Xiaoru Li

Synthesis and Growth Mechanism of Ni Nanotubes and Nanowires

Highly ordered Ni nanotube and nanowire arrays were fabricated via electrodeposition. The Ni microstructures and the process of the formation were investigated using conventional and high-resolution transmission electron microscope. Herein, we demonstrated the systematic fabrication of Ni nanotube and nanowire arrays and proposed an original growth mechanism. With the different deposition time, nanotubes or nanowires can be obtained. Tubular nanostructures can be obtained at short time, while nanowires take longer time to form. This formation mechanism is applicable to design and synthesize other metal nanostructures and even compound nanostuctures via template-based electrodeposition.

Fabrication of Patterned Polystyrene Nanotube Arrays in an Anodic Aluminum Oxide Template by Photolithography and the Multiwetting Mechanism

Patterned polystyrene (PS) nanotube arrays were successfully fabricated using photolithography via the polymer solution-wetting method. The microstructure of these nanotubes was investigated using conventional and high-resolution transmission electron microscopy (HRTEM). Two major types of morphology were observed for these PS nanotubes, one being bamboo-like and the other being barrel-shaped. The multiwetting mechanism was proposed to explain the different morphologies. X-ray diffraction (XRD) showed that the PS nanotubes have a higher degree of crystallinity than bulk PS. In addition, crystalline lattice fringes were observed in some regions of the PS nanotubes using HRTEM. Patterned polymer nanotube arrays could be used for nanocable coating to protect from oxidation and corrosion in nanodevices.

Synthesis and Functions of Ag2S Nanostructures

The paper presents a review about synthesis and applications of Ag2S nanostructures. As the modern photoelectric and biological materials, Ag2S nanomaterials are potentially useful for both structure and function purposes. Ag2S is a direction narrow band gap semiconductor with special properties. Ag2S nanostructures have been widely researched in chemistry and biochemistry fields because of their unusual optical, electrical, and mechanical properties. It can also be used in many fields, such as photovoltaic cells and infrared detector. In the past few years, Ag2S nanostructures have been synthesized by various methods. The article mainly discusses the four types of preparation methods. Moreover, this article shows a detailed review on the new properties, fabrication, and applications of Ag2S nanocrystals.

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.

Assembly of one-dimensional polymer nanostructure arrays by photolithographic approaches

In this work, large area polymer nanostructure arrays with different patterns were successfully obtained by photolithographic approach and wetting anodic aluminum oxide (AAO) templates. First of all, the AAO templates with patterns were produced by photolithographic approach. Then the AAO/pattern membrane was used as a secondary template to fabricate polymer nanostructure arrays by solution-wetting and melt-wetting methods. The morphology of the polymer nanostructures has been characterized using scanning electron microscopy and transmission electron microscopy. The different factors have been discussed in the process of experiments.

Effect of Each Layer on Anisotropic Magnetic Properties of Nd/Fe/Polyamide 66 Three-Layer Coaxial Nanocables

One-dimensional (1D) Nd/Fe/polyamide 66 (Nd/Fe/PA66) three-layer coaxial nanocable arrays with high aspect ratio and highly anisotropic magnetization were successfully prepared via layer-by-layer deposition in the anodic aluminum oxide template. The morphology, chemical composition, and magnetic properties of Nd/Fe/PA66 nanocables were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and vibrating sample magnetometry . The effects of 1D nanocables on the magnetic properties of the assembled ordered arrays have been systematically investigated. The structural properties of these nanostructures are investigated as a function of the geometrical parameters. The magnetic anisotropy of Nd/Fe/PA66 nanocables has been significantly enhanced owing to the doped Nd that possesses a larger spin-orbital coupling and leads to a synergistic effect with Fe to enhance anisotropy energy.

Application of high-resolution transmission electron microscopy and electron energy-loss spectroscopy in the characterization of polymer nanotubes

Abstract Polyamide 6 (PA6) and polystyrene (PS) nanotubes were successfully fabricated by polymer solution-wetting method. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and electron energy-loss spectroscopy (EELS) techniques were employed to investigate their crystallization phenomena. It has been found in HRTEM images that the crystalline lattice fringes are observed in some regions of the nanotube walls. XRD analysis showed that these two kinds of polymer nanotubes have a higher degree of crystallinity than that of the bulk materials. PA6 nanotubes dominate in γ phase while bulk PA6 present mainly in α phase. EELS has been used to determine the ratio of C=C and C-C in PS nanotubes, and our result is consistent with the theoretical calculation. HRTEM and EELS will shed light on the microstructural characterization of polymer nanotubes.

Preparation and Magnetic Properties of Nd/FM (FM=Fe, Co, Ni)/PA66 Three-Layer Coaxial Nanocables

A new preparation method of three-layer coaxial nanocables has been developed in this work. Nd/FM (FM=Fe, Co, Ni)/PA66 three-layer coaxial nanocables were assembled successfully from outer to inner layer by layer. PA66 nanotubes which served as the outer shell were prepared by polymer solution wetting AAO template. Ferromagnetic metals and Nd were deposited into pre-prepared PA66 nanotubes to be served as the middle layer and inner core, respectively. The results show that the structure has effects on the magnetic properties, and the nanocable preparation allows each layer, length, and thickness of the nanocables to be tuned.

Covalent grafting of triazine derivatives onto graphene oxide for preparation of epoxy composites with improved interfacial and mechanical properties

Interface interactions are the important problems in improving the mechanical properties of graphene and polymer composites. In this work, a simple method is proposed to prepare epoxy composites with admirable properties through constructing dendrimers with cyanuric chloride (TCT) and diethylenetriamine (DETA) onto graphene oxide (GO) surface. The FTIR, XRD, XPS, Raman spectroscopy, SEM and TEM were used to confirm the successful grafting of TCT and DETA molecules onto the surface of GO. The interfacial adhesion between GO–TCT–DETA and epoxy resin is enhanced due to the formation of a strong chemical bond between the amino group on the GO surface and the epoxy resins. The tensile and flexural strength of GO–TCT–DETA/epoxy composites have considerable improvement (40.79 and 48.56%) compared with that of epoxy resin due to stronger interfacial interaction. In addition, the strengthening mechanism and dispersion of GO–TCT–DETA in epoxy matrix were also demonstrated.