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www.soran.edu.iq Industrial chemistry Kazem.R.Abdollah Nanotechnology Fundamental Principles and Applications 1

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www.soran.edu.iq Research in nanotechnology has seen an explosive growth during the past decade, fueled by significant investment in research and development and the appearance of a cornucopia of consumer-based products. Based on current growth rates, it is estimated that nano-related goods could be in the range of $1 2.5 trillion market by 2015 globally.

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www.soran.edu.iq PrefixSymbol1000 m 10 n Decimal English word [n 1] [n 1] Since [n 2] [n 2] yotta Y 1000 8 10 24 1000000000000000000000000septillion1991 zetta Z 1000 7 10 21 1000000000000000000000sextillion1991 exa E 1000 6 10 18 1000000000000000000quintillion1975 peta P 1000 5 10 15 1000000000000000quadrillion1975 tera T 1000 4 10 12 1000000000000trillion1960 giga G 1000 3 10 9 1000000000billion1960 mega M 1000 2 10 6 1000000million1960 kilo k 1000 1 10 3 1000thousand1795 hecto h 1000 2/3 10 2 100hundred1795 deca da 1000 1/3 10 1 10ten1795 1000 0 10 0 1one deci d 1000 1/3 10 1 0.1tenth1795 centi c 1000 2/3 10 2 0.01hundredth1795 milli m 1000 1 10 3 0.001thousandth1795 micro 1000 2 10 6 0.000001millionth1960 nano n 1000 3 10 9 0.000000001billionth1960 pico p 1000 4 10 12 0.000000000001trillionth1960 femto f 1000 5 10 15 0.000000000000001quadrillionth1964 atto a 1000 6 10 18 0.000000000000000001quintillionth1964 zepto z 1000 7 10 21 0.000000000000000000001sextillionth1991 yocto y 1000 8 10 24 0.000000000000000000000001septillionth1991

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www.soran.edu.iq What Is Nano? The prefix nano literally means one billionth of a meter and one nanometer is thought to be a magical point on the dimensional scale. This is because these are the smallest solid materials that can be fabricated since anything smaller than nanometer would essentially be a small molecule or an atom and not condensed matter. Thus, nanostructures (materials with one dimension in the range between 1 and 100 nm) are the smallest solid things possible to make. To put things in context, ten hydrogen atoms make up one nanometer.

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Nanotechnology Nanotechnology is a broad encompassing area incorporating principles of sciences, engineering and technology to understand, control, manipulate, and construct matter in the 1100 nm dimension range. Thus, one can define nanotechnology to be a technology based on the manipulation of individual atoms and molecules to build complex structures that have unique physical, chemical, and/or biological properties different from bulk properties.

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www.soran.edu.iq Estimates based on key indicators such as publications, patent applications, products, and research and development funding suggest that the average growth in this area has been 2335% since 2000. In 2008 alone, over 15,000 manuscripts in the broad area of nanoscience/nanotechnology have been published, compared with ~5,000 in the year 2000, illustrating robust growth in this fertile area of research.

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www.soran.edu.iq Nanotechnology is a technology that is expected to create products or devices that are lighter, robust, safer, reliable, and durable. At the core of nanotechnology is what is called molecular technology or molecularmanufacturing. Molecular technology refers to manufacturing processes using molecular machinery, i.e., obtaining molecule-by-molecule control of products and by-products via positional chemical synthesis.

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www.soran.edu.iq A New Realm of Matter Chemistry is the study of atoms and molecules whose dimensions are generally less than one nanometer (e.g., a carbon-carbon single bond length is only 0.154 nm), while the majority of physics, particularly the area of condensed matter, and deals with solids that are essentially an infinite array of bound atoms or molecules greater than 100 nm. For example, the melting point of gold (Au) nanoparticle is lower than the melting point of the bulk Au metal and does not necessarily vary linearly with particle size. Also, a nanoscale wire may not necessarily obey Ohms law that is the foundation and cornerstone of the electronics industry. Thus, the nanoscale size imparts unique and often unpredictable physical, chemical, and/or biological properties distinct from the bulk.

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www.soran.edu.iq The field of nanomaterials is not unique to manmade substances; nature has been utilizing nanomaterials for millions of years. Several biological systems contain several nanoscale materials. For example, bones, teeth, and shells are molecular composites of proteins and biominerals that have superior strength and toughness. Human bones contain minerals with particle sizes in the nanoscale regime. Another example is found in certain aquatic bacteria that are able to orient themselves using the Earths magnetic field. This is possible because they contain chains of nanosized, singledomain magnetite (Fe3O4) particles.

