Hydrophobic Silica Research Articles

Two-stage thiol-ene click reaction for fluorine-free superhydrophobic fabrics with buoyancy boost and drag reduction

Superhydrophobic fabrics suggest tremendous potential in some emerging fields such as electronic skin, bioelectronic sensors and special clothing due to their excellent liquid repellency and self-cleaning properties. However, currently reported superhydrophobic materials are usually prepared using biologically toxic fluorinated compounds, which severely restricts their practical applications. Herein, we propose a two-step thiol-ene click reaction strategy to fabricate fluorine-free superhydrophobic cotton fibers (Fabric-SH-PB-SiO2). The 1,2-polybutadiene (1,2-PB) with flexible rubber molecular chains and low surface energy was coated by cotton fiber through thiol-ene click reaction. Subsequently, based on this reaction, the coated cotton fiber was used to establish chemical bonds with hydrophobic silica. The Fabric-SH-PB-SiO2 possesses a rich multi-level micro-nano structure that can form stable air layer on the surface of the fabric, which showed a high hydrophobic angle of 156° and exhibited some distinct advantages such as anti-fouling and self-cleaning characteristics, high buoyancy, and reduced drag. More remarkably, the Fabric-SH-PB-SiO2 could float on the water surface after carrying 34 times its weight. Compared with unmodified fabrics, the Fabric-SH-PB-SiO2 demonstrated a high drag reduction rate of up to 102 %, among the highest values for the reported hydrophobic materials. The strategy developed here provides insights towards fabricating high-buoyancy fluorine-free superhydrophobic cotton fibers.

Development of self-cleaning superhydrophobic cotton fabric through silica/PDMS composite coating

The lotus effect informs that self-cleaning superhydrophobic surfaces can be obtained by creating rough surface structures and modifying them with chemicals that have low surface energy. Herein, the composite of hydrophobic silica nanoparticles (SNPs) and polydimethylsiloxane (PDMS) was deposited on cotton fabric by multiple dip cycles. At optimal condition, the agglomerated SNPs in PDMS produces a hierarchical rough surface, as a result the coated cotton fabric has revealed a water contact angle (WCA) of 158.41 ± 1.58° and 4° of sliding angle. Due to negligible water adhesion to a superhydrophobic surface, coated cotton fabric reveals excellent self-cleaning behavior, which was tested by dust particles, muddy water and tea droplets. Furthermore, coated cotton fabric sustains superhydrophobicity over the mechanical robustness tests including adhesive tape peeling test, sandpaper abrasion test, and ultrasonication. Therefore, such an approach may be applicable in textile industries for self-cleaning purposes.

A facile two-step method to construct environmental-friendly Janus coconut wood membrane for oil/water separation

The Janus structure and the super hydrophilicity of cellulose inspired to develop of low-cost and environmentally friendly Janus membrane materials with opposite wetting behavior for unidirectional water/oil transport and selective water/oil separation. However, it remains a challenge to prepare pollution-free, fluoride-free, low-cost Janus membranes in a simple way. A facile two-step top-down approach is utilized to prepare the Janus coconut wood (JCW) membrane using natural coconut wood in the transverse direction as raw material. The lignin and hemicellulose were removed from the coconut wood to prepare super-hydrophilic coconut wood (SCW). The SCW was then sprayed with hydrophobic silica gel to form a super-hydrophobic surface on one side which the water contact angle reached 153.4°. It was observed that the Janus membrane maintained chemical stability in highly saline and varied pH conditions, as well as at a long friction distance. Meanwhile, Janus coconut wood membrane oil/water separation devices readily achieve on-demand unidirectional oil/water transportation due to their superior separation efficiency of over 98 % and separation flux of over 4125 L/m2·h. The Janus coconut wood membrane provides a practical and effective solution for separating the oil/water mixture.

Interplay between Shelf Life and Printability of Silica-Filled Suspensions.

