A Facile Method for Fabrication of Hybrid Hydrophobic-Hydrophilic Surfaces on Anodized Aluminum Template by Electrophoretic Deposition

Fabrication of organic copper phthalocyanine nanowire arrays via a simple AAO template-based electrophoretic deposition

Porous materials have become a burgeoning research interest in materials science because of their intrinsic porous characteristics, versatile chemical compositions, and abundant functionalities. Re...

Preparation of YSZ film by EPD and its application in SOFCs

Structural and optical properties of ZnO films grown on the AAO templates

The reduction of the internal resistance by the accelerations of Li+ transport and electron transfer promotes the high-speed charge/discharge of lithium ion batteries (LIBs). Recently, the improving charge/discharge has been attempted by exploiting model porous electrodes which have mesoporous structures such as anodic aluminum oxide (AAO) [1]. AAO is a suitable template for the preparation of the multi layered structures using its regular nanopore array. TiO2 thin films have potential application in the negative electrodes of LIBs, so we prepared the SiO2 or TiO2/AAO nanocomposite by the liquid phase deposition (LPD) procedure in this work. The LPD method involves a metal oxide and hydroxide thin films synthetic procedure using the hydrolysis equilibria reactions of metal-fluoro complexes as follows; (Hydrolysis reaction) MF x (x-2n)- + H2O → MO n + xF- + 2nH+ (F- scavenging reaction) Al3+ + 6HF → H3AlF6 + 3/2H2 Previously, TiO2 was deposited on the surface of AAO mesopores by the LPD within 250 nm, and in this study, the TiO2 thin film onto AAO mesopore wall which has the extreme small diameter, i.e., ca. 20-40 nm, was prepared by the LPD. In this research, the achievement of the LPD reaction at 0 °C or less by the use of the H2O/EtOH mixed solvent and the deposition of oxide thin film to mesopore inner wall owing to the decrease of the LPD reaction activity under low temperature were executed. Furthermore, the specific ion conductivity of the electrolyte solution in the mesopore channels in the prepared TiO2/AAO nanocomposites was evaluated. AAO membranes were prepared by two-step anodization as previous report [1,2]. AAO template whose thichness is ca. 500 m (i.e. the aspect ratio of a AAO membrane thichness to a mesopore diameter is ca. 5000) was dipped in (NH4)2SiF6 or (NH4)2TiF6 solution of various concentration for 0-60 h at -20-40 °C. Prepared SiO2 or TiO2/AAO nanocomposite was used as a separator of a four-electrode cell and an impedance measurement was carried out. LiClO4/EC:DEC = 1:1 (v/v) of 0.5 to 2.5 mol L-1was used as an electrolyte solution. The results of LPD reaction using (NH4)2TiF6 solution of 10 mol L-1 in 1 : 1 (v/v) H2O/EtOH at -20-5 °C (The LPD reaction solution was still liquid-state at -20 °C) for 10 h were shown in Fig. 1. The TiO2 thin film deposition within the deep mesopores without collapse of the mesopore structure was achieved at -13.5 °C. The AAO mesopore structure collapsed because the LPD reaction reactivity was too high at 5 °C, and the TiO2 thin film was not generated because the reactivity was too low at -20 °C. It is suggested that the moderate decrease in the LPD reaction activity by using an aqueous/organic solvent mixture was necessary to achieve oxide thin films deposition on the AAO mesopore wall, while retaining the AAO mesoporous structure. The Nyquist plots for four-electrode cells using SiO2 or TiO2/AAO nanocomposites show two semicircles for each nanocomposite. The lower frequency region of the semi-circle was assigned as ion transport resistance in the SiO2 and TiO2 modified mesopore walls, and the fitting of the semicircle in the low frequency region, the specific conductivity in the pore was calculated. For a LiClO4 solution of 0.5-2.5 mol L-1, the specific Li+ ion conductivities after SiO2 or TiO2 thin film coating by LPD in the mesopore of the AAO nanocomposites was compared with those without thin film coating (i.e. as-prepared AAO). The conductivity for the TiO2/AAO nanocomposite is 3 times that for as-prepared AAO, whereas that the conductivity for the SiO2/AAO nanocomposite is similar for as-prepared AAO. Even if the concentration was changed, the ratios of the specific Li+ ion conductivity in the SiO2 or TiO2 modified mesopore to the electrolyte solution and as-prepared AAO were almost constant. These activation energies of Li+ ion conduction in mesopores for each sample are 14.6 (as-prepared AAO), 13.8 (SiO2/AAO), 13.2 kJ mol-1 (TiO2/AAO), respectively. It is suggested that the ionic conduction are influenced by surface electric potential of oxides. This work was supported by CREST, JST. [1] T. Fukutsuka, et al., Electrochim. Acta., 199, 380 (2016) [2] H. Masuda et al., Science, 268, 1466 (1995) Figure 1

