Photolithographic Approaches for Fabricating Highly Ordered Nanopatterned Arrays

In this work, we report that large area metal nanowire and polymer nanotube arrays were successfully patterned by photolithographic approach using anodic aluminum oxide (AAO) templates. Nanowires were produced by electrochemical deposition, and nanotubes by solution-wetting. The highly ordered patterns of nanowire and nanotube arrays were observed using scanning electron microscopy (SEM) and found to stand free on the substrate. The method is expected to play an important role in the application of microdevices in the future.     

Internal morphologies of diblock copolymer nanorods fabricated from regular and irregular pores of anodized aluminum oxide templates

Internal nanostructures in nanorods of polystyrene-poly(4-vinyl pyridine) (PS-PVP) diblock copolymers fabricated from pores having regular or irregular contours in AAO templates were investigated by cross-sectional transmission electron microscopy. When nanorods of PS-PVP copolymers were produced from pores with regular contours, a typical morphology of concentric cylinders was observed due to the strong affinity of the PVP block to the surface of the AAO pores. In the case of PS-PVP nanorods obtained from pores with irregular contours, a concentric cylindrical morphology was not induced. Instead, a nanostructure of lamellae mostly parallel to the axis of the nanorods was observed with a similar period of lamellae to the bulk lamellar period. In addition, nanorods having a functional coaxial nanostructure were fabricated by synthesizing Au nanoparticles in concentric cylinders of the nanorods to demonstrate the utilization of self-assembled internal nanostructures in nanorods.     

Y型孔洞阳极氧化铝模板的制备研究

阳极氧化铝(AAO)模板由于制备简单,成本较低,其孔径大小具有可控性等优点,是制备形状均匀、有序纳米电子材料的理想无机模板。直流恒压下,在0.3 M草酸溶液中对铝实施两步阳极氧化,并在第二次阳极氧化中途降低电压为初始电压的1/2获得Y形孔洞的氧化铝模板。利用扫描电子显微镜(SEM)对模板进行表征,结果表明:氧化铝模板高度有序,主干孔径约90 nm,分支孔径为(42±5)nm。     

Nanostructured materials prepared by use of ordered porous alumina membranes

We report on three different methods to prepare nanostructured materials using highly ordered porous alumina membranes as templates: (1) firstly, a new and simple method, termed as the paired cell method, was developed for the preparation of inorganic nanowires. Several kinds of inorganic nanowires were synthesized using this method. The structure and composition of these nanowires were determined by field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. (2) Secondly, highly ordered platinum nanowire arrays were prepared by electrochemical method with the help of porous alumina membrane templates. The structure and composition of these nanowire arrays were also characterized by various experimental techniques. The electrochemically active surface area of the nanowire arrays was determined by cyclic voltammetry based on hydrogen adsorption. Results showed that the platinum nanowire arrays exhibited a large surface area. (3) Finally, we also present a simple and reliable procedure for the preparation of highly ordered metal nanohole and nanopillar arrays, based on the anodic oxidation of aluminum and vacuum evaporation technology. The field emission scanning electron microscopic images revealed that these metal nanostructure arrays were highly ordered over a large area. The nanoimprinting of aluminum surfaces using the as-prepared chromium nanopillar arrays was demonstrated, resulting in periodic indentation on the aluminum surface.     

Fabrication and optical characterization of poly(2,5‐di‐n‐butoxyphenylene) nanofibril arrays

Anodic aluminum oxide (AAO) membrane can be used as template for the synthesized nanostructures. In this article, we have prepared the AAO membrane by using electrooxidation of aluminum substrate in phosphoric acid, and fabricated poly(2,5‐di‐n‐butoxyphenylene) (BuO–PPP) nanofibril arrays by oxidative coupling polymerization of 1,4‐di‐n‐butoxybenzene (DBB) within the pores of the AAO template membrane. The detailed molecular structure of the polymer nanofibrils was characterized by using infrared and ¹H nuclear magnetic resonance spectra, and estimated to consist of almost equal fractions of 1,4‐ and 1,3‐ linkages. We have used transmission electron microscopy, scanning electron microscopy, and atom force microscopy to confirm the morphologies and images of the AAO template membrane and the fabricated nanometer scale of BuO–PPP nanofibril arrays. The experimental results demonstrated that the pores of the AAO membrane were regular and uniform, and parallel each other, and the BuO–PPP chains in the narrowest template‐synthesized nanofibrils were oriented parallel to the porous axes of the AAO membrane and perpendicular to the surface of the aluminum substrate. The polymer chain orientation was partially responsible for the enhanced conductivity. The ultraviolet absorption spectrum of the BuO–PPP nanofibril arrays shown that the polymer contains a better extended π‐conjugation system along poly‐(p‐phenylene) backbone, which resulted in longer wavelength shift of the absorption band, the absorption maxima were located at 258 nm (E₁ absorption band) and 332 nm (E₂ absorption band), respectively. Photoluminescence spectrum of the BuO–PPP nanofibril arrays exhibited a blue emission. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 425–430, 2004     

