Nanotubes template-free preparation

Figure 2.18 Typical (a) SEM and (b) TEM of PANI-NTs prepared by dopant-free template-free method. (Reprinted with permission from Macromolecular Chemistry and Physics, Formation mechanism of polyaniline nanotubes by a simplified template-free method by H. Ding,]. Shen, M. Wan andZ. Chen, 209, 8, 864-871. Copyright (2008) Wiley-VCH)...

Conductive polymeric nanostructures can be prepared by using hard or soft templates or with template-free methods. The template method has been extensively used because of its simplicity, versatility and controllability. Some further features on this topic are reported in Section 1.3. A typical hard template material can be a thin porous film of aluminum oxide or polycarbonate and polymeric materials ean be deposited into the pores to form nanotubes or nanowires. The electrochemical template method enables a better control of the dimensions compared with the chemical methods. In addition, the nanostructures produced by the electrochemical method are in solid contact with a base electrode that is beneficial for further processing steps when building an electrochemical device. 

In addition to spherical particle nanocomposites, the preparation of nanotubes and nanowires composites with both magnetic and electrical properties is of great interest due to the enhancement of the conductivity. In general, the room temperature conductivity increases when the diameter decreases [79]. Conducting polymer nanotubes can be chemically or electrochemically synthesized by hard and soft template or template-free method in the presence of magnetic nanoparticles [8, 23, 27]. 

All products were used as received without any modification or purification, unless stated otherwise. Ultrapure milli-Q water was used to prepare the 4.10" M rhodamine 6G solution. Trititanate nanotubes (TNT) were prepared using a template free, hydrothermal synthesis method identical to the one described by S. Ribbens et al [2]. Mesoporous titania was synthesized using the Evaporation Induced Self-Assembly method (EISA) followed by a post modification in ammonia to stabilize the stracture. The surfactant was removed by calcination at 450°C [3]. 

A templating approach can be important for preparing low-dimensional platinum nanostructures, as the platinum metal has a fee cubic symmetry. In template-free solution-phase synthesis, the introduction of defects can serve as a useful strategy. Some examples of nanorods, nanowires and nanotubes of platinum prepared using different methods, with and without templates, are shown in Figure 10.8. Notably, when the diameter of nanowires becomes very small, they can exhibit excellent flexibUity and form interconnected networks. 

Xi D, Pei Q (2007) In situ preparation of free-standing nanoporous alumina template for polybithiophene nanotube arrays with a concourse base. Nanotechnology 18 095602... 

Highly anisotropic ID nanostructures composed of closely packed nanoparticles have been prepared using linear macromolecular or supramolecular templates such as polyelectrolytes [2, 3], carbon nanotubes [2-5], DNA [6-9], peptide nanofibrils [10, 11], tubulin [12, 13] and bacteriophage and tobacco mosaic virus rods [14, 15]. Moreover, ID arrays are produced by spontaneous alignment of nanoparticles with intrinsic electric dipoles to form anisotropic chains of metallic nanoparticles, driven by heterogeneities in the surface chemistry and polarity of the nanoparticles [16]. These methods have been recently used to obtain defined nanostructures, predominantly in many steps and not defect free, with inhomogeneous metallic nanoparticle distribution. 

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