Types of Nanomaterials

A composite is a material that combines one or more separate components. Composites are designed to exhibit the best properties of each component. A large variety of systems combining one, two and three dimensional materials with amorphous materials mixed at the nanometer scale [18]. 

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The photoluminescence of these nanoparticles has very different causes, depending on the type of nanomaterial semiconductor QDs luminescence by recombination of excitons, rare-earth doped nanoparticles photoluminescence by atom orbital (AO) transitions within the rare-earth ions acting as luminescent centers, and metallic nanoparticles emit light by various mechanisms. Consequently, the optical properties of luminescent nanoparticles can be very different, depending on the material they consist of. 

The Stober method can be used to form core-shell silica nanoparticles when a presynthesized core is suspended in a water-alcohol mixture. The core can be a silica nanoparticle or other types of nanomaterials [46, 47]. If the core is a silica nanoparticle, before adding silicon alkoxide precursors, the hydroxysilicates hydrolyzed from precursors condense by the hydroxide groups on the surface of the silica cores to form additional layers. If the core is a colloid, surface modification of the core might be necessary. For example, a gold colloid core was modified by poly (vinylpyrrolidone) prior to a silica layer coating [46]. 

It was found that for different pressures of different gases and different types of nanomaterials, there were different responses in the shifts of the probe signal for each cycle of gassing and degassing of the cavity. This preliminary work suggests... 

Definition of the nanoscale covers all species having at least one diameter of 100 nm or less. When nanoparticles are intentionally synthesized to be used in a range of consumer goods, they are called nanomaterials. Without doubt, one can say that we are now at the beginning of nanoindustrial revolution. Different types of nanomaterials are frequently applied in electronics, space technology, cosmetics and sunscreens production, medicine and pharmacy, solar energetics, textile industry, sport equipment, and many other areas [22, 23]. 

The material in a nanoscale dimension provides an important surface to volume ratio. The change in the surface energy induces the atomic distances of the surface atoms to be contracted. As a result, in this type of nanomaterials, large disorder and higher catalytic activity can be expected [22], The former phenomenon is clearly observed in the X-ray diagram which delivers broader diffraction peaks [1, 6, 13, 22]. 

A. Govindaraj obtained his PhD degree from University of Mysore and is a Senior Scientific Officer at the Indian Institute of Science, and Honorary Faculty Fellow at the Jawaharlal Nehru Centre for Advanced Scientific Research. He works on different types of nanomaterials. He has authored more than 100 research papers and co-authored a book on nanotubes and nanowires. 

Types of Nanomaterials Characteristics Applications in Pharmacy References... 

Types of Nanomaterials Materials Involved2 Manufacturing Methods... 

Types of Nanomaterials Materials Involved0 Manufacturing Methods References... 

Single-wall carbon nanotubes are new types of nanomaterial, the study of which generates about five research papers [234] from around the world, each day. An important feature of these structures is that the aromatic rings of the folded graphite sheet that constitutes the tube, are no longer planar. This feature represents a new challenge for accepted theories of 7r-bonding. 

In recent years, we have seen an explosive interest in nanomaterials, in particular in nanofibers, nanofilaments, and nanotubes of the very different chemical composition. The interest arises from the specific mechanical and physicochemical properties of these nano objects, which allow them to be used, for example, as specific adsorbents, catalyst supports, reinforcing components of composite materials, and so on. The most cited generic types of nanomaterials are carbon nanofilaments and nanotubes. Numerous methods for preparing these carbon materials are known. However, the simplest method seems to be thermal pyrolysis of various carbon contain ing precursors (e.g., carbon monoxide, saturated and unsaturated hydro carbons, etc.) in the presence of special catalysts that are typically nanosized particles of nickel, cobalt, iron metals, or their alloys with different metals. 

The introduction of a new architecture such as nanomaterials necessitates the need for new terminology and methods of classification and characterization. We must also understand the mechanisms by which individual nanostructures may assemble into larger materials, as this will greatly affect the properties of the bulk device for a particular application. This chapter will focus on all of these important issues, with an introduction to the various types of nanomaterials, laboratory techniques used for their synthesis, and (perhaps most importantly) their role in current/future applications. 

It is clear that the cathode immersion depth, as well as the current, play important roles in controlling the type of nanomaterial formed. The experimental... 

Interest in investigations of low-dimension systems is concerned with both new fundamental problems and perspectives of creation of new systems with wide functional capabilities for nanoelectronics, measuring equipment, communication facilities, etc. Nanostructural metal films are important type of nanomaterials [1,2]. Basic properties of the films can be modified by dopants [3]. The structure depends substantially on the dopant nature and content [4]. In this work, structural features and physicomechanical properties of nickel films with different boron content were studied. 

LSPR absorption bands are characteristic of the type of nanomaterial, the diameter of nanoparticles, and their distribution (Freeman et al., 1995 Nath and Chilkoti, 2002). LSPR can detect an immediate change in the interfacial refractive index (RI) of the surrounding medium (Mock et al., 2003 Raschke et al., 2003 Nath and Chilkoti, 2004), which is greatly affected by the attachment of biomolecules at the colloid-solution interface (Himmelhaus and Takei, 2000 Mock et al., 2003 Raschke et al., 2003 Nath and Chilkoti, 2004 Endo et al.,... 