Dynamic study of polystyrene-block-poly(4-vinylpyridine) copolymer in bulk and confined in cylindrical nanopores

AAO template is highly recommended to nanostructure polymers and to study polymer properties under confinement. The dynamic properties of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) under confinement using broadband dielectric spectroscopy are investigated in this work and the results compared to those of the bulk. Anodized aluminum oxide (AAO) membranes, having pore diameters from tens to hundreds of nanometers in size, were used to confine PS-b-P4VP. Moreover, the influence of gold nanoparticles (AuNPs) in the copolymer matrix was also studied. The morphology and structure of the bulk copolymer and the copolymer confined in the AAO templates were characterized by transmission electron microscopy, scanning electron microscopy and Small Angle X-Ray Scattering. For PS-b-P4VP in bulk, dielectric relaxation techniques allowed studying selectively the P4VP segmental dynamics within the diblock. At high temperature this copolymer presents a dominant peak (MWS relaxation), most likely originated by the relatively high conductivity combined with the presence of interfaces emerging in the nanostructured samples. Moreover, a pronounced β-relaxation is observed for the copolymer compared with that of pure P4VP. This is likely due to a non-negligible contribution from the α-relaxation of the PS component. The γ-relaxation is markedly different in the copolymer, which is evidenced by a distinct temperature dependence of the resulting relaxation times. When the copolymer is embedded in alumina nanopores with small pore diameters (25 and 35 nm) there are significant changes, where the tendency is going to a faster dynamics when the pore diameter decreases more likely related to the relevance of surface effects. The presence of the AuNPs in the system enhances this effect. These results are in agreement with segregated structures found in the block copolymer by TEM and SAXS.     

A mini review: Functional nanostructuring with perfectly-ordered anodic aluminum oxide template for energy conversion and storage

Nanostructures have drawn great attentions for functional device applications. Among the various techniques developed for fabricating arrayed nanostructures of functional materials, nanostructuring technique with porous anodic aluminum oxide (AAO) membrane as templates becomes more attractive owing to the superior geometrical characteristics and low-cost preparation process. In this mini review, we summarize our recent progress about functional nanostructuring based on perfectly-ordered AAO membrane to prepare perfectly-ordered nanostructure arrays of functional materials toward constructing high-performance energy conversion and storage devices. By employing the perfectly-ordered AAO membrane as templates, arrayed nanostructures in the form of nanodot, nanorod, nanotube and nanopore have been synthesized over a large area. These as-obtained nanostructure arrays have large specific surface area, high regularity, large-scale implementation, and tunable nanoscale features. All these advanced features enable them to be of great advantage for the performance improvement of energy conversion and storage devices, including photoelectrochemical water splitting cells, supercapacitors, and batteries, etc.

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Electrochemical copolymerization of pyrrole and thiophene nanofibrils using template‐synthesis method

Copolymer nanofibrils composed of pyrrole and thiophene were prepared by synthesizing the desired polymer within the pores of microporous anodic aluminum oxide (AAO) template membranes. The copolymer nanofibrils were photographed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for microstructure analyses. The results of the SEM and TEM revealed that the copolymer nanofibrils obtained had uniform and well‐aligned arrays and their diameter and length could be controlled by changing the aspect ratios of the AAO membrane. The results of cyclic voltammetry and IR spectrometry indicated that polypyrrole and polythiophene were both involved in the copolymer. The nanofibrils that were obtained were identified as copolymers rather than composites. The influence of the applied polymerization potential on the synthesis of copolymer nanofibrils was investigated. The higher potential favored the incorporation of thiophene units into the copolymer nanofibrils. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2403–2407, 2002     

One‐dimensional polymer nanofiber arrays with high aspect ratio obtained by thermal nanoimprint method

