Alumina Nanofibers Research Articles

Deposition of iron oxide nanoparticles on mesoporous alumina network by wet-combustion technology

Abstract The physico-chemical functionality within mesoporous networks dictates their performance as magnets, catalysts, and electro-thermal conductive materials. In this work, a method of wet-combustion was developed for functionalization of a mesoporous network of alumina nanofibres by iron oxide nanoparticles. As the basic fuels, urea and glycine were used. Iron nitrate was applied as an oxidant and a precursor of iron. The fuel type and oxidizer-to-fuel ratio dominantly affects the formation of the final product. The yielded wet-combusted product varies from iron (II) oxides [FeAl2O4] with crystallite size of 12 nm when glycine is used to iron (III) oxides [AlFeO3] with crystallite size of 21 nm when urea is used as a fuel. The agglomerates of spherical nanoparticles of γ-Fe2O3 with an average crystallite size less than 15 nm were homogenously distributed throughout the mesoporous alumina network in both cases. The magnetization curves reveal saturation point is around 6.3 emu.g−1 alongside the Fe2O3 coated-mesoporous alumina nanofibers, and 6 emu.g−1 for a transversal field.

Reinforcing experimental resin-composites with synthesized zirconia and alumina nanofibers: evaluation of cuspal flexure, flexural strength, flexural modulus and fracture toughness

Aim: This study evaluated cuspal flexure, flexural strength, flexural modulus and fracture toughness of experimental resin-composites reinforced with zirconia and alumina nanofibers. Zirconia and alumina nanofibers were synthesized by wet electrospinning technique. Characterization of these nanofibers was carried out by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy that confirmed pure forms of zirconia nanofibers (50–100 nm in diameter) and alumina nanofibers (70–100 nm in diameter). Materials and methods: The study was divided into seven groups (n = 10/group) according to the type and percentage of added nanofibers: control group, three groups reinforced with 2, 4 and 6 wt% zirconia nanofibers and more three groups reinforced with 2, 4 and 6 wt% alumina nanofibers. Results: A one-way analysis of variance revealed significant differences between the studied groups (P = 0.000) for all investigated properties. Mean cuspal flexure ranged between 0.13 and 0.36% with markedly lower values for groups with higher percentages of nanofibers. For flexural strength, data ranged between 98 and 168 MPa, for flexural modulus between 7.6 and 17.04 GPa, and for fracture toughness between 1.16 and 3.51 MPa m1/2 with greater values recorded for nanofibers-reinforced groups. Conclusion: Zirconia nanofibers were superior to alumina nanofibers in reducing cuspal flexure and improving the studied mechanical properties.

Effect of Alumina Nanofibers Content on the Microstructure and Properties of ATZ Composites Fabricated by Spark Plasma Sintering

In this work, 3mol.% yttria-stabilized zirconia was used as a matrix for the fabrication of alumina toughened zirconia (ATZ) composites. Alumina nanofibers were reinforcing additives with an amount of 1, 5 and 10wt.%. Fully dense ATZ composites were obtained by spark plasma sintering. Microstructure observations of the composites showed the mixed fracture mode, which favorably affects the fracture toughness. It is shown that the fracture toughness and Vickers microhardness of ATZ composites were significantly improved by the addition of Al2O3 nanofibers compared with monolithic ZrO2. The fracture toughness of composite with 1wt.% nanofibers addition is 4.40MPa·m1/2. The microhardness of composite with 5wt.% nanofibers is 16.75GPa. The toughening and strengthening mechanisms were analyzed.

An Alumina/Polyacrylonitrile Nanofibrous Composite Separator via High-Efficiency Electro-Blown Spinning and Wet-Laid Technologies for Improved Lithium-Ion Batteries

In this study, the alumina (Al2O3) nanofibers and polyacrylonitrile (PAN) nanofibers are respectively prepared by the high-efficiency, low-cost and feasible electro-blown spinning (EBS) technology. Then, the nanofibrous composite membranes composed of Al2O3 nanofibers and PAN nanofibers are manufactured via a simple and convenient wet-laid method for use as separator in lithium-ion batteries (LIBs). The results indicate that the novel nanofibrous composite membranes containing Al2O3 nanofibers own excellent thermal stability, which can effectively improve the battery safety. Furthermore, it is found that, compared with pure PAN and commercial separators, the nanofibrous composite separators show higher porosity, better affinity for liquid electrolyte and lower interfacial resistance by introducing a high dosage of Al2O3 nanofibers of 30 wt%, leading to superior C-rate capability and more stable cycling ability. In addition, the LIBs assembled with 30 wt% Al2O3/PAN separator exhibit high discharge specific capacity of 152.9 mAh/g at the current density of 0.5 C and possess high capacity retention of 83.1% after 200 cycles.

