Реферат: Nanotechnology and polymer nanocomposites

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<span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">MINISTRYOF HIGHER AND SECONDARY SPECIAL EDUCATION

<st1:place w:st=«on»><st1:PlaceName w:st=«on»><span a_FuturicaBook",«sans-serif»;mso-bidi-font-family: Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">TASHKENT

</st1:PlaceName><span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold"> <st1:PlaceType w:st=«on»>STATE</st1:PlaceType> <st1:PlaceName w:st=«on»>TECHNICAL</st1:PlaceName> <st1:PlaceType w:st=«on»>UNIVERSITY</st1:PlaceType></st1:place><span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">

<span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">SCIENTIFIC-TECHNOLOGICALCOMPLEX

<span BankGothic Lt BT",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US">REPORT

<span BankGothic Lt BT",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US">NANOTECHNOLOGY

<span BankGothic Lt BT",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US">& NANOCOMPOSITES

<span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">

<span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">Preparedby: 2nd year post-graduate student RahimovG.N.

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<st1:place w:st=«on»><st1:PlaceName w:st=«on»><span a_FuturicaBook",«sans-serif»;mso-bidi-font-family:Tahoma; mso-ansi-language:EN-US;mso-bidi-font-weight:bold">Tashkent

</st1:PlaceName><span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold"> <st1:PlaceType w:st=«on»>City</st1:PlaceType></st1:place><span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US;mso-bidi-font-weight:bold">  — May, 2006
<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family:Tahoma; mso-ansi-language:EN-US">TABLE OF CONTENTS<span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US">

<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family: Tahoma;mso-ansi-language:EN-US"> TOC o «1-3» h z u

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">NANOTECHNOLOGY. PAGEREF _Toc136068288 h 3

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">History of use. PAGEREF _Toc136068289 h 4

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Potential benefits. PAGEREF _Toc136068290 h 5

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Potential risks. PAGEREF _Toc136068291 h 6

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Manufacturing… PAGEREF _Toc136068292 h 6

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Key Characteristics. PAGEREF _Toc136068293 h 7

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Problems. PAGEREF _Toc136068294 h 8

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Interdisciplinarian ensemble. PAGEREF _Toc136068295 h 9

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Prominent individuals in nanotechnology. PAGEREF _Toc136068296 h 10

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">NANOCOMPOSITES. PAGEREF _Toc136068297 h 11

<span a_FuturicaBook",«sans-serif»">Introduction. PAGEREF _Toc136068298 h 11

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Polymer Nanocomposites. PAGEREF _Toc136068299 h 12

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">PNC Framework. PAGEREF _Toc136068300 h 15

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Properties And Applications of PNC’S. PAGEREF _Toc136068301 h 16

<span a_FuturicaBook",«sans-serif»">Advantages<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US"> of Nanosized Additions. PAGEREF _Toc136068302 h 16

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Disadvantages of Nanosized Additions. PAGEREF _Toc136068303 h 16

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Particle Loadings. PAGEREF _Toc136068304 h 17

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Areas of Application. PAGEREF _Toc136068305 h 17

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Gas Barriers. PAGEREF _Toc136068306 h 18

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Oxygen Barriers. PAGEREF _Toc136068307 h 18

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Food Packaging… PAGEREF _Toc136068308 h 19

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Fuel Tanks. PAGEREF _Toc136068309 h 19

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Films. PAGEREF _Toc136068310 h 20

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Environmental Protection. PAGEREF _Toc136068311 h 20

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Flammability Reduction. PAGEREF _Toc136068312 h 21

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Conclusion. PAGEREF _Toc136068313 h 22

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">REFERENCES. PAGEREF _Toc136068314 h 24

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">INTERNET SOURCES. PAGEREF _Toc136068315 h 24

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">TRANSLATION… PAGEREF _Toc136068316 h 25

<span a_FuturicaBook",«sans-serif»">НАНОТЕХНОЛОГИЯ… PAGEREF _Toc136068317 h 26

<span a_FuturicaBook",«sans-serif»">История. PAGEREF _Toc136068318 h 27

<span a_FuturicaBook",«sans-serif»">Открытия,сделанные в области нанотехнологий… PAGEREF _Toc136068319 h 28

