Nanomaterials and Nanocomposites

Zero- to Three-Dimensional Materials and Their Composites

Visakh P. M., María José Martínez Morlanes

• Publisher: Wiley-VCH
• Year: 2016
• Print ISBN: 9783527337804
• eBook ISBN: 9783527683765
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Nanomaterials are defined as materials in which at least one length dimension is below 100 nanometers. In this size regime, these materials exhibit particular - and tunable - optical, electrical or mechanical properties that are not present at the macro-scale. This opens up the possibility for a plethora of applications at the interface of materials, chemistry, physics and biology, many of which have already entered the commercial realm. When nanomaterials are blended with other materials not necessarily in the nanometer regime, the resulting nanocomposites can exhibit dramatically different properties than the bulk material alone, leading to an enhanced performance in terms of, for example, increased thermal and mechanical stability.

This book presents the synthesis, characterization and applications of nanomaterials and nanocomposites, covering zero-dimensional, elemental nanoparticles, one-dimensional materials such as nanorods and nanowhiskers, two-dimensional materials such as graphene and boron nitride as well as three-dimensional materials such as fullerenes, polyhedral oligomers and zeolites, complemented by bio-based nanomaterials, e.g., cellulose, chitin, starch  and proteins. Introductory chapters on the state-of-the-art of nanomaterial research and the chemistry and physics in nanoscience and nanotechnology round off the book.

Chapter 1
Introduction for Nanomaterials and Nanocomposites: State of Art, New Challenges, and Opportunities

P. M. Visakh

1.1 Chemistry of Nanoscience and Technology

Science uses methodologies from synthetic chemistry and materials chemistry to obtain nanomaterials in specific sizes and shapes, with specific surface properties, defects, and self-assembly properties, designed to accomplish specific functions and uses [1]. Nanoscale is usually defined as being smaller than 1/10th of a micrometer in at least one dimension; this term is also used for materials smaller than 1 µm. An important aspect of nanomaterials is the vast increase in the surface area to volume ratio, which incorporates the possibilities of new quantum mechanical effects in such materials. Suspensions of nanoparticles are possible because the interaction of the particle surface with the solvent molecules is strong enough to overcome differences in density, which usually results from a material either sinking or floating in a liquid. Nanoparticles often have unexpected visual properties because they are small enough to confine their electrons and produce quantum effects. Nanostructured materials are classified as zero-dimensional, one-dimensional, two-dimensional, three-dimensional nanostructures. Nanomaterials are materials that are characterized by an ultrafine grain size (<50 nm) or by a dimensionality that is limited to 50 nm. Nanomaterials can be created with various modulation dimensionalities as defined by Richard W. Siegel: zero (atomic clusters, filaments, and cluster assemblies), one (multilayers), two (ultrafine-grained overlayers or buried layers), and three (nanophase materials consisting of equiaxed nanometer-sized grains). Recently, researchers are using a modified CVD technique for the fabrication of 0D Nanostructured materials (NSMs) [2, 3].

Palgrave and Parkin [4] used the aerosol-assisted CVD technique to fabricate the Au nanoparticles on a glass substrate. Toluene is used as a precursor to deposit gold nanoparticles onto glass. The sizes of Au nanoparticles are 100 nm. Boyd et al. [5] developed a new CVD process that can be used to selectively deposit materials of many different types. In this technique, they used the Plasmon resonance in nanoscale structures to create the local heating, which is crucial in order to initiate deposition when illuminated by a focused low-power laser [6]. Elihn et al. [7] synthesized the iron nanoparticles enclosed in carbon shells by laser-assisted chemical vapor decomposition (LCVD) of ferrocene (Fe(C₅H₅)₂) vapor in the presence of the Ar gas. One-dimensional nanomaterials have nanoscale sizes along two-dimensions and a rod-like or wire-like appearance. In such nanomaterials, quantum confinement and surface area-related nanoscale effects are more pronounced compared to 2D nanomaterials. Lyotropic liquid crystal (LLC) template-assisted synthesis is one of the most facile and most applied methods for the synthesis of 1D NSMs such as nanowires, nanorods, nanotubes, nanobelts, nanoribbons, and nanospindles [8–12]. Kijima et al. [12] fabricated the platinum, palladium, and silver nanotubes, with inner diameters of 3–4 nm and outer diameters of 6–7 nm, by the reduction of metal salts confined to lyotropic mixed Liquid Crystals (LCs) of two different sized surfactants.