Synthesis and Characterization of Alumina-ChitosanHydroxyapatite Biocomposites for Load Bearing Application

This study investigated the influence of reinforcing hydroxyapatite (HA) with alumina (Al) and chitosan nanofiber (CH) to enhance its usefulness in load bearing application. Commercial alumina was used while chitosan fiber and hydroxyapatite were synthesized from cowry shells and limestone respectively. The developed composites were characterized with a view to assessing theirsuitability for use as medical implants in load bearing capacity. It was observed that the optimum compressive strength obtained was 181.73 MPa, tensile strength of 172.67 MPa, hardness value of 529.21 HV, fracture toughness of 7.42 MPa.m1/2 , elastic modulus of 8.23 GPa and bending strength of 175.51 MPa. Increasing volume fractions of Al-CH resulted in decrease in compressive strength, hardness and elastic modulus of hydroxyapatite while its tensile strength, bending strength and fracture toughness increased. The result obtained from the Fourier Transform Infrared Spectrometry revealed that the intermolecular hydrogen bond and chelate interaction between the constituents contribute to the good mechanical properties of the composite. X-Ray Fluorescence analysis result indicates that their chemical compositions contain ions which are found in the physiological environment. The dispersion of the alumina-chitosan nano fiber in the HA matrix as revealed by the Scanning Electron Microscope micrographs result in the formation of interfaces which activates different mechanisms that improve the strength of HA. The optimum mechanical property was obtained at 20-20-60 Al-CH-HA composite. Hence, this composite will be a suitable material for load bearing application.

Fabrication of Sticky and Slippery Superhydrophobic Aluminum Surfaces Via Pyrophosphoric Acid Anodizing and SAM Modification

Anodizing aluminum in a concentrated pyrophosphoric acid solution (H4P2O7) leads to the formation of numerous anodic alumina nanofibers measuring less than 10 nm in diameter. As the alumina nanofibers are modified with self-assembled monolayer (SAM), the nanofiber-covered aluminum surface exhibits a superhydrophobic behavior with a water contact angle measuring more than 150°. In the present investigation, we demonstrate the fabrication of slippery and sticky superhydrophobic aluminum surfaces covered by the anodic alumina nanofibers. The effect of the nanostructure of the anodic oxide on the adhesion interaction between the water droplet and the surface was investigated by dynamic contact angle measurements. High-purity aluminum specimens (99.99 wt%, 400 µm thick) were ultrasonically degreased in ethanol for 10 min. The specimens were electropolished in a 78 vol% CH3COOH/22 vol% 70%-HClO4 solution (T = 280 K) at a constant voltage of 28 V for 1 min. The electropolished specimens were immersed in a concentrated pyrophosphoric acid solution (74.0 wt%, T = 293 K), and then were anodized at a constant voltage of 50 V using a PC-connected direct-current power supply. After anodizing, the specimens were immersed in a 0.5 mM 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctylphosphonic acid (FOPA) / ethanol solution (T = 313 K) for 24 h to form SAM on the anodic alumina nanofibers. The surface nanomorphology of the anodized specimens was examined by field emission scanning electron microscopy (FE-SEM). The water contact angles on the anodized specimens were measured by an optical contact angle meter. The distilled water droplets were formed on the surface using an auto dispenser and a microsyringe with a flow rate of 2 µL/s, and the advancing and receding contact angles were measured by a charge-coupled device (CCD) camera (frame rate: 10 fps). Figure 1 shows the changes in the advancing and receding contact angles with the anodizing time. Here, the anodic oxide was modified with the FOPA-SAM after anodizing. The advancing contact angle rapidly increased to superhydrophobicity more than 160° by the initial stage of anodizing, and the contact angles were maintained at similar values via the long-term anodizing. In contrast, the receding contact angle was drastically changed with the anodizing time: the contact angle rapidly decreased to approximately 0° in the initial stage of anodizing, rapidly increased to 150° in the middle stage, and then gradually decreased to 0° in the final stage. This complicated behavior was due to the nanostructural surface changes via pyrophosphoric acid anodizing. Figure 2 shows the side views of the 20 µL water droplet on the superhydrophobic aluminum specimens fabricated by pyrophosphoric acid anodizing for a) 4 min and b) 20 min and subsequent FOPA-SAM modification. The water droplet was pinned on the surface anodized for 4 min when it was turned upside down (i.e. a sticky surface). Conversely, the droplet easily rolled off with a small sliding angle on the surface anodized for 20 min (i.e. a slippery surface). Figure 1