<span a_FuturicaBook",«sans-serif»">Наночастицы… PAGEREF _Toc136068320 h 28

<span a_FuturicaBook",«sans-serif»">Атомно-силоваямикроскопия. PAGEREF _Toc136068321 h 29

<span a_FuturicaBook",«sans-serif»">Самоорганизациянаночастиц… PAGEREF _Toc136068322 h 29

<span a_FuturicaBook",«sans-serif»">Проблемаобразования агломератов. PAGEREF _Toc136068323 h 30

<span a_FuturicaBook",«sans-serif»">Новейшиедостижения. PAGEREF _Toc136068324 h 30

<span a_FuturicaBook",«sans-serif»">Графен… PAGEREF _Toc136068325 h 30

<span a_FuturicaBook",«sans-serif»">Транзисториз нанотрубок. PAGEREF _Toc136068326 h 31

<span a_FuturicaBook",«sans-serif»">Новыйпроцессор IntelPAGEREF _Toc136068327 h 31

<span a_FuturicaBook",«sans-serif»">Плазмон… PAGEREF _Toc136068328 h 31

<span a_FuturicaBook",«sans-serif»">Антенна-осциллятор… PAGEREF _Toc136068329 h 32

<span a_FuturicaBook",«sans-serif»">Экономическоеразвитие индустрии в сфере нанотехнологий… PAGEREF _Toc136068330 h 32

<span a_FuturicaBook",«sans-serif»">Известныеличности в сфере нанотехнологий… PAGEREF _Toc136068331 h 32

<span a_FuturicaBook",«sans-serif»">Использованнаялитература и ссылки… PAGEREF _Toc136068332 h 33

<span a_FuturicaBook",«sans-serif»">Интернетисточники… PAGEREF _Toc136068333 h 33

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">NANOTECHNOLOGY<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family:Frutiger-Roman; mso-ansi-language:EN-US">Nanotechnology research is generating a variety of constructs, giving researchers great flexibility in their efforts to change the paradigm

. <span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Frutiger-Roman;mso-ansi-language:EN-US"> Shown here are two such structures. On the left are highly stable nanoparticles. On the right are spherical dendrimers, which are of rigorously defined size based on the number of monomer layers. Like most of the other nanoparticles being developed, these are easily manipulated, affording researchers the opportunity to add a variety of molecules to the surfaces and interiors of the nanoparticles.<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family:Frutiger-Roman; mso-ansi-language:EN-US">

<img src="/cache/referats/22198/image003.gif" align=«left» hspace=«12» v:shapes="_x0000_s1052"><img src="/cache/referats/22198/image005.gif" align=«left» hspace=«12» v:shapes="_x0000_s1048"><span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Nanotechnology comprises technological developments onthe nanometer scale, usually 0.1 to 100 nm (1/1,000 µm, or 1/1,000,000 mm). Apossible way to interpret this size is to take the width of a hair, and imaginesomething ten thousand times smaller. The term has sometimes been applied tomicroscopic technology. Nanotechnology is any technology which exploitsphenomena and structures that can only occur at the nanometer scale, which isthe scale of several atoms and small molecules. The <st1:place w:st=«on»><st1:country-region w:st=«on»>United States</st1:country-region></st1:place>' NationalNanotechnology Initiative website [1] defines it as follows:«Nanotechnology is the understanding and control of matter at dimensionsof roughly 1 to 100 nanometers, where unique phenomena enable novelapplications.» Such phenomena include quantum confinement--which canresult in different electromagnetic and optical properties of a materialbetween nanoparticles and the bulk material; theGibbs-Thomson effect--which is the lowering of the melting point of a materialwhen it is nanometers in size; and such structures as carbon nanotubes.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Nanoscience

