γ-Irradiation Route to Semiconductor/Polymer Nanocable Fabrication

Abstract

Special attention has been paid to nanotubes and nanowires due to their interesting properties and potential applications. Since the discovery of carbon nanotubes [1] various nanotubes such as WS 2 , MoS 2 , BN, BC 2 N, and semiconductor nanowires such as CdTe and ZnCdSe have been synthesized. [2±7] The template technique is an important method of nanowire fabrication. Usually, there are two types of template: ªtrack-etchº polymer membranes, such as the polycarbonate membrane with 60 nm diameter pores, and the porous aluminum oxide membrane, with a pore diameter of 70 nm. [8,9] However, the challenges of fabricating semiconductor nanowires with a quantum confinement effect are great because technically useful quantum wires will require lateral dimensions less than 10 nm, and it is difficult to fabricate quantum wires on a scale lower than 10 nm. [10] Nanocables with a wire/sheath structure are another kind of potentially useful one-dimensional nanostructure. There have been a few reports on the preparation of semiconductor/insulator nanocables. For example, Si/SiO 2 nanocable has been prepared by combining laser-ablation cluster formation with vapor±liquid±solid (VLS) growth, [11] and b-SiC/SiO 2 nanocable has been obtained by the carbothermal reduction of sol±gel derived silica xerogels containing carbon nanoparticles at 1650 C. [12] In both cases, the outer layers of SiO 2 in nanocables are induced by the reaction atmosphere.In this communication, we design a new strategy for synthesizing a semiconductor/polymer nanocable in a heterogeneous solution system. In this system, an organic monomer with polar groups can self-organize into amphiphilic supramolecules, utilizing the difference in solubility of different fragments in the monomer molecule. Such supramolecules can polymerize to a pre-organized polymer tubule with a hydrophilic core and a hydrophobic sheath. Then the polymer tubule acts as both template and nanoreactor for the following growth of inorganic semiconductor nanowires in the hydrophilic cores from various water-soluble sources. Thus, a nanocable with semiconductor wire in a polymer sheath can be obtained. In this approach, g-irradiation offers an ideal means by which the supramolecules can be polymerized and the tubular structure can be solidified with the desired diameter at room temperature under ambient pressure.Based on the above strategy, a CdSe/poly(vinyl acetate) (PVAc) nanocable with a 6 nm core and an 80 nm diameter sheath was successfully synthesized from a heterogeneous system of vinyl acetate (VAc) monomer, cadmium sulfate (CdSO 4 ×8/3H 2 O), and sodium selenosulfate (Na 2 Se-SO 3 ) under g-irradiation at room temperature and ambient pressure. Appropriate amounts of analytically pure CdSO 4 [8/3H 2 O, Na 2 SeSO 3 , and isopropanol were dissolved in distilled water in a ground-glass stoppered flask, then mixed with VAc. Sodium selenosulfate can be synthesized by refluxing selenium powders in a sodium sulfite (Na 2 SO 3 ) solution according to the literature. [13] Isopropanol was used...

Synthesis and chemical etching of Te/C nanocables

“…Nanocables reveal some fancy performances for their core-shell structure, so they can be used as the connection wires among high-density integrated elements, super capacitor, micro-implements and elements of microrobot. A number of approaches, such as thermal evaporation, γ -irradiation, and templating, have been developed * Author for correspondence (daqingcgs@163.com) to fabricate these kinds of 1-D nanocomposites (Xie et al 1999;Hu et al 2003;Jiang et al 2003). Iijima and his coworkers prepared coaxial three-layer nanostructures consisting of silicon carbide cores via a laser ablation route (Zhang et al 1997).…”

Alignment of Colloidal CdS Nanowires Embedded in Polymer Nanofibers by Electrospinning

“…[12] Semiconductor/polymer cables were produced by the formation of hol-lowed polyvinylacetate polymer tubes, with hydrophilic inner surfaces that permit the formation of inorganic CdSe wires. [13] There have been several attempts to prepare free-standing QWs. Duan and Lieber [14] developed laser-assisted catalytic growth of GaAs QWs.…”

Preparation of Novel Metallic and Bimetallic Cross‐Linked Poly(vinyl alcohol) Nanocomposites under Microwave Irradiation

“…Then, they deposit onto the pre‐nanoparticles of the first‐reduced metal to generate core‐shell‐structured bimetallic nanoparticles. It is well known that PVA chains become cross‐linked after treatment at an elevated temperature (≈250 °C)35 and recently, PVA‐cross‐linked Cu was prepared via hydrothermal treatment at 200 °C for 72 h 14. However, in the present process, PVA cross‐linking with Pt, In and Cu metal ions under microwave irradiation occurs at a relatively low temperature (100 °C).…”