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www.soran.edu.iq Synthesis One method, called Solvated Metal Atom Dispersion (SMAD) method, allows the preparation of gram scale and higher quantities of metal nanoparticles such as Au, Ag, Cu, Pd, etc., metal supported catalysts, bimetallic alloy materials such as Au-Ag, Au-Cu, Pt-Sn, Ag-Au, Mn-Co, etc., and also semiconductors such as CdSe, CdS, PbS, etc., that have uniform particle sizes in nanoscale dimensions. A further important aspect of the SMAD method is that it leads to the production of high purity materials (with no formation of byproducts) and most importantly the materials produced are highly monodisperse (uniform particle sizes).

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www.soran.edu.iq A popular method of preparation of Au nanoparticle was first reported by Turkevich in 1951. This method relied on the use of a reducing agent, citrate ions, to reduce Au 3+ ions in aqueous solution. The original recipe reported by Turkevich led to the synthesis of Au nanoparticles that were spherical in shape with a particle diameter of ~20 nm.

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www.soran.edu.iq Nanostructures: 1.Carbon nanofibers (CNFs) 2.Nanoporous Materials 3.Nanofiber 4.Supramolecular chemistry 5.Metallic nanostructures 6.

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www.soran.edu.iq Carbon nanofibers (CNFs) vapor grown carbon fibers (VGCFs), or vapor grown carbon nanofibers (VGCNFs) are cylindric nanostructures with graphene layers arranged as stacked cones, cups or plates. Carbon nanofibers with graphene layers wrapped into perfect cylinders are called carbon nanotubes. VGCFs (Vapor Grown Carbon Fiber) and their smaller size variant, VGCNFs (Vapor Grown Carbon Nanofiber) are among short carbon fibers that have drawn lots of attention for their potential thermal, electrical, frequency shielding, and mechanical property enhancements.

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Nanoporous Materials Porous materials are of scientific and technological importance because of the presence of voids of controllable dimensions at the atomic, molecular, and nanometer scales, enabling them to discriminate and interact with molecules and clusters. The main challenges in research include the fundamental understanding of structure-property relations and tailor- design of nanostructures for specific properties and applications. Research efforts in this field have been driven by the rapid growing emerging applications such as biosensor, drug delivery, gas separation, energy storage and fuel cell technology, nanocatalysis and photonics.

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www.soran.edu.iq International Union of Pure and Applied Chemistry (IUPAC) classifies porous materials into three categories: A.macropores of greater than '50 nm. B.mesopores between 2 and 50 nm C.micropores of less than 2 nm in diameter

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www.soran.edu.iq Nanofiber Nanofibers are defined as fibers with diameters less than 100 nanometers. In the textile industry, this definition is often extended to include fibers as large as 1000 nm diameter. They can be produced by interfacial polymerization, electrospinning, and forcespinning. Carbon nanofibers are graphitized fibers produced by catalytic synthesis.

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www.soran.edu.iq How are Nanofibers Formed? One of the commonly utilized methods for the production of nanofibers is electrospinning. The electrospinning process has a few key elements: a power supply, a reservoir for containing the polymeric solution, and a grounded collector.

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www.soran.edu.iq Supramolecular chemistry Supramolecular chemistry refers to the domain of chemistry beyond that of molecules and focuses on the chemical systems made up of a discrete number of assembled molecular subunits or components. While traditional chemistry focuses on the covalent bond, supramolecular chemistry examines the weaker and reversible noncovalent interactions between molecules. These forces include hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-pi interactions and electrostatic effects.hydrogen bondingmetal coordinationhydrophobic forcesvan der Waals forcespi-pi interactionselectrostatic

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www.soran.edu.iq It shows a p- xylylenediammonium bound within a cucurbit uril. It shows a chlorine anion bound within a cucurbit[5]uril that both are bound within cucurbit[10]uril. The complex was described as a molecular gyroscope.

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www.soran.edu.iq Metallic nanostructures Nanocrystals are crystals with at least one dimension between 1 and 100 nm. Metals also possess a range of wonderful properties, and many metals have found extensive use in applications that include catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in a finely divided state, preferably in the form of nanocrystals with precisely controlled properties.

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www.soran.edu.iq The properties of a metal nanocrystal are determined by a set of physical parameters that may include its size, shape, composition, and structure (e.g., solid versus hollow). In principle, one can tailor and fine-tune the properties of a metal nanocrystal by controlling any one of these parameters, but the flexibility and scope of change are highly sensitive to the specific parameter. In the case of catalysis, it is well-established that the activity of a metal nanocrystal can be enhanced by reducing its size. For example, Pt can selectively catalyze different types of chemical reactions, with the {100} and {210} facets being most active for reactions involving H 2 and CO, respectively.

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www.soran.edu.iq Examples of metal nanostructures: Pd long nanowires (left) and Ag nanowires (right) Gold nanostructures: Au nanotubes (left) and Au nanowires (right)

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