<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US"> and nanotechnology are an extension of the field of materials science,and materials science departments at universities around the world inconjunction with physics, mechanical engineering, bioengineering, and chemicalengineering departments are leading the breakthroughs in nanotechnology. Therelated term nanotechnology is used to describe the interdisciplinary fields ofscience devoted to the study of nanoscale phenomenaemployed in nanotechnology. Nanoscience is the worldof atoms, molecules, macromolecules, quantum dots, and macromolecularassemblies, and is dominated by surface effects such as Van derWaals force attraction, hydrogen bonding, electroniccharge, ionic bonding, covalent bonding, hydrophobicity,hydrophilicity, and quantum mechanical tunneling, tothe virtual exclusion of macro-scale effects such as turbulence and inertia.For example, the vastly increased ratio of surface area to volume opens newpossibilities in surface-based science, such as catalysis.<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">History of use<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Richard Feynman,

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">physicist

<img src="/cache/referats/22198/image006.gif" align=«left» hspace=«19» v:shapes="_x0000_s1031"><img src="/cache/referats/22198/image008.gif" align=«left» hspace=«19» v:shapes="_x0000_s1030"><span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">The first mention of some of the distinguishing concepts innanotechnology (but predating use of that name) was in «There's Plenty ofRoom at the Bottom,» a talk given by physicist Richard Feynman at anAmerican Physical Society meeting at Caltech on December 29, 1959. Feynmandescribed a process by which the ability to manipulate individual atoms andmolecules might be developed, using one set of precise tools to build andoperate another proportionally smaller set, so on down to the needed scale. Inthe course of this, he noted, scaling issues would arise from the changingmagnitude of various physical phenomena: gravity would become less important,surface tension and Van der Waalsattraction would become more important, etc. This basic idea appears feasible,and exponential assembly enhances it with parallelism to produce a usefulquantity of end products.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The term «nanotechnology» was defined byTokyo Science University Professor Norio Taniguchi in a 1974 paper (N.Taniguchi, «On the Basic Concept of 'Nano-Technology',»Proc. Intl. Conf. Prod. <st1:country-region w:st=«on»>Eng.</st1:country-region><st1:City w:st=«on»>Tokyo</st1:City>, Part II, <st1:place w:st=«on»><st1:country-region w:st=«on»>Japan</st1:country-region></st1:place> Society of PrecisionEngineering, 1974.) as follows: "'Nano-technology'mainly consists of the processing of, separation, consolidation, and deformationof materials by one atom or one molecule." In the 1980s the basic idea ofthis definition was explored in much more depth by Dr. Eric Drexler,who promoted the technological significance of nano-scalephenomena and devices through speeches and the books Engines of Creation: TheComing Era of Nanotechnology and Nanosystems:Molecular Machinery, Manufacturing, and Computation, (ISBN 0-471-57518-6), andso the term acquired its current sense.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">More broadly, nanotechnology includes the manytechniques used to create structures at a size scale below 100 nm, includingthose used for fabrication of nanowires, those usedin semiconductor fabrication such as deep ultraviolet lithography, electronbeam lithography, focused ion beam machining, nanoimprintlithography, atomic layer deposition, and molecular vapor deposition, andfurther including molecular self-assembly techniques such as those employing di-block copolymers. It should be noted, however, that allof these techniques preceded the nanotech era, and are extensions in thedevelopment of scientific advancements rather than techniques which weredevised with the sole purpose of creating nanotechnology or which were resultsof nanotechnology research.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Technologies currently branded with the term 'nano' are little related to and fall far short of the mostambitious and transformative technological goals of the sort in molecularmanufacturing proposals, but the term still connotes such ideas. Thus there maybe a danger that a "nano bubble" will formfrom the use of the term by scientists and entrepreneurs to garner funding,regardless of (and perhaps despite a lack of) interest in the transformativepossibilities of more ambitious and far-sighted work. The diversion of supportbased on the promises of proposals like molecular manufacturing to more mundaneprojects also risks creating a perhaps unjustifiedlycynical impression of the most ambitious goals: an investor intrigued bymolecular manufacturing who invests in 'nano' only tofind typical materials science advances result might conclude that the wholeidea is hype, unable to appreciate the bait-and-switch made possible by thevagueness of the term. On the other hand, some have argued that the publicityand competence in related areas generated by supporting such 'soft nano' projects is valuable, even if indirect, progresstowards nanotechnology's most ambitious goals.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Potential benefits<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US;font-weight:normal;mso-bidi-font-style:normal"> <span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Nanotechnology covers a wide range of industries, andtherefore the potential benefits are also widespread. Telecommunications andInformation technology could benefit in terms of faster computers and advanceddata storage.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Healthcare could see improvements in skin care andprotection, advanced pharmaceuticals, drug delivery systems, biocompatiblematerials, nerve and tissue repair, and cancer treatments.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Other industries benefits include catalysts, sensorsand magnetic materials and devices.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Potential risks<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">For the near-term, critics of nanotechnology point tothe potential toxicity of new classes of nanosubstancesthat could adversely affect the stability of cell membranes or disturb theimmune system when inhaled, digested or absorbed through the skin. Objectiverisk assessment can profit from the bulk of experience with long-knownmicroscopic materials like carbon soot or asbestos fibres.Nanoparticles in the environment could potentiallyaccumulate in the food chain.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">An often cited worst-case scenario is «grey goo», a hypothetical substance into which the surfaceobjects of the earth might be transformed by self-replicating nanobots running amok.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Societal risks from the use of nanotechnology havealso been raised, such as hypothetical nanotech weapons (e.g., a nanomachine that consumed the rubber in tires would quicklydisable many vehicles), and in the creation of undetectable surveillancecapabilities.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Manufacturing<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">When the term «nanotechnology» wasindependently coined and popularized by Eric Drexler,who at the time was unaware of Taniguchi's usage, it referred to a futuremanufacturing technology based on molecular machine systems. The premise wasthat molecular-scale biological analogies of traditional machine componentsdemonstrated that molecular machines were possible, and that a manufacturingtechnology based on the mechanical functionality of these components (such asgears, bearings, motors, and structural members) would enable programmable,positional assembly to atomic specification (see the original referencePNAS-1981). The physics and engineering performance of exemplar designs wereanalyzed in the textbook Nanosystems.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Because the term «nanotechnology» wassubsequently applied to other uses, new terms evolved to refer to this distinctusage: «molecular nanotechnology,» «molecularmanufacturing,» and most recently, «productive nanosystems.»