Polymer surface modification that mimicks natural behaviors has been a subject of great interest. Fabrication of polymer nanofiber arrays with various applications has been studied intensively. Avoidance of chemical solvents, reduction of processing time, improvement of the nanofiber size distribution and aspect ratios, and improvement of reproducibility have been sought for industrial value creation. This study examines an alternative fabrication methods for polymer nanofiber arrays using a combination of anodic aluminum oxide (AAO) nanoporous template and thermal nanoimprinting lithography for simple, precise processing. Based on those results, nanofiber arrays were fabricated with 40‐µm‐thick film and 50–100 nm fiber diameter polystyrene (PS) and polypropylene (PP). For this study, 50‐nm diameter PS nanofibers with 50 µm maximum length and a maximum aspect ratio of 1,000 were produced in addition to PP nanofibers having 130 µm maximum length and an aspect ratio of 2,600. The nanofiber lengths were affected considerably by molten polymer flow related to imprint processing conditions, polymer properties, AAO properties, and surface wettability between AAO and molten polymers. Moreover, AAO nanoconfinement demonstrated molecular orientation alignment of polymers that affect thermal properties, crystallinity, and mechanical properties of the obtained polymer nanofiber arrays. POLYM. ENG. SCI., 57:214–223, 2017. © 2016 Society of Plastics Engineers     

Fe21Ni79合金纳米线阵列的制备与磁性

用交流电化学沉积方法,在多孔铝阳极氧化膜的柱形孔内制备直径约60 nm,长度约为9.7 μm的Fe₂₁Ni₇₉合金纳米线.采用扫描电镜、透射电镜、X射线衍射仪和振动样品磁强计对纳米线的形貌 、结构和磁学性质进行了测试.结果表明,Fe₂₁Ni₇₉纳米线排列有序,长径比可控,合金呈fcc结构.当将其在外磁场下进行垂直磁化时,磁滞回线出现较高的矩形比0.86,矫顽力达1203Oe.且随着退火温度升高,矫顽力迅速增大,500℃时达到最大值1315Oe,之后又随退火温度的升高而下降.矩形比也呈现类似的变化规律.     

用多孔氧化铝膜为模板制备Fe磁性纳米线

铝在0．3mol／L草酸或硫酸介质中经过阳极氧化,得到不同孔径的多孔氧化铝模板,在此模板中电解沉积的Fe纳米线排布规则、有序,长径比约为150。根据测量的磁滞回线,可以看到制备的铁纳米线具有较大的磁各向异性,其垂直方向具有较高的矫顽力。     

Janus composite nanorings by combinational template synthesis and skiving micro-process

Janus composite nanorings are fabricated by skiving the corresponding arrayed nanotubes. Polymer nanotubes and their arrays are polymerized from the pore surface via ATRP inside porous anodic aluminium oxide membrane (AAO) templates. By a selective partial modification of the interior surface of the polymer nanotubes followed by a favorable growth of other materials, double-shelled composite nanotubes and their arrays are derived. After skiving, the corresponding Janus composite nanorings are obtained with two different compositions compartmentalized onto both interior and exterior surfaces, respectively. Characteristic dimension, microstructure and composition of the Janus composite nanorings can be tuned. As examples, Janus composite nanorings of sulfonated PS/PS, titania/PS, silica/PS and PANi/PS are prepared.     

New Colloidal Lithographic Nanopatterns Fabricated by Combining Pre-Heating and Reactive Ion Etching

We report a low-cost and simple method for fabrication of nonspherical colloidal lithographic nanopatterns with a long-range order by preheating and oxygen reactive ion etching of monolayer and double-layer polystyrene spheres. This strategy allows excellent control of size and morphology of the colloidal particles and expands the applications of the colloidal patterns as templates for preparing ordered functional nanostructure arrays. For the first time, various unique nanostructures with long-range order, including network structures with tunable neck length and width, hexagonal-shaped, and rectangular-shaped arrays as well as size tunable nanohole arrays, were fabricated by this route. Promising potentials of such unique periodic nanostructures in various fields, such as photonic crystals, catalysts, templates for deposition, and masks for etching, are naturally expected.     

Nanostructured poly(3-hexylthiophene-2,5-diyl) films with tunable dimensions through self-assembly with polystyrene

Poly(3-hexylthiophene-2,5-diyl) is among the most widely used conjugated polymers for opto-electronic applications. To enhance its properties, researchers have attempted to nanostructure this polymer using various processes including breath figure arrays, nanolithography and elaborated organic synthesis. We here demonstrate a simple process to nanostructure the conjugated polymer using self-assembly with polystyrene and selective removal of one of the phases. The influence of the molecular weight of each polymer on the thin film morphology was systematically studied by atomic force microscopy. Using this approach, we observe two types of nanostructure, namely, nanoporous and nanoisland structures, of which the dimensions can be tuned by modifying the molecular weight of each polymer in the blend. This simple process introduces a cost-effective alternative to produce thin films of conjugated polymer with average nano-features from 100 nm up to 500 nm which could be used in a wide range of applications.     