Electrodeposition processes have a wide range of advantages such as low cost, low energy consumption, high growth rate at relatively low temperatures, being environmentally friendly, and having good control of the deposition thickness, shape, and size. Xia et al. [13] fabricated the MnO₂ nanotube and nanowire arrays via an electrochemical deposition technique using porous alumina templates. Tang et al. [14] prepared the Si nanowires on Si substrates by the hydrothermal deposition route under low temperature and pressure. The obtained Si nanowire consists of a polycrystalline Si core and an amorphous silica sheath. The diameter and length of Si nanowires were 170 nm and 10 lm, respectively. The essence of nanoscience and nanotechnology is the creation and use of molecules, molecular assemblies, materials, and devices in the range of 1–100 nm, and the exploitation of the unique properties and phenomena of matter at this dimensional scale.

1.2 Carbon Nanotubes and Their Nanocomposites

Carbon nanotubes CNTs consist of tubes formed by rolled sheets of graphene (one atomic layer of graphite). The tubes are arranged in a concentric manner to form single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs) and multi-walled carbon nanotubes (MWCNTs). CNTs are excellent candidates for use in various applications: as biological and chemical sensors, as probe tips for scanning probe microscopy, in nano-electromechanical systems (NEMS), and as reinforcement in nanocomposites [15, 16]. CNTs consist of rolled graphene sheets arranged in a concentric manner and are classified according to the number of walls. The length of the nanotubes is between a few hundred nanometers and a few micrometers. Due to their length they become entangled. In general, the SWCNTs are defect-free, whereas MWCNTs present defects. An individual graphene sheet has high strength (130 GPa) and high electrical and thermal conductivities [17, 18]. Due to these remarkable properties, it is expected that since the CNTs consist of rolled graphene sheets, they will also exhibit extraordinary properties. CNTs have generated a great deal of interest in recent years.

The application of CNTs as a reinforcement is very important in any kind of matrix, but is more widely used in polymer matrix composites. The conventional polymer matrix composites have found application in a wide range of fields due to properties such as low density, reasonable strength, flexibility, and easy processability. However, the search for materials capable of improving the performance of advanced components has triggered the study and production of CNTs reinforced nanocomposites. CNTs/epoxy nanocomposites have been extensively investigated due to their industrial and technological applications. These nanocomposites are fabricated using melt mixing or solution mixing methods. Zhou et al. [19] demonstrated that it is possible to improve the strength and fracture toughness with the incorporation of 0.3 wt% CNTs in the epoxy matrix. Velasco-Santos et al. [20] studied the CNTs/PMMA (poly Methyl Methacrylate Monomer) nanocomposites and observed an increase in the storage modulus of 1135% for composites, with 1 wt% of CNTs dispersed using an in situ polymerization at 90 °C.

Ceramic matrices reinforced with CNTs can provide nanocomposites with super plastic deformability, high strength, improved fracture toughness, and higher electrical and thermal conductivities, while metallic matrices reinforced with CNTs are expected to produce nanocomposites of high strength and specific stiffness, which is a desirable coefficient of thermal expansion and good damping properties [21]. Yamamoto and Hashida [22] developed a new technique to obtain a more homogeneous dispersion of CNTs and improve the bonding to the alumina matrix. This treatment involved the use of a precursor method for the synthesis of an alumina matrix, MWCNTs modified by a covalent functionalization (by a concentrate H₂SO₄ and HNO₃ acid mixture), and the Spark Plasma Sintering (SPS) method. Nguyen et al. [23] showed that it is possible to produce ultrafine-grained MWCNT/Ni composites by the SPS method with 97% of density. The authors used modified CNTs by noncovalent functionalization to improve the cohesion between the CNT and Ni powders. The composites revealed a higher value of hardness in the CNT than the Ni. Kwon and Leparoux [24] obtained a higher strength for CNT/Al nanocomposites produced by mechanical ball milling followed by a direct...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• List of Contributors
• Chapter 1: Introduction for Nanomaterials and Nanocomposites: State of Art, New Challenges, and Opportunities
• Chapter 2: Chemistry of Nanoscience and Technology
• Chapter 3: Carbon Nanotubes and Their Nanocomposites
• Chapter 4: Graphene and Graphene Sheets Based Nanocomposites
• Chapter 5: Nanocomposites of Polyhedral Oligomeric Silsesquioxane (POSS) and Their Applications
• Chapter 6: Zeolites and Composites
• Chapter 7: Mesoporous Materials and Their Nanocomposites
• Chapter 8: Bio-based Nanomaterials and Their Bionanocomposites
• Chapter 9: Metal-Organic Frameworks (MOFs) and Its Composites
• Chapter 10: Modeling Methods for Modulus of Polymer/Carbon nanotube (CNT) Nanocomposites
• Chapter 11: Nanocomposites Based on Cellulose, Hemicelluloses, and Lignin
• Index
• End User License Agreement