Although fumed silica/siloxane suspensions are commonly employed in additive manufacturing technology, the interplay between shelf life, storage conditions, and printability has yet to be explored. In this work, direct ink writing (DIW) was used to print unique three-dimensional structures that required suspensions to retain shape and form while being printed onto a substrate. Suspensions containing varying concentrations of hydrophobic and hydrophilic silica were formulated and evaluated over a time span of thirty days. Storage conditions included low (8%) and high (50%) relative humidity and temperatures ranging from 4 °C to 25 °C. The shelf life of the suspensions was examined by comparing the print quality of pristine and aged samples via rheology, optical microscopy, and mechanical testing. Results showed a significant decrease in printability over time for suspensions containing hydrophilic fumed silica, whereas the printability of suspensions containing hydrophobic fumed silica remained largely unchanged after storage. The findings in this work established the following recommendations for extending the shelf life and printability of suspensions commonly used in DIW technology: (1) higher fumed silica concentrations, (2) low humidity and low temperature storage environments, and (3) the use of hydrophobic fumed silica instead of hydrophilic fumed silica.

Direct Write Printing of Ultraviolet-Curable Bulk Superhydrophobic Ink Material.

Although superhydrophobic surfaces have various promising applications, their fabrication methods are often limited to 2D plane surfaces that are vulnerable to abrasion and have limited adhesion to the substrate. Herein, an ultraviolet (UV) curable ink with bulk superhydrophobicity, consisting of poly(dimethylsiloxane) (PDMS) resins, hydrophobic silica, and solvent (porogen), was successfully developed for UV-assisted direct write printing processing. After UV curing of the ink followed by solvent evaporation, the generated porous structure cooperates with silica particles to form a self-similar and hierarchical structure throughout the bulk material, which can keep its original morphology even after cyclic abrasion (over 1000 times) and thus exhibits durable superhydrophobicity. With this unique ink, UV-assisted direct write printing can not only create 2D superhydrophobic surfaces on various substrates (e.g., paper and wire mesh) but also fabricate self-supporting 3D superhydrophobic objects for various applications such as waterproofing and oil-water separation. The printed objects exhibited a stable superhydrophobicity against liquid corrosion and mechanical damage. In addition, the 3D printing approach can be used to optimize the oil-water separation performance of the superhydrophobic porous materials by tuning the pore size, thus presenting promising applications.

Puncture Resistance and UV aging of Nanoparticle-Loaded Waterborne Polyurethane-Coated Polyester Textiles.

The goal of this research was to investigate the effect of different types of nanoparticles on the UV weathering resistance of polyurethane (PU) treatment in polyester-based fabrics. In this regard, zinc oxide nanoparticles (ZnO), hydrophilic silica nanoparticles (SiO2 (200)), hydrophobic silica nanoparticles (SiO2 (R812)), and carbon nanotubes (CNT) were mixed into a waterborne polyurethane dispersion and impregnated into textile samples. The puncturing resistance of the developed specimens was examined before and after UV-accelerated aging. The changes in chemical structure and surface appearance in nanoparticle-containing systems and after UV treatments were documented using microscopic pictures and infrared spectroscopy (in attenuated total reflectance mode). Polyurethane impregnation significantly enhanced the puncturing strength of the neat fabric and reduced the textile's ability to be deformed. However, after UV aging, mechanical performance was reduced both in the neat and PU-impregnated specimens. After UV treatment, the average puncture strength of all nanoparticle-containing systems was always greater than that of aged fabrics impregnated with PU alone. In all cases, infrared spectroscopy revealed some slight differences in the absorbance intensity of characteristic peaks for polyurethane polymer in specimens before and after UV rays, which could be related to probable degradation effects.

