Mônica Jung de Andrade

Thin, conductive, carbon nanotube networks over transparent substrates by electrophoretic deposition

A new method was developed for deposition of carbon nanotube networks (CNTNs) over transparent and electrically non-conductive substrates. This method allows the deposition of functionalized or surfactant-stabilized carbon nanotubes dispersed in water. The nanotube films can be applied over complex geometries, on non-conductive rigid or flexible substrates and over large areas in a continuous manner. The carbon nanotube films are deposited by electrophoretic deposition (EPD) using a thin film layer of conductive metal, such as aluminium or titanium. The metal layer oxidizes during the EPD, becoming transparent. The carbon nanotube films can be easily patterned using this technique.

Nanostructured materials for engineering applications

1 INTRODUCTION 2 NANOMATERIALS PROPERTIES 3 NANOMAGNETIC MATERIALS 4 OPTOELECTRONIC AND FERROELECTRIC APPLICATIONS 5 NANOSTRUCTURED MATERIALS FOR ENERGY APPLICATIONS 6 MATERIALS FOR BIO-APPLICATIONS 7 NANOMATERIALS AND CATALYSIS 8 NANOREINFORCEMENTS FOR NANOCOMPOSITE MATERIALS 9 NANOMATERIALS FOR APPLICATIONS IN REFRACTORY MATERIAIS 10 MATERIALS FOR ADSORBENT APPLICATIONS 11 USE OF NATURAL AND MODIFIED NATURAL NANOSTRUCTURED MATERIALS

Dynamic percolation of carbon nanotubes in liquid medium

In this article we have measured the electrical behaviour of carbon nanotubes (CNTs) suspended in electrically insulating liquid. The concentration dependence of conductivity shows a percolation behaviour similar to that observed in electrical composites with an insulating matrix. The value of the critical percolation concentration is strongly determined by the aspect ratio of the fillers forming the network through dynamic percolation. We characterized several single- and multi-wall carbon nanotube materials by the newly proposed method and received a good correlation with the results obtained by methods commonly used for CNT characterization (Raman spectroscopy, transmission electron microscopy and electrical conductivity of free standing papers). As a comparison, fine graphite material has also been evaluated. The electrical properties of the suspensions can be used as a method for CNT characterization. This method can yield important information for CNT producers and for the selection of electrically conducting structures for composites applications.

Nanoreinforcements for Nanocomposite Materials

The range of materials currently available as fillers for nanocomposites include nanoparticles, nanoplatelets, carbon nanotubes, nanofibers, and, more recently, graphenes or even a combination of these unique materials. Several companies already supply a variety of ceramic, metal and polymer nanocomposite products that reach into many industrial sectors, such as aerospace, energy and sporting goods. Polymer nanocomposites attract most of the research and development effort and, as a result, more traditional microreinforced materials are already being substituted. Indeed, the combination of nanomaterials with thermoplastic or thermoset polymers may lead to very interesting mechanical or physical properties. As shown in this chapter, these nanofillers are slowly finding their way into mainstream commercial use and their even wider application can be foreseen when difficulties regarding cost, homogeneous dispersion and poor adhesion to the host matrix are further minimized.

Use of Natural and Modified Natural Nanostructured Materials

The use of natural nanomaterials is environmentally friendly, socially responsible and cost effective. Hence, several industries are investing in cheap ways to explore and process natural resources to make natural nanomaterials available. Natural nanomaterials are abundant; however, certain drawbacks such as incompatibility and extraction are a challenge to make their use more advantageous. Montmorillonite is the most common natural nanomineral used in industry and nanocellulose could be extracted from the most important skeletal component in plants, cellulose. In this chapter a brief overview is given of natural and modified natural nanostructured materials, with emphasis on layered silicates (clays) and cellulose-based materials, followed by some industrial examples.

Nanostructured Materials for Energy Applications

There is great interest in research related to alternative forms of electricity production in order to promote increased quantity and quality of the energy system, maintaining and enhancing environmental sustainability, economic, emphasizing efficient use of renewable energy resources. In this context, it is important to develop new technologies for energy generation, especially those from renewable resources. Nanostructured materials have been extensively researched in application like lithium ion batteries, supercapacitors, solar cells and fuel cells. This chapter contains a brief overview of some companies that are already dealing with nanostructured materials for lithium ion batteries, supercapacitors, solar cells and fuel cells, followed by recent developments on research of nanostructured materials for elements of Intermediate Temperature Solid Oxide Fuel Cell.

Optoeletronic and Ferroeletric Applications

In this chapter, some of the tendencies in the fields of nanostructured materials for optoeletronic and ferroelectric applications in terms of research and industry are presented. Special emphasis is given to carbon nanotubes, graphene, perovskite, aurivillius and thin films. In the field of nanotechnology applied to ceramic materials, there are different methods of fabrication and processing of these materials, such as powder form, bulk or thin films. The appropriate choice of processing depends on the application desired. The main tendency for both optoeletronic and ferroelectric applications is the use of thin films, which can contribute to the minituarization of devices such as transistors, photovoltaics, liquid crystals, light emitting diodes and sensors. Different techniques can be used to produce these nanometric structures as thin films, including in-situ growth and post-synthesis techniques. The selection of the adequate technique depends on the material and thickness of the film desired, which will have direct effect over the properties.

Chemical resistance of silicate glass-ceramics

ABSTRACT This work is concerned about the chemical characterization of monolithic diopside-based glass ceramics (GCs). Variations from this composition were carried out through the addition of P2O5 to increase crystal density and Al2O3 to optimize the chemical properties of the GCs. The addition of MgO was sufficient for the crystallization of diopside, but additions of P2O5 made the formation of this crystalline phase difficult. The highest volume of diopside crystals was about 76% for the formulation with 5% weight of alumina. As expected, chemical resistance is directly influenced by the composition of the glass ceramic, but not so much by the fraction of crystals volume.