Alumina/graphene/Cu hybrids as highly selective sensor for simultaneous determination of epinephrine, acetaminophen and tryptophan in human urine

A highly selective electrochemical sensor representing alumina/graphene/Cu hybrid structure was fabricated by electrodeposition of copper nanoparticles on graphene encapsulated alumina nanofibers and was employed for the simultaneous determination of epinephrine (EP), acetaminophen (AP) and l-tryptophan (Trp) with low instrumental detection limits (LOD) and wide linear ranges. Cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry and chronoamperometry methods were used to study electrochemical properties of the developed electrode. Well-separated oxidation peaks and enhanced peak currents of EP, AP, and Trp were observed owing to the superior conductivity of highly foliated multi-layered graphene and the excellent catalytic activity of Cu nanoparticles. Specifically, the separation of anodic peak potentials for EP-AP, AP-Trp and EP-Trp were 160, 274 and 434 mV vs. SCE, respectively. The peak currents linearly depended on EP, AP and Trp concentrations in the range of 1–1200, 1–700 and 1–1000 μM with LOD of 0.027, 0.012 and 0.009 μM, respectively (Sbk/m = 3). The chemically modified electrode was successfully challenged with some interfering compounds and was evaluated in human urine sample for determination of EP, AP and Trp demonstrating outstanding stability and repeatability. Fabricated sensor is an appropriate candidate for the pharmaceutical applications and clinical investigations.

Синтез и исследование каталитических свойств композиционных материалов на основе ZIF-8 и слоистого оксида алюминия в реакции конденсации бензальдегида с малононитроилом

Синтез и исследование каталитических свойств композиционных материалов на основе ZIF-8 и слоистого оксида алюминия в реакции конденсации бензальдегида с малононитроилом

Effect of Electric Field on Ion Transport in Nanoporous Membranes with Conductive Surface

The effect of an external electric field on the ionic conductivity and selective properties of ceramic membranes based on alumina nanofibers coated with a conductive carbon layer has been studied. It has been shown that the membranes are ideally polarizable in the polarizing voltage range of −500 to +500 mV and, therefore, can be used for implementing switchable ionic selectivity. Experiments have revealed that the membrane resistance decreases with a change in the applied potential from 0 to ±500 mV. It has been shown that the membrane selectivity can be switched from anion to cation by varying the external potential. The surface charge density of the membranes has been determined in terms of the Teorell–Meyer–Sievers model according to the experimental measurements of the membrane potential.

Absorption of Ethylene on Membranes Containing Potassium Permanganate Loaded into Alumina-Nanoparticle-Incorporated Alumina/Carbon Nanofibers.

Ethylene is a natural aging hormone in plants, and controlling its concentration has long been a subject of research aimed at reducing wastage during packaging, transport, and storage. We report on packaging membranes, produced by electrospinning, that act as efficient carriers for potassium permanganate (PPM), a widely used ethylene oxidant. PPM salt loaded on membranes composed of alumina nanofibers incorporating alumina nanoparticles outperform other absorber systems and oxidize up to 73% of ethylene within 25 min. Membrane absorption of ethylene generated by avocados was totally quenched in 21 h, and a nearly zero ethylene concentration was observed for more than 5 days. By comparison, the control experiments exhibited a concentration of 53% of the initial value after 21 h and 31% on day 5. A high surface area of the alumina nanofiber membranes provides high capacity for ethylene absorption over a long period of time. In combination with other properties, such as planar form, flexibility, ease of handling, and lightweight, these membranes are a highly desirable component of packaging materials engineered to enhance product lifetime.

