability to adsorb different types of oil due to its non-wettability (WCA = 152°). Moreover, its response behavior towards visible light enables it to remove water-soluble pollutants as well. The highest oil absorption rate of superhydrophobic CdS cotton is nearly 30 times, and it can absorb light below 564 nm and produce •OH to degrade water soluble pollutants. Finally, based on Mott-Schottky curve, the position of Fermi energy level was determined (–0.55 eV). Also, the positions of valence and conduction bands were calculated based on the analysis of band gap which helps in proving photoelectric response characteristics.

Wettability and dynamics of water droplet on a snail shell

HypothesisThere are many natural surfaces with special wettabilities. Snail shells have unique rough structures, which indicates a specific wettability. In this study, the surface of a snail shell was simulated using epoxy resins, and water droplet dynamics on original and simulated snail shells were investigated to understand its special wettability. ExperimentsThe shell of the Euhadra sandai species of snails was used. The surface structure of the snail shell was simulated using epoxy resins. The surface of this EP resin was treated with UV-O3 for different periods of time. Wettabilities and dynamics of water droplet on the samples were characterized. FindingsThe surface of the snail shell with a water contact angle of approximately 85° caused the droplet to spread, which is the first report of water droplet dynamics on the shell surface. The behavior of a water droplet on the shell transformed from the Cassie state into the Wenzel state. Changes in the contact angle and diameter of the droplet base on the snail shell were larger than those on the epoxy resins. The surface roughness and chemical heterogeneity of the snail shell led to distortion of the three-phase contact line and enhancement of the spreading of the water droplet.

Recent advances of bioinspired functional materials with specific wettability: from nature and beyond nature.

Through 3.7 billion years of evolution and natural selection, plants and animals in nature have ingeniously fulfilled a broad range of fascinating functions to achieve optimized performance in responding and adapting to changes in the process of interacting with complex natural environments. It is clear that the hierarchically organized micro/nanostructures of the surfaces of living organisms decisively manage fascinating and amazing functions, regardless of the chemical components of their building blocks. This conclusion now allows us to elucidate the underlying mechanisms whereby these hierarchical structures have a great impact on the properties of the bulk material. In this review, we mainly focus on advances over the last three years in bioinspired multiscale functional materials with specific wettability. Starting from selected naturally occurring surfaces, manmade bioinspired surfaces with specific wettability are introduced, with an emphasis on the cooperation between structural characteristics and macroscopic properties, including lotus leaf-inspired superhydrophobic surfaces, fish scale-inspired superhydrophilic/underwater superoleophobic surfaces, springtail-inspired superoleophobic surfaces, and Nepenthes (pitcher plant)-inspired slippery liquid-infused porous surfaces (SLIPSs), as well as other multifunctional surfaces that combine specific wettability with mechanical properties, optical properties and the unidirectional transport of liquid droplets. Afterwards, various top-down and bottom-up fabrication techniques are presented, as well as emerging cutting-edge applications. Finally, our personal perspectives and conclusions with regard to the transfer of micro- and nanostructures to engineered materials are provided.

Recent developments of bioinspired materials with superwettability

In recent years let alone the lotus leaf structured surface, lots of other superwettable surfaces with special wettability have attracted increasingly attention, due to their unique wettability and application prospect in wide range of fields such as industrial and agricultural production; moreover, people’s daily life. Through the integration of innovations of multidimensional structure and the use of extraordinary chemistry compound, the superwettable surfaces were designed and fabricated. In this review, the superwettable phenomena in nature were concluded in detail; additional, they were specified into three categories: zero dimensional, two dimensional and three-dimensional materials. From the biomimetic perspective, several materials in the three categories that have being provided with specific wettability were fabricated, aiming at solving the remaining issues that impeding the development of superwettable surface in section of design, production and application, and the functionalities of the materials were systematically summarized. After the reviewing, the prospects of superwettable materials were discussed.

Programmable wettability on photocontrolled graphene film.