Fabrication and characterization of hydrophobic/hydrophilic dual-layer polyphenyl sulfone Janus membrane for application in direct contact membrane distillation

In this study, single-layer (SL) and dual-layer (DL) polyphenyl sulfone (PPSU) flat sheet nanocomposite Janus membranes were fabricated via a combination of VIPS and NIPS techniques for direct contact membrane distillation (DCMD) for the first time. Hydrophobic silica nanoparticles (SiNP-B) were incorporated into the SL membranes and the top layer of the DL membranes, while hydrophilic silica nanoparticles (SiNP-L) were added into the down layer of the DL membranes. The effect of the SiNP-B concentration (1–5 wt%) and the top layer thickness (50 and 100 μm) on the morphology, mean pore size (MPS), thickness, porosity, surface roughness, water contact angle (WCA), liquid entry pressure, mechanical strength, and thermal conductivity were investigated. All of the membranes showed a finger-like structure surrounded by a sponge-like structure. The membranes were examined in the DCMD of a 35,000 ppm saline solution at different feed temperatures (50–70 °C) and flow rates (250–1000 mL/min). The DL membranes possessed higher fluxes than the SL membranes through increasing MPS and WCA. The DL membrane with a SiNP-B concentration of 2 wt% and a hydrophobic thickness of 50 μm (DL- 2,50) achieved the highest flux (42.68 ± 0.35 kg/m2h) and salt rejection (94.90 %) during 5 h. This membrane has an MPS of 0.22 ± 0.03 μm, a thickness of 201 ± 4 μm, and a porosity of 76 ± 2 %. It could be concluded the proper pore size distribution is the most important factor in achieving a successful DCMD operation.

Effects of different grain size of expanded perlite aggregate and content of silica aerogel on the characteristics of lightweight cementitious composite

In this research, an attempt was made to investigate effects of expanded perlite aggregate grain size on consistency, density, compressive strength, thermal conductivity and microstructure of 15 different composite mixes with silica aerogel. As for the samples preparation, expanded perlite aggregate of 5 different groups based on grain size, were used for sample preparation, then partially replaced by volume for 20% and 40% of hydrophobic silica aerogel particles. The results showed, that density of the samples varied between 0.35 g/cm3 and 1.5 g/cm3, flexural strength varied between 3.4 MPa and 7.4 MPa, compressive strength was in the range between 12.3 MPa and 55 MPa, thermal conductivity coefficient was in the range between 0.130 W/mK and 0.190 W/mK. Scanning electron microscopy showed that expanded perlite aggregates and silica aerogel particles are capable of being mixed and formed homogenous mixture. Nevertheless, microscope images indicated weaker adhesion of silica aerogel particles at interfacial zone as compared with expanded perlite aggregate particles. Results revealed, that both of the factors: grain size of expanded perlite aggregate particles silica aerogel content influenced the density, compressive strength and thermal conductivity. The study also indicated feasibility of expanded perlite aggregate and silica aerogel for achieving homogeneous mixture of the lightweight cementitious composites. Study demonstrated that using different size fractions of expanded perlite aggregate affects differently physical, mechanical and thermal characteristics of the lightweight cementitious composite with silica aerogel.

Synergistic effects of silica aerogels and SDS nanofluids on CO2 sequestration and enhanced oil recovery

This study explores the combined application of hydrophobic silica aerogels and SDS to enhance CO2 storage capacity and oil recovery. Experimental data highlighted a marked increase in CO2 solubility within silica aerogel-SDS nanofluids compared to brine and SDS solutions. Molecular dynamics simulations revealed CO2 adsorption into nanopores. Silica aerogel nanoparticles extended CO2 foam half-life by 6 % versus 62 % decline for sole SDS foam from 30 to 140 °C. Adjusting the SDS to nanoparticle ratio affects foam properties, with a ratio of 1.5 yielding optimal results. Core flooding experiments demonstrated a 75 % rise in CO2 trapping efficiency using the nanofluids over SDS solutions. Two-dimensional tests showed aerogel-SDS foam surpassed SDS foam flooding by 12 % incremental oil recovery in upper layers, attributed to enhanced profile control. The combined agents present an effective approach for geological CO2 storage and EOR optimization.