Nanostructural evolution in mesoporous networks using in situ High-Speed Temperature Scanner

Mesoporous networks with a special distribution of functional centers are an important class of high performance materials for catalysts, bioscaffolds, energy conversion and storage systems. Methods of fabrication allowing to control over special distribution of the functional sites of required phases and designed morphology are still of a great challenge. Here, we report a wet-combustion method for functionalization of the mesoporous network of alumina nanofibers with a single fiber diameter of 7 ± 2 nm by Ni-based nanoparticles. The second-scale duration of the combustion process developing high flame temperature (>1000 °C) allows fabrication of mesoporous functional networks with tailored size, morphology and homogeneity of the dopants in a single-stage. The mechanism of the combustion process are studied by in situ high-speed temperature scanner, which continuously records the temperature history and applied power during the process. It readily allows quenching of the samples at a specified point, demonstrates the critical effect of a fuel on the decomposition temperature, combustion enthalpy, functional group, and pH. As a result of the wet-combustion synthesis, aligned double core-shell NiO-NiAl2O4-Al2O3 fibers or NiO nanoparticles deposited onto alumina nanofibers can be formed.

Sol-Gel Synthesis of Nanostructured Alumina Supports for CO Oxidation Catalysts

In present work, a new technique to prepare alumina nanoparticles and nanofibers using a sol-gel method was proposed. A solution combustion method was applied to form a nanostructured catalytically active layer of CuO–Co3O4–CeO2 on the surface of the alumina. The uniform distribution and fine dispersion of active components provide the appropriate activity of the catalysts obtained in a model reaction of CO oxidation. The morphology of nanostructured alumina was found to affect the catalytic behavior. Carbon monoxide conversion was observed at lower temperatures when alumina nanofibers were used as a catalyst support.

Mirror-finished superhydrophobic aluminum surfaces modified by anodic alumina nanofibers and self-assembled monolayers

We demonstrate mirror-finished superhydrophobic aluminum surfaces fabricated via the formation of anodic alumina nanofibers and subsequent modification with self-assembled monolayers (SAMs). High-density anodic alumina nanofibers were formed on the aluminum surface via anodizing in a pyrophosphoric acid solution. The alumina nanofibers became tangled and bundled by further anodizing at low temperature because of their own weight, and the aluminum surface was completely covered by the long falling nanofibers. The nanofiber-covered aluminum surface exhibited superhydrophilic behavior, with a contact angle measuring less than 10°. As the nanofiber-covered aluminum surface was modified with n-alkylphosphonic acid SAMs, the water contact angle drastically shifted to superhydrophobicity, measuring more than 150°. The contact angle increased with the applied voltage during pyrophosphoric acid anodizing, the anodizing time, and the number of carbon atoms contained in the SAM molecules modified on the alumina nanofibers. By optimizing the anodizing and SAM-modification conditions, superhydrophobic behavior could be achieved with only a brief pyrophosphoric acid anodizing period of 3 min and subsequent simple immersion in SAM solutions. The superhydrophobic aluminum surface exhibited a high reflectance, measuring approximately 99% across most of the visible spectrum, similar to that of an electropolished aluminum surface. Therefore, our mirror-finished superhydrophobic aluminum surface based on anodic alumina nanofibers and SAMs can be used as a reflective mirror in various optical applications such as concentrated solar power systems.

Mehanička svojstva hibridnog kompozita UHMWPE/EVA ojačanog vlaknima dobijenim elektropredenjem

Alumina (Al2O3) nano fibers are prepared from an aqueous solution of aluminum hydroxy chloride/poly (vinyl alcohol) (PVA)/water using the electrospinning technique. The weight ratio of aluminum hydroxy chloride/PVA was 5: 1. After calcification of fibers at 1100 ° C, continuous aluminum oxide fibers were obtained from 200 to 800 nm. The fiber morphology is characterized by a scanning electron microscope (SEM). Image analysis software (Image Pro Plus) was used to measure the diameter of the obtained aluminum oxide (Al2O3) fibers. The aim of this paper is to examine the mechanical properties of the hybrid composite, consisting of a polymer matrix (ethylene and vinyl acetate copolymer (EVA)), ultrahigh molecular weight polyethylene fibers (UHMWPE) and Al2O3 fibers obtained by electrospinning. Al2O3 fibers were added in an amount of 1 wt. % as shown by the improvement of the mechanical properties of the matrix and the hybrid composite.

Fibrous alumina-based Ni-CeO2 catalyst: Synthesis, structure and properties in propane pre-reforming

In the present paper we report the synthesis, structural characterization and catalytic properties of alumina nanofibers supported Ni-CeO2 catalyst (Ni-CeO2/ANF) in pre-reforming of propane as a main component of liquefied petroleum gas. Ni-CeO2/ANF catalyst was prepared via template-assisted wet-combustion synthesis. High dispersion and uniform distribution of nickel and ceria species over nanofibers surface were reached. Ni-CeO2/ANF exhibited sufficient activity, stability and coking-resistance in pre-reforming of propane at low steam to carbon ratio and temperatures of 350–425 °C.