ABSTRACTSuperhydrophobic and superoleophilic functionalized electrospun poly(vinylidene fluoride) (PVDF) membranes with water repellence, breathability, and oil‐sorption and oil–water separation properties were achieved with a combination of an electrospinning technique and the chemical vapor deposition of dichlorodimethyl silane. The samples were laterally characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, and Fourier transform infrared spectroscopy. The maximum water contact angle value was 152.0 ± 2.5° for the PVDF nanofibrous membranes with 500 μL of deposited silane (PMS2) obtained under certain conditions. The PMS2 membranes showed 100.0, 93.7, 23.3, 35.0, and 100.0% separation efficiencies forn‐hexane, kerosene, crude oil, frying oil, and toluene, respectively. The understudy membrane exhibited reasonable waterproofness and remarkable breathability (water vapor transition rate = 215.21 g/m2.h). Moreover, the superhydrophobic and superoleophilic nanofibrous membranes also showed good reusability, stability, moderate water‐repellent properties, breathability, antifouling properties, and oil–water separation ability after several cycles. These properties confirmed potential in feasible applications, including protective cloths and in the purification of oil‐polluted water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 47621.

Surface properties of polymeric materials were controlled by fabrication of nano-structure and submicronorder structure of poly(fluoroalkyl acrylate) using the chemical and physical surface modification techniques. The relationship between the ordered structure of fluoroalkyl (R f) groups and water repellency mechanism was precisely investigated by grazing-incidence X-ray diffraction, water contact angle measurements and X-ray photoelectron spectroscopy. It was revealed that poly{2-(perfluorooctyl)ethyl acrylate} (PFA-C8) was crystallized and formed ordered structure to result in high water repellency. Surface nano-texturing onto PFA-C8 film surface was carried out using an anodic aluminum oxide (AAO) membrane as a mold. The nano-texture of AAO mold with a pore diameter of 200 nm was transformed onto the PFA-C8 film surface to fabricate nano-structure, which revealed high water and oil repellency. On the other hand, various types of monomers were grafted on the solid surface through surface-initiated atom transfer radical polymerization to result in high-density polymer brushes. Hydrophobic PFA-C8brush surface revealed a low friction coefficient and a good wear resistance. Water lubrication and low friction were observed on the hydrophilic polymer brush. These polymer brushes were successfully introduced on the commercial fluoropolymer, which has inherent radical initiator functional groups. These results indicated that nano-layer immobilization through surface-initiated polymerization and surface texturing are promising methods to control the surface chemistry and surface structure at dimensions in the nano-meter range.

In this paper we report a simple method that enables the easy fabrication of ordered ZnO nanowire arrays using Anodic Aluminium Oxide (AAO) template. We have used a vacuum injection technique to fill solution into the pores of an AAO template. The AAO template has been fabricated by a two-step anodization process using 0.3 M oxalic acid (H2C2O4) solution under a constant voltage of 40 V. The AAO template formed through this process has been detached from Al substrate via an anodic voltage pulse using perchloric acid (HClO4) solution (70%). The nanowires of ZnO have been synthesized by injecting the saturated Zn(NO3)2 solution into the pores of the detached AAO template using a vacuum pump. The ZnO nanowires synthesized by this technique have been found dense & continuous with uniform diameter throughout the length of the wire. The structural characteristics of AAO template and ZnO nanowires have been studied by Field Emission Scanning Electron Microscope (FESEM), Atomic force microscope (AFM) and Transmission Electron Microscope (TEM).