A silica aerogel-based thermal insulation composite film for metal surfaces in gas industries

Silica aerogels are ultralight superinsulators that can increase the efficiency of insulation materials up to three times. In this study, hydrophobic silica aerogels were synthesized using an inexpensive and available water-glass precursor at ambient pressure, without the need for specific equipment using the sol-gel method. The formation of silica aerogels was confirmed using FT-IR, SEM, TEM, BET and BJH methods. Thermal stability and hydrophilicity of silica aerogels were investigated by TGA and contact angle measurement, respectively. Then, composites including an equal amount of anti-corrosion of alkyd resin-zinc Chromate containing weight percentages 0, 1, 5, 10, 20, 30, 40 and 50 were prepared from silica aerogels. The thermal conductivity of the composites was measured in a liquid state. The results indicated a significant decrease in the thermal conductivity by increasing the weight percentage of silica aerogel. The composite adherence was then evaluated. Composites with the highest amount of aerogel with proper adherence according to the standard set by the National Gas Company of Isfahan province, along with paint thinner for dilution and colorless cobalt drier, were coated on aluminum plates of thickness of 1.2 mm and the thermal conductivity of the film was measured in dry state. The results of this study showed that the composite containing 30% by weight of silica aerogel and B5 adherence had the least thermal conductivity and it can be used as a thermal insulation of various equipment in the gas industries.

In Ukrainian

Efficient and environmentally friendly means for fire extinguishing can reduce extreme economic losses from fires and protect people's lives and property. A separate problem is extinguishing oil products on the water surface. Dry water is a new type of environmentally friendly fire extinguishing agent. It is a powder with a water content of more than 90 %, so it has excellent fire extinguishing properties. The purpose of this work was to obtain dry water fire extinguishing powders based on pyrogenic hydrophobic methyl silica with bentonite and to study their fire extinguishing properties in case of extinguishing gasoline on water surface. To obtain dry water fire extinguishing powders, there were used distilled water, Dashukovsky bentonite (Ukraine), and pyrogenic methyl silica (AM-300 brand, Ssp = 300 m2/g, particle size 5–7 nm) (Kalush, Ukraine). Dry water fire extinguishing powder was prepared by mixing the components at a speed of 15000 rpm for 10 s. Were made samples containing 10 wt. % methyl silica, 3, 6, 10, and 15 wt. % bentonite and the corresponding amount of water. The bulk density was 0.423, 0.453, 0.459, and 0.464 g/cm3 for samples of 3, 6, 10, and 15 wt. % bentonite, respectively. Optical microscopy has shown that the particles of the dry water powder have a clearly visible core-shell structure. Dry water fire extinguishing powder is a polydisperse system - most of the particles are single fine particles with a size of 1 micron or less, and there are also agglomerates with a size of more than 5 microns. As a result of the mechanical destruction of individual bentonite particles during high-speed mixing of components, bentonite particles are destroyed, therefore, individual bentonite particles are surrounded by a hydrophobic-hydrophilic mixture of hydrophobic silica nanoparticles and bentonite nanoparticles formed during exfoliation. The study of the fire-extinguishing properties of the dry water powder was carried out by spraying it onto a layer of burning gasoline A92 on water surface. The time to complete extinguishing of the fire and the consumption of the substance per unit area of burning were determined. It has been determined that the time for extinguishing gasoline and the consumption of dry water fire extinguishing powder for extinguishing it depend on the concentration of bentonite and are for 3, 6, 10, and 15 wt. % 9, 7, 6, and 9 s and 0.333, 0.309, 0.284, and 0.260 g/cm3, respectively. The developed dry water fire extinguishing powders are environmentally friendly, have good fire extinguishing properties, and can be used to extinguish oil products on the surface of water bodies.