Surface materials with specific wettability play important roles in a wide variety of areas from science to industry. We present a novel paraffin-infused porous graphene film (PIPGF) with programmable wettability. Because of graphene's photothermal property, the paraffin in the PIPGF was in transition between liquid and solid in response to near-infrared (NIR) light irradiation. Thus, we imparted the film with a dynamic and reversible transition between a slippery and a rough surface as the remotely tunable wettability. In addition, with the integration of NIR masks, the paraffin could melt at corresponding patterns on the PIPGF, which formed special flow pathways for the slipping droplets. Therefore, the PIPGF could provide programmable wettability pathways for the spatiotemporal droplet manipulation by flexibly changing the NIR masks. We demonstrated these programmable wettability pathways to not only simplify liquid handling in the microplates and droplet microarrays technology but also to provide distinctly microfluidic microreactors for different purposes, such as practical blood grouping diagnosis. These features indicated that the photocontrollable PIPGF would be amenable to a variety of applications, such as microfluidic systems, laboratory-on-a-chip settings, and droplet manipulations.

Superhydrophobic Polypropylene Surfaces Prepared with TiO2 Nanoparticles Functionalized by Dendritic Polymers

ABSTRACTHybrid inorganic–organic nanomaterials have received increasing interest due to the possibility of implementing different functions and characteristics within a single material. Their functionalities are a consequence of the synergy of the properties of distinct building blocks and are related to their varied natures and spatial locations. In this work, we present the development of superhydrophobic properties on polypropylene (PP) surfaces using hybrid nanomateriales from TiO2 nanoparticles (NPs) and dendronized polymers. The dendron acryl Behera's amine was successfully grafted on the TiO2 NP surfaces by Surface‐Initiated Atom Transfer Radical Polymerization (SI‐ATRP) and a core‐brush material was obtained. Finally, PP substrates were coated with NP hybrids to produce superhydrophobic surfaces with water contact angles of over 158 degrees. Controlling the organic silane concentration on the TiO2 NPs allowed the dendronized process to be driven and thereby permitted the selection of specific wettability properties on PP substrate surfaces with high water adhesion or self‐cleaning conditions. This dendronized effect with consequent steric congestion of the polymeric brushes on the NPs changed their behaviors from Wenzel to the Cassie Baxter state. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2019–2029

Macroporous Graphene Thin Films as Electrochemical Electrodes: Enhancing the Sensitivity for Detection of Metal Ions

A macroporous graphene thin films coated on ITO substrates (MGTFs@ITO) have been developed as electrodes for the electrochemical detection of heavy metal ions. The MGTF@ITO electrodes were characterized by scanning electron microscopy, Raman spectroscopy and contact angle measurements. The results demonstrated that the MGTF@ITO has a high specific area with robust macroporous framework and a hydrophilic surface. The cyclic voltammetry and electrochemical impedance spectroscopy using MGTFs@ITO as electrochemical electrodes indicated enhanced currents at the redox peaks, enlarged electrochemical surface area and a decreased charge transfer resistance. Based on these outstanding properties, the MGTF@ITO electrodes exhibited excellent stripping performace for the analysis of Ag(I) with a detection limit of 0.005 μg L-1. The high sensitivity of the MGTF@ITO electrodes can be ascribed to the well defined macroporous framework, high electrical conductivity, high specific area and good wettability. The MGTF@ITO electrodes were further demonstrated applicable to the simultaneous determination of Zn(II), Cd(II), Pb(II), Cu(II) and Ag(I) ions with outstanding sensing performance.

Underwater Superoleophobic Wood Cross Sections for Efficient Oil/Water Separation

AbstractFunctional surfaces with specific wettability are widely encountered in nature and have inspired the development of oil‐repellent materials for oil/water separation. Despite some impressive results reported, materials combining high separation efficiency together with economical and easily scalable approaches and ideally based on renewable resources have yet to be reported. In this Communication, spruce (Picea abies) wood cross sections are proposed as oil/water separation systems. The natural wood anisotropic porous microstructure directs fluid transport, and the nature of the cell wall biopolymers results in superhydrophilicity and underwater superoleophobicity. Such wood membranes can separate water from oil with high efficiency (>99%) and high flux using only gravity and without the need for prior chemical modification of the wood scaffold. Wood also provides an intrinsic solution to scalability issues.