Template-Assisted Wet-Combustion Synthesis of Fibrous Nickel-Based Catalyst for Carbon Dioxide Methanation and Methane Steam Reforming.

Efficient capture and recycling of CO2 enable not only prevention of global warming but also the supply of useful low-carbon fuels. The catalytic conversion of CO2 into an organic compound is a promising recycling approach which opens new concepts and opportunities for catalytic and industrial development. Here we report about template-assisted wet-combustion synthesis of a one-dimensional nickel-based catalyst for carbon dioxide methanation and methane steam reforming. Because of a high temperature achieved in a short time during reaction and a large amount of evolved gases, the wet-combustion synthesis yields homogeneously precipitated nanoparticles of NiO with average particle size of 4 nm on alumina nanofibers covered with a NiAl2O4 nanolayer. The as-synthesized core-shell structured fibers exhibit outstanding activity in steam reforming of methane and sufficient activity in carbon dioxide methanation with 100% selectivity toward methane formation. The as-synthesized catalyst shows stable operation under the reaction conditions for at least 50 h.

Periodic Functionalization of Graphene‐Layered Alumina Nanofibers with Aromatic Thermosetting Copolyester via Epitaxial Step‐Growth Polymerization

AbstractIn situ epitaxial step‐growth polymerization driven interfacial functionalization of aromatic thermosetting copolyester (ATSP) with multilayered graphene wrapped alumina nanofiber surface is reported. During a thermal condensation polymerization, ATSP dip‐coated fiber strands develop a nanohybrid shish–kebab structure with periodically assembled and off‐surface grown micrometer‐scale lamella ATSP domains. A mechanism combining the Plateau–Rayleigh instability, the Marangoni effect, and the epitaxial growth phenomena is proposed to elucidate controlling parameters in the process. X‐ray diffraction measurements clearly demonstrate the formation of a mesomorphic lamella phase not present within either the neat ATSP or pristine fiber samples. Results of solid‐state nuclear magnetic resonance and thermogravimetric analysis reveal the development of an interfacial coupling between the graphene‐coated ceramic nanofibers and the ATSP matrix.

Ultra-sensitive voltammetric simultaneous determination of dopamine, uric acid and ascorbic acid based on a graphene-coated alumina electrode

The authors describe the fabrication of an interconnected edge-exposed graphene nanostructure via chemical vapor deposition (CVD) of foliated graphene onto a network of alumina nanofibers. The fibers such obtained are shown to enable ultra-sensitive voltammetric determination of dopamine (DA), uric acid (UA) and ascorbic acid (AA). The electrode displays powerful and persistent electro oxidative behavior and excellent electron transport properties. Cyclic voltammetry and differential pulse voltammetry demonstrate excellent selectively and sensitivity for AA, DA and UA, with typical peaks at −0.08 V, +0.19 V, and +0.34 V (vs. SCE), respectively. Under optimum conditions, the calibration plots are linear in the 1–80 μM range for DA, in the 1–60 μM range for UA, and in the 0.5–60 μM range for UA, with detection limits of 0.47 μM, 0.28 μM and 0.59 μM, respectively. The sensor was successfully applied to the simultaneous determination of DA and UA in the presence of AA in spiked urine sample.

Fabrication of Superhydrophobic Aluminum Surfaces By Pyrophosphoric Acid Anodizing and SAM Modification