Development of a novel hierarchical porous and hydrophobic silica from montmorillonite for benzene adsorption

A hierarchical porous and hydrophobic adsorbent is the key to removing the volatile organic compounds through adsorption technology, especially under humidity conditions. In this work, we synthesized a hierarchical porous and hydrophobic montmorillonite-derived adsorbent by a facile strategy, i.e., a combination of ball milling, acid activation, and thermal treatment. Our results showed that ball milling could efficiently grind the montmorillonite sheets into small fragments, which caused the rapid dissolution of octahedral cations from the edges of these fragments during the subsequent acid activation process. The resulting porous silica showed more porosity (including micropores and mesopores) and a larger specific surface area (664 m2 g−1), compared with the product (345 m2 g−1) obtained by only acid washing without ball milling. The next thermal treatment readily removed the surface hydroxyl of porous silica, leading to the formation of the target product (HP-SiO2) with enhanced hydrophobicity and well-preserved pore structures. As an adsorbent for benzene molecules, HP-SiO2 exhibited a high dynamic benzene adsorption capacity (257.1 mg g−1) due to the large specific surface area and abundant micropores. Furthermore, HP-SiO2 maintained outstanding benzene adsorption performance under different humidity conditions (with a high adsorption capacity of 185.0 mg g−1 even under 40% relative humidity). Our work provided a low-cost and facile strategy for the synthesis of hierarchical porous and hydrophobic silica materials, and this adsorbent would serve as a promising adsorbent for the elimination of practical volatile organic compounds.

Self-cleaning and friction-resistant superhydrophobic and oleophilic cotton for separation of stable emulsified oil

The separation of emulsified oils containing surfactants from conventional materials poses challenges, thus necessitating the development of recyclable materials capable of absorbing such emulsified oils. The focus of this work is to prepare fabricate wettable cotton fabric (defined as P-GMA/SiO2/OA cotton) with demulsification ability through various strategies (polymer reduces porosity; octadecylamine provides hydrophobicity and lipophilicity; nanoparticles amplify wettability). The process involved the application of polymer glycidyl methacrylate onto the surface of untreated cotton through grafting. Subsequently, super hydrophobic silica was imprinted onto the treated surface, followed by the grafting of octadecylamine. In addition to superhydrophobicity and oleophilicity, the resulting P-GMA/SiO2/OA cotton exhibited exceptional mechanical stretching resistance, with a tensile strength measuring approximately 24.1 MPa. Additionally, it demonstrated resistance to both acidic and alkaline environments, as well as the ability to self-clean. P-GMA/SiO2/OA cotton exhibited the ability to separate layered oil mixture containing heptane, octane, undecane, dodecane and dichloromethane. Even after 500 cycles of oil absorption and desorption, the separation efficiency of the P-GMA/SiO2/OA cotton for the five different types of oil remained greater than 99.2 %. The P-GMA/SiO2/OA cotton has also showed excellent performance in the separation of water-in-oil emulsions. This modified cotton has practical utility for the separation of surfactant-containing emulsified oil under actual operating conditions.

Effect of Drying Control Agent on Physicochemical and Thermal Properties of Silica Aerogel Derived via Ambient Pressure Drying Process

This paper presents the effect of drying control agents on the physicochemical and thermal properties of hydrophobic silica aerogels derived via the ambient pressure drying (APD) method by a surface silylation using a TMCS/n-hexane mixture. The structural and physicochemical properties of synthesized DMF-modified and unmodified hydrophobic silica aerogels were characterized using Brunauer–Emmett–Teller (BET) analysis, thermo-gravimetric analysis, FT-IR, and Raman spectroscopic techniques. Based on the obtained results, the differences in structure between samples before and after a surface silylation and the effect of drying control agents were documented. The structural measurements confirmed the efficient silylation process (TMCS/n-hexane), as well as the presence of DMF residues of hydrogen bonded with unreacted Si-OH silanol groups within the silica backbone after surface modification. Based on TG analysis, it was found that DMF addition improves thermal resistance (up to 320 °C) and hydrophobic character of prepared aerogel. Modification of the silica aerogel synthesis process by DMF also resulted in a significant increase in BET—the specific surface area, for the unmodified aerogel was ~828 m2/g, and for the DMF-modified aerogel more than 1200 m2/g—much higher than the value of silica aerogels available on the market.