Superwettability integration: concepts, design and applications

Functional surfaces exhibiting superwettability offer great opportunities to develop advanced science and technology. To unite the advantages of different surfaces with special wettability, superwettability integration has been proposed and fabricated, showing a co-operative and complementary effect on material properties. This paper discusses how to combine different wettabilities and what functions can be achieved based on superwettability integration. Superwettability integration is defined as a unified system combining different superwetting materials or assembling superwetting materials with other functional materials. Four types of superwettability integrations are summarized: (a) surfaces with microscopic wettability patterns, (b) surfaces with macroscopic wettability patterns, (c) Janus interface materials with asymmetric wettability and (d) surfaces with specific wettability boundary. The functions and applications of the integrated systems are reviewed, particularly for use in fluid control, vapor condensation, fog collection and so on. The principle of designing the integration is also depicted as manipulating the significant difference in surface energy between two surfaces. On the basis of current research, some of the possible designs are finally proposed and a prospect of multifunctional superwettability integration is made.

A facile way to fabricate a superamphiphobic surface

Compared to superhydrophobic surfaces, superamphiphobic surfaces possess more potential applications but are difficult to fabricate. Herein, to address this problem, we describe a simple method to fabricate a superamphiphobic surface based on a CNTs–SiO2 hybrid material. The CNTs–SiO2 hybrid material obtained by a sol–gel approach was sprayed onto glass slides to form coatings. After surface fluorination, the sprayed coating displayed superamphiphobicity toward water and a number of organic liquids, such as dodecane. It was found that the time of fluorination slightly influenced the surface wettability of the sprayed coating. We also investigated the role of CNTs and SiO2 on superamphiphobicity establishment separately, and such information allowed us to engineer surfaces with specific wettability.

Influence of spray formulation surface tension on spray droplet adhesion and shatter on hairy leaves

An empirical spray droplet adhesion model developed to predict the adhesion of spray formulations to nonhairy leaf surfaces based on their specific wettability has previously been improved to allow predictions to hairy leaves since it had been discovered that leaf hairs cause a significant consistent increase in droplet shatter compared to nonhairy leaves (superhairy leaves demonstrate distinctly different adhesion behaviour) The current study investigated the effect of spray formulation surface tension on droplet adhesion to hairy leaf surfaces The amount of shatter on hairy leaves was found to increase with decreasing surface tension The relationship derived improved the adhesion model This enables the model to better predict the effect of spray formulation on spray droplet adhesion of hairy leaf species

Influence of Surface Properties of Carbon Fibers Biofilm Carriers on Immobilization of Different Microorganisms

Results of our workgroups have shown that carbon fibers (CFs) are high quality biofilm carriers with well biocompatibility relative to other polymer carriers used in biofilm sewage treatment. In the present study, two kinds of microorganisms, namely, aerobic nitrifier and facultative aerobic denitrifying bacterium, were immobilized on the surface of different CFs, which the effects of specific area, functional groups and wettability on immobilization of these bacteria was studied. Results show that different microorganism require for different surface properties of CFs. Biomass of immobilized aerobic nitrifier increases with increasing specific areas, surface oxygenic functional groups and wettability of CFs. It can be immobilized more facultative aerobic denitrifying bacterium if there are proper specific areas, surface functional oxygenic group and wettability on the surface of CFs

Bioinspired Colloidal Photonic Crystals with Controllable Wettability

Because of the combinatorial advantage of their unique light manipulation properties and potential applications in novel optical devices, colloidal photonic crystals (PCs), the periodic arrangement of monodispersed latex spheres, have attracted interest from researchers. In particular, colloidal PCs exhibit structural colors based on interference effects within their periodic structures. The wavelength of these colors lies in the visible range, making them particularly attractive for a variety of applications. Colloidal PCs are extensively used in templating, catalysis, and chromatographic separations. Inspired by biological PCs with both structural color and specific wettability, researchers have fabricated colloidal PCs with controllable wettability as described in this Account. The wettability can be adjusted by the intrinsic roughness of colloidal crystals in combination with the tunable chemical composition of latex surfaces. Changes in the chemical composition of the latex surface under external stimuli, such as light, electricity, and heat, can reversibly control the wettability of PCs. Furthermore, the hierarchical structure of latex particles can effectively alter the water adhesive force of superhydrophobic colloidal PCs. Patterned PCs with a variety of wettabilities can be assembled using inkjet printing from well-designed latex suspensions. By combining their structural color and specific wettability, we also exemplify some of the promising applications of colloidal PCs as templates for the construction of hierarchical structures, as indicators for controllable transport of liquid droplets, and as color-based sensors for the monitoring changes in their environment. These findings offer innovative insights into the design of novel colloidal PCs and will be of great importance for further applications of these materials.