Synthesis and characterization of aniline and o‐toluidine conducting copolymer microtubes with the template‐synthesis method

Copolymer microtubes composed of aniline and o‐toluidine were prepared through the synthesis of the desired polymer within the pores of a microporous anodic aluminum oxide (AAO) template. Scanning electron microscopy and transmission electron microscopy revealed that the obtained copolymer microtubes had uniform and well‐aligned arrays, and the aspect ratios of the AAO membranes could be controlled through their diameter and length. Infrared spectrometry and X‐ray photoelectron spectroscopy supported the surface analysis for the microtubes and also proved the formation of copolymers. Ultraviolet–visible/near‐infrared spectra proved that the doping effect decreased with an increase of o‐toluidine in the copolymers, but the solubility greatly improved (up to 3.83 g/L in N,N‐dimethylformamide), and the conductivity was as high as approximately 17.4 S cm^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1539–1543, 2005     

CdS纳米管合成方法研究进展

作为一种典型的光电半导体材料,硫化镉(CdS)一维纳米材料的合成近年来受到人们的广泛关注.本文综述了阳极氧化铝(AAO)、聚四氟乙烯(PTFE)硬模板,聚乙烯醇(PVA)软模板和超声化学法合成一维CdS纳米管,介绍了各种合成方法中CdS纳米管的形成机制.     

The use of PEEK nanorod arrays for the fabrication of nanoporous surfaces under high temperature: SiN(x) example

Large area silicon nitride (SiN(x)) nanoporous surfaces are fabricated using poly(ether-ether-ketone) (PEEK) nanorod arrays as a template. The procedure involves manipulation of nanoporous anodic aluminum oxide (AAO) templates in order to form an ordered array of PEEK nanopillars with high temperature resistant characteristics. In this context, self-ordered AAO templates are infiltrated with PEEK melts via the "precursor film" method. Once the melts have been crystallized in the porous structure of AAO, the basis alumina layer is removed, yielding an ordered array of PEEK nanopillars. The resulting structure is a high temperature and chemical resistant polymeric nanomold, which can be utilized in the synthesis of nanoporous materials under aggressive conditions. Such conditions are high temperatures (up to 320 °C), vacuum, or extreme pH. For example, SiN(x) nanopore arrays have been grown by plasma enhanced chemical vapor deposition at 300 °C, which can be of interest as mold for nanoimprint lithography, due to its hardness and low surface energy. The SiN(x) nanopore array portrays the same characteristics as the original AAO template: 120 nm diameter pores and an interpore distance of 430 nm. Furthermore, the aspect ratio of the SiN(x) nanopores can be tuned by selecting an AAO template with appropriate conditions. The use of PEEK as a nanotemplate extends the applicability of polymeric nanopatterns into a temperature regime up to now not accessible and opens up the simple fabrication of novel nanoporous inorganic surfaces.     

Effects of anodization and electrodeposition conditions on the growth of copper and cobalt nanostructures in aluminum oxide films

Anodic aluminum oxide (AAO) films were prepared by alternative current (ac) oxidation in sulfuric acid and phosphoric acid solution. The porous structure of the AAO templates was probed by ac electrodeposition of copper. AAO templates grown using an applied square waveform signal in cold sulfuric acid solution exhibit a greater pore density and a more homogeneous barrier layer. UV–vis–NIR reflectance spectra of the Cu/AAO assemblies exhibit a plasmon absorption peak centered at 580 nm, consistent with the formation of Cu nanostructures slightly larger than 10 nm in diameter. Spectroscopic data also indicate that there is little or no oxide layer surrounding the Cu nanostructures grown by ac electrodeposition. The effect of pH of the cobalt plating solution on the magnetic properties of the Co/AAO assemblies was also investigated. Co nanowire arrays electrodeposited at pH 5.5 in H₂SO₄-grown AAO templates exhibit a fair coercivity of 1325 Oe, a magnetization squarness of about 72%, and a significant effective anisotropy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Preparation of highly ordered ZnO nanowire arrays by paired-cell deposition

Highly ordered ZnO nanowire arrays were fabricated by paired cell method into nanoporous anodic alumina oxide (AAO) template. ZnO nanowires were uniformly assembled into the ordered channels of the AAO template. TEM and selected-area electron diffraction patterns indicated that the ZnO nanowires grow as a single crystal. The factors influencing the final filled density of ZnO nanowires, including the solution concentration and the diffusing temperature are discussed briefly. In addition, the possible mechanism is also proposed to account for the growth of the ZnO nanowires in the AAO template. This result has established that this paired cell method makes it possible to grow single-crystalline ZnO nanowires in the AAO template under appropriate conditions.