Facile Synthesis of Polymer-Reinforced Silica Aerogel Microspheres as Robust, Hydrophobic and Recyclable Sorbents for Oil Removal from Water.

With the rapid development of industry and the acceleration of urbanization, oil pollution has caused serious damage to water, and its treatment has always been a research hotspot. Compared with traditional adsorption materials, aerogel has the advantages of light weight, large adsorption capacity and high selective adsorption, features that render it ideal as a high-performance sorbent for water treatment. The objective of this research was to develop novel hydrophobic polymer-reinforced silica aerogel microspheres (RSAMs) with water glass as the precursor, aminopropyltriethoxysilane as the modifier, and styrene as the crosslinker for oil removal from water. The effects of drying method and polymerization time on the structure and oil adsorption capacity were investigated. The drying method influenced the microstructure and pore structure in a noteworthy manner, and it also significantly depended on the polymerization time. More crosslinking time led to more volume shrinkage, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution and more compact network. Notably, the hydrophobicity increased with the increase in crosslinking time. After polymerization for 24 h, the RSAMs possessed the highest water contact angle of 126°. Owing to their excellent hydrophobicity, the RSAMs via supercritical CO2 drying exhibited significant oil and organic liquid adsorption capabilities ranging from 6.3 to 18.6 g/g, higher than their state-of-the-art counterparts. Moreover, their robust mechanical properties ensured excellent reusability and recyclability, allowing for multiple adsorption-desorption cycles without significant degradation in performance. The novel sorbent preparation method is facile and inspiring, and the resulting RSAMs are exceptional in capacity, efficiency, stability and regenerability.

Hydrophobic Silica Microcavities with Sustainable Nonlinear Photonic Performance.

Ultrahigh quality factor (Q) microcavities have been emerging as appealing compact photonic platforms for various applications. The Q factor plays a critical role in determining the nonlinear optical performance of a microcavity. However, a silica microcavity suffers from severe degradation of its Q value over time during storage or use in air due to the accumulating surface absorption loss, which would deteriorate their nonlinear photonic performance. Here, we report a new type of ultrahigh Q silica microcavity that effectively prevents Q degradation over time. The Q values of the devices remain unchanged over time under storage in air. Optical frequency combs are generated with sustainable ultralow threshold performance over the course of time from the devices in open air. This approach would greatly facilitate ultrahigh Q silica-based photonic devices for next generation photonic applications.

Biomimetic super slippery surface with excellent and durable anti-icing property for immovable heritage conservation

The formation and accumulation of ice on solid surface is not only a potential threat to our daily life, but also a hazard to cultural heritages, such as murals, grottoes, monuments, ancient buildings. Inspired by slippery inner surface of Nepenthes, slippery liquid-infused porous surfaces (SLIPSs) for anti-icing attract a lot of attention recently. In this work, dip-coating approach is utilized to create a hydrophobic silica layer grafted with long-chain organic molecules. After infusing the oil phase, a three-layer Nepenthes-like structure is formed. The SLIPS shows excellent anti-icing property. It reduces the ice-surface adhesion strength to 0 kPa on non-porous surface and 6.83 kPa on porous surface (sandstone from Yungang Grottoes) respectively. After 35 icing/de-icing cycles, the SLIPS still shows good anti-icing ability. Our results show that the middle long-chain organic layer not only enhances the surface hydrophobicity but also increases its affinity with the oil phase to reduce lubricating oil loss, thus increasing its anti-icing durability. When the anti-icing ability decreases with time, simple re-infusing the oil phase can easily restore the anti-icing performance to its original level. The SLIPSs prepared in this work show outstanding hydrophobicity, ice repellency, durability and satisfying water vapor permeability on treated porous sandstones, which makes it potential to protect immovable cultural heritages from ice hazard.