Ordered High‐Density Si [100] Nanowire Arrays Epitaxially Grown by Bottom Imprint Method

Nano–engineered surfaces inspired by nature of gecko feet and cicada wings were widely mimicked to replicate the architectural nanostructures on various polymer films. These natural surfaces often provide multifunctional properties and advanced material surfaces such as adhesiveness, hydrophobic surfaces, bio–medical applications, nanosensing materials, catalytic scaffold materials, and energy storages. In this study, vertically aligned composite nanostructures (VACNs) of polystyrene (PS)–graphene nanoplatelets (GNPs) (1.0–5.0 wt/wt%) were precisely replicated by thermal nanoimprint with anodic aluminum oxide (AAO) template. Implications of the reinforced nanofiller on nanostructured surface properties including physical, chemical, thermal, and mechanical properties were investigated. The one-dimensional (1D) composite nanostructures of PS–GNPs with the length of 10–70 µm and diameter of 100 nm were fabricated, resulting the enhancement of surface wetting ability in the water contact angle from 87±3o (flat film) increased to 132±2o. The increase in surface properties including friction coefficient, surface durability (See Figure 1, left), surface modulus and hardness of the PS–GNPs nanostructures as compared with the neat PS nanostructure, were also respectively obtained. The glass transition temperature (Tg ) of PS–GNPs nanostructures was shifted toward about 1.0 to 4.0 oC as compared with their bulk composites because of the immobilization of the polymer chain owing to confinement and surface interfacial interaction effects at the nanoscale within graphene and AAO template. Interestingly, it was found that thermal conductivity of PS–GNPs nanostructures became higher than their composite films due to the 1D property caused by the control of in–plane orientation of GNPs nanofiller within AAO (See Figure 1, right). The maximum thermal conduction of 1D nanostructure of PS–GNPs 5.0 wt/wt% up to 1.28 W/m.K can be obtained in this study. Higher thermal stability of the PS–GNPs nanostructures than that of PS nanostructure was also shown.

Imparting Superhydrophobicity to Porphyrinic Coordination Frameworks Using Organotin

Influence of wet etching time cycles on morphology features of thin porous Anodic Aluminum oxide (AAO) template for nanostructure’s synthesis

A porous anodic aluminium oxide (AAO) templates were fabricated on aluminium by electrodeposition method using a two-step anodization process. The AAO templates were anodized in 0.3 M oxalic acid solution by applying a constant voltage of 40V, which was afterward treated with chemical etching process in a mixed solution of 6% phosphoric acid and 1.8% chromic acid, respectively. The temperature was kept constant in 15oC during the anodization process and the anodization time were done between 20 to 60 min. All the samples were characterized using by scanning electron microscopy (SEM) to study the surface morphology of AAO templates. It was found that the pore diameters of AAO templates can be controlled by changing the anodizing time. The influence of the electropolishing were also discussed. Highly uniform self-ordered AAO template were effectively formed from these polished foils via an anodizing process.

A mechanical pressure injection technique has been developed to fabricate uniform metallic nanowires in the pores of anodic aluminum oxide (AAO) template. The AAO template was prepared from general purity aluminum by a two-step anodization followed by heat treatment to achieve highly ordered nanochannels. The nanowires were fabricated by an injection process using a hydraulic pressure method. A mold containing the AAO template and a metal foil was placed inside a vacuum chamber and heated up to the melting temperature of the given metal using a hot plate. The hot chamber was then removed from the hot plate and pressure was applied on the melt through the sliding column of the chamber, using a hydraulic jack to impregnate the molten metal into the nanochannels of the AAO. The nanowires were found to be dense and continuous with uniform diameter throughout their length. Diffraction experiment in the transmission electron microscope revealed that individual nanowires are single crystalline. This paper will present the fabrication process of the AAO template, and the fabrication of Bi nanowires as well as their characterization conducted using SEM, TEM, XRD and DSC.

In this research, the hydroxyapatite (HA) nanoparticles were deposited on sandblasted titanium by electrophoretic deposition method. In this case, isopropanol-acetone suspension with 50/50 ratio was used by using iodine as a dispersant. The suspensions were prepared with various concentrations of iodine (0, 0.2, 0.4, 0.6, and 0.8 g/L). Furthermore, the pH of suspension, the electrical conductivity of the suspension mediums, and the zeta potential, mobility, and particle size distribution of HA nanoparticles were measured in suspensions. In the next step, the optimum content of iodine was determined to provide a sustainable suspension. Then, HA coating was deposited on sandblasted titanium surface. The current density during electrophoretic deposition (EPD) and deposition rate in different voltages were investigated. The microstructure and morphology of the sediments were examined by using FE-SEM and AFM. Finally, the structure and phase composition of the coatings were analyzed by using XRD before and after sintering. Furthermore, the adhesion strength of the coating to the substrate was measured. The results show that 0.6-g/L iodine prepared a stable suspension and the effect of current density and potential on the deposition weight is determined. In additional, the results show a finer and narrower particle size distribution can be observed. Also, adhesion strength of the coatings to the sandblasted titanium surface is about 11 MPa.