Anodizing is one of the most important surface finishing techniques for aluminum and its alloys in various industrial applications. Recently, we reported a novel anodic aluminum oxide formed via anodizing in a new electrolyte, pyrophosphoric acid solution (H4P2O7). Pyrophosphoric acid anodizing leads to the formation of numerous alumina nanofibers measuring less than 10 nm in diameter on the aluminum substrate. In the present investigation, we report the fabrication of a superhydrophobic aluminum surface modified by anodic alumina nanofibers and self-assembled monolayers (SAMs). High-purity aluminum specimens (4N, 400 µm thick) were ultrasonically degreased and electropolished. The specimens were immersed in a concentrated pyrophosphoric acid solution (74.0 wt%, T = 273–293 K), and then were anodized at a constant voltage of 10 to 75 V to form anodic alumina nanofibers. After anodizing, the specimens were immersed in 5 mM n-alkylphosphonic acid / ethanol solutions (Ti= 293–313 K) for up to 48 h to form SAMs on the anodic alumina nanofibers. Seven types of n-alkylphosphonic acid with different chain lengths were used for SAM-modifications. The surface nanomorphology of the anodized specimens was examined by field emission scanning electron microscopy (FE-SEM). The water contact angles on the specimens were measured by an optical contact angle meter. Distilled water droplets (2–3 µL volume) were placed on the specimens, and the contact angles of the droplets were measured by a charge-coupled device (CCD) camera. Figure 1 shows the appearances of water droplets on the a) electropolished aluminum surface and b) nanofiber-covered aluminum surface after TDPA-SAM modifications (Ti = 313 K, ti= 24 h). The contact angle greatly increased from approximately 110° to 160° by pyrophosphoric acid anodizing. Because the pyramidal alumina bundles were formed on the aluminum specimen by pyrophosphoric acid anodizing (Figure 2), the water droplet was supported by the top of the pyramidal alumina bundles with TDPA-SAMs, and a large amount of air was trapped in the spaces between the alumina bundles. As the aluminum specimens were anodized at the low temperature of 273 K, the contact angle increased with anodizing time, and the aluminum surface exhibited a superhydrophobic behavior after anodizing for 4 h. However, the contact angle gradually decreased after that time, and the superhydrophobic angles above 150° no longer appeared after the excess anodizing process. High-aspect-ratio anodic alumina nanofibers then bent under their own weight, and the aluminum surface was completely covered by the long alumina nanofibers. The contact angle decreases by long-term anodizing at low temperature because of the loss of the air trapping space caused by the excess growth of the alumina nanofibers. Figure 1

Superhydrophilic and Superhydrophobic Aluminum Alloys Fabricated By Pyrophosphoric Acid Anodizing

Introduction Recently, we demonstrated the fabrication of anodic alumina nanofibers via anodizing in a new electrolyte, pyrophosphoric acid (H4P2O7). Interestingly, the aluminum surface covered by the anodic alumina nanofibers exhibited a superhydrophilic behavior with a contact angle measuring less than 10°. In the present investigation, we described the fabrication of superhydrophilic and superhydrophobic aluminum alloys via pyrophosphoric acid anodizing and subsequent SAM modification. Experimental Two kinds of aluminum specimens (5N aluminum and 3004/1N30/8021 aluminum alloys) were ultrasonically degreased and chemically polished. The specimens were anodized in a concentrated pyrophosphoric acid solution at a constant cell voltage of 25-75 V for 60 min. The anodized specimens were immersed in a 0.5 mM fluorinated phosphoric acid SAM (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctylphosphonic acid: FOPA)/ethanol solution at 293-323 K for 48 h. anodized specimens were examined by field emission scanning electron microscopy (FE-SEM). The water contact angles were measured by an optical contact angle meter (2 µL in water volume for hydrophilic measurements and 4 µL for hydrophobic measurements). Results Anodizing of aluminum and its alloys in a pyrophosphoric acid solution caused the formation of numerous anodic alumina nanofibers on the aluminum surface. During anodizing of aluminum alloys, many intermetallic compounds were exposed to the surface with anodizing time increase, and the nanofiber-tangled intermetallic particles were formed on the surface. The contact angle decreased with the anodizing time, and the nanofiber-covered aluminum alloys exhibited a superhydrophilic behavior measuring less than 3° in the contact angle (Figure 1, anodizing voltage: Ua = 75 V). As the surface of the nanofiber-covered aluminum alloys was modified with fluorinated phosphoric acid SAMs (solution temperature: Tim = 293-313 K), the contact angle drastically increased with the immersion time and temperature. These aluminum alloys exhibited a superhydrophobic behavior measuring more than 150° (Figure 2). Figure 1. Changes in the water contact angle, θ, with the anodizing time, ta, on the 5N aluminum and 3004 aluminum alloy surfaces after anodizing in a pyrophosphoric acid solution (293 K) at 75 V. Figure 2. Changes in the water contact angle, θ, with the immersion time, tim, on the nanofiber-covered aluminum alloys (3004). The specimens were anodized at 75 V for 10 min, and then were immersed in a 0.5 mM FOPA-SAM/ethanol solution. Figure 1