Silica Encapsulation of Hydrophobic Optical NP-Embedded Silica Particles with Trimethoxy(2-Phenylethyl)silane.

Nanoparticles (NP) with optical properties embedded silica particles have been widely used in various fields because of their unique properties. The surfaces of optical NPs have been modified with various organic ligands to maintain their unique optical properties and colloidal stability. Among the surface modification methods, silica encapsulation of optical NPs is widely used to enhance their biocompatibility and stability. However, in the case of NPs with hydrophobic ligands on the surface, the ligands that determine the optical properties of the NPs may detach from the NPs, thereby changing the optical properties during silica encapsulation. Herein, we report a generally applicable silica encapsulation method using trimethoxy(2-phenylethyl)silane (TMPS) for non-hydrophilic optical NPs, such as quantum dots (QDs) and gold NPs. This silica encapsulation method was applied to fabricate multiple silica-encapsulated QD-embedded silica NPs (SiO2@QD@SiO2 NPs; QD2) and multiple silica-encapsulated gold NP-embedded silica NPs labeled with 2-naphthalene thiol (SiO2@Au2-NT@SiO2). The fabricated silica-encapsulated NPs exhibited optical properties without significant changes in the quantum yield or Raman signal intensity.

Green preparation of composite hydrogel coated hydrophobic long-chain carboxylic acid-bonded silica microspheres for mixed-mode chromatography

Combining composite hydrogel with silica gel can endow hydrogel with new application possibilities. In this work, polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were combined into a composite hydrogel, which was then wrapped on the surface of 1-undecenoic acid (UA) bonded silica microspheres. As a result, a novel PVP/PVA composite hydrogel-functionalized silica stationary phase (PVP/PVA@Sil-UA) was prepared by a green and facile method. Specifically, the thiol-ene click reaction was preferentially used to bond a hydrophobic long-chain carboxylic acid (UA) on the surface of thiolated silica gel in deep eutectic solvent, which was able to provide abundant hydrogen bonding sites for the further coating of PVP/PVA composite hydrogel. The hydrophobic long alkyl chain not only improved the separation selectivity, but also effectively alleviated the swelling of hydrogel. It was discovered that the prepared PVP/PVA@Sil-UA showed outstanding separation performance for a wide range of samples. The study of retention behavior proved that the PVP/PVA@Sil-UA was a mixed-mode chromatographic stationary phase, possessing hydrophilic and hydrophobic retention characteristics. In summary, an eco-friendly method was applied to realize the effective combination of composite hydrogel and SiO2 due to the fact that no harmful organic solvents were used in the preparation process, which provided a novel idea for the application of composite hydrogel in the field of chromatographic separation.

Controllable Construction and Corrosion Resistance Mechanism of Durable Superhydrophobic Micro-Nano Structure on Aluminum Alloy Surface

Aluminum alloy corrosion resistance could be improved by micro-nanostructures on superhydrophobic surfaces, but inadequate mechanical stability remains a bottleneck concern in the sector. Herein, femtosecond laser processing and spray modification techniques are employed to fabricate “armor-style” micro-nanostructures on aluminum alloy surfaces. The construction of durable superhydrophobic surfaces was controllably constructed using this strategy. Applying a spray of hydrophobic nano silica onto the surface of aluminum alloys is an effective method for creating a low surface energy coating, while the femtosecond laser-processed “armor-style” micro-nano structure offers additional adhesion sites for the hydrophobic nano-silica. The findings indicated that the treated surface’s contact angle (CA) reached 152.5° while the slide angle (SA) was only 2.3°, exhibiting favorable superhydrophobic performance. Being worn 100 times with 400# sandpaper, the superhydrophobic surface retained a contact angle above 150°. Electrochemical tests demonstrated significant reductions in the self-corrosion current of superhydrophobic surfaces. Meanwhile, the impedance increased significantly, showing good thermal, mechanical, and chemical stability, enabling better sustainable use of aluminum alloys. These results will serve as a theoretical foundation for the surface protection of aluminum alloys.