Due to the certainty that nanomaterials will be exposed to the environment, it is imperative to understand the subsequent fate, transport and transformation that will determine their impact on the environment. A model of the movement of nanoparticles through the air, soil, and water is shown in Figure 21.7 (11). The size-dependent properties of nanomaterials can influence how they will be transported and transformed in the environment therefore, the behavior of larger-sized materials cannot be used to predict nanomaterial behavior. The type of nanomaterial exposed and the medium it enters are important factors for determining the fate and toxicity of the nanomaterial. These factors will also be important when considering measures for exposure control, waste treatment, or removal of nanomaterials from the environment or biological systems. 

This section will consider in greater detail specific examples of particular types of nanomaterials interacting with different media in the environment. The fate and transport of carbon-based nanomaterials, including carbon nanotubes and fuUerenes, in aqueous environments and the properties of commercial oxide nanoparticles that affect their removal in water will be discussed. Nanomaterial exposure to soils and porous media, focusing on transport and retention, as well as environmental interactions of cadmium selenide (CdSe) quantum dots with biofilms will be presented. These specific examples provide an idea of the types of environmental interactions that must be considered, and illustrate that environmental impacts of nanomaterials cannot be generalized, but rather, are dependent on properties of the material in question and the environment to which it is exposed or transported. 

In the nanotechnology field, carbon-based materials and associated composites have received special attention both for fundamental and applicative research. In the first kind, carbon compounds may be included, often taking the form of a hollow spheres, ellipsoids, or mbes. Spherical and ellipsoidal carbon nanomaterials are referred to as fullerenes, while cylindrical ones are called nanombes and nanofibers. In the second class, one includes composite materials that combine carbon nanoparticles with other nanoparticles, or nanoparticles with large bulk-type materials. The unique properties of these various types of nanomaterials provide novel electrical, catalytic, magnetic, mechanical, thermal, and other features that are desirable for applications in commercial, medical, military, and enviromnental sectors. This is the case for conducting polymers (CPs) and carbon nanombes (CNTs) [1-5]. 

Among various types of nanomaterials, metal nanoparticles, especially silver nanoparticles, have great importance. Antimicrobial activity is the main feature determining the popularity of this nanometal. Sources of specialized scientific literature provide many reports on its preparation, properties, and applications in these fields of science or industry where aseptic and antiseptic effects are particularly desirable (medicine, nursing, cosmetology, optics, bioengineering, botany, construction industry, textile, and food industries) (Jung et al., 2008). 

Three different types of nanomaterials, based on their dimensional characteristics, are generally used to prepare polymer nanocomposites. These include nanomaterials with only one dimension in the nanometre range (e.g. nano-clay), those with two dimensions in the nanometre scale (e.g. carbon nanotubes) and those that have all three dimensions in the nanometre scale (e.g. spherical silver nanoparticles), as stated earlier. Thus nanosize thin layered aluminosilicates or nanoclays, layer double hydroxide (LDH), a large number of nanoparticles of metals and their oxides, carbon nanotubes and cellulose nanofibres are used as nanomaterials in the preparation of vegetable oil-based polymer nanocomposites. 

Recently, the emerging need for high-speed electronics and renewable energy has motivated researchers to discover, develop and assemble new types of nanomaterials. Among the different carbon allotropes, graphene... 

The process involves a gas-phase chemical reaction in which a solid material is deposited on the substrate. Nanostructure ceramics and composites are the most common types of nanomaterials produced by CVD, which uses carrier gas vapors on the substrate to keep the metal ion at the zero valent state and then depositing it on a hot-wall reactor to form a solid material on cooling. It is a relatively slow process with a good control over the chemical composition and size, along with a large area of flexibility and relatively low reproducibility. 

The cytotoxicity of nanoparticles depends on the applied cell line. The same type of nanomaterial can have a different cytotoxic effect for different cell lines. The size of the nanoparticles influences not only the cytotoxicity of the material, but also the possibility of the particles penetration inside the cell. The smaller the nanopaiticle can easier and faster to penetrate into the cell (nucleus) and determine the lower cytotoxicity. Both the antibacterial and the cytotoxic properties of nanosilver depend on the amount, size and shape of the applied nanoparticles and the amount of the released silver ions. 

All types of nanomaterials exhibits type IV isotherm, with pore size less than 20 A. The inflection point depends on the pore size and sharpness. The BET surface area and the total pore volume at relative pressure (P/P ) = 0.953 for the calcined materials which depends on the concentration of the template used along with temperature and the reaction conditions during the synthesis of nanomaterials. 

A review of the wastewater treatment literature suggests a number of research needs. Efforts to characterize alumina, ceria, and silica particles in both waste materials and natural water systems face difficult metrology challenges. There is a need for vahdated methodologies that can discriminate quantitatively between individual types of nanomaterials and evaluate concentration by size, number count, and mass concentration within real environmental matrices. The few published evaluations of alumina, ceria, and silica nanoparticle removal in wastewater treatment processes have primarily addressed removal in municipal-type biological wastewater treatment processes whereas relatively little information is available regarding alumina, ceria, and silica nanoparticle removal in the types of physicochemical treatment processes that are often used by fabs to pretreat wastewaters prior to discharge. 

As described elsewhere in this volume, self-assembly is a versatile synthetic strategy to form many different types of nanomaterials. It is therefore worth considering what is special about gel-phase materials and what potential applications may stem from these unique features. ... 

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