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">One alternative view is that designs such as thoseproposed by Drexler and Merkledo not accurately account for the electrostatic interactions and will notoperate according to the results of the analysis in Nanosystems.The contention is that man-made nanodevices willprobably bear a much stronger resemblance to other (less mechanical) nanodevices found in nature: cells, viruses, and prions. This idea is explored by Richard A. L. Jones in hisbook Soft Machines: Nanotechnology and Life (ISBN 0-19-852855-8).

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Another view, put forth by Carlo Montemagno,is that future nanosystems will be hybrids of silicontechnology and biological molecular machines, and his group's research isdirected toward this end.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The seminal experiment proving that positionalmolecular assembly is possible was performed by Ho and Lee at <st1:place w:st=«on»><st1:PlaceName w:st=«on»>Cornell</st1:PlaceName> <st1:PlaceType w:st=«on»>University</st1:PlaceType></st1:place>in 1999. They used a scanning tunneling microscope to move an individual carbonmonoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silvercrystal, and chemically bind the CO to the Fe by applying a voltage.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Though biology clearly demonstrates that molecularmachine systems are possible, non-biological molecular machines are today onlyin their infancy. Leaders in research on non-biological molecular machines areDr. Alex Zettl and his groups at Lawrence BerkeleyLaboratories and UC Berkeley. They have constructed at least three distinctmolecular devices whose motion is controlled from the desktop with changingvoltage: a rotating molecular motor, a molecular actuator, and a nanoelectromechanical relaxation oscillator.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Manufacturing in the context of productive nanosystems is not related to, and should be clearlydistinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubesand nanoparticles.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Key Characteristics<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Some nanodevicesself-assemble. That is, they are built by mixing two or more complementary andmutually attractive pieces together so they make a more complex and usefulwhole. Other nanodevices must be built piece by piecein stages, much as manufactured items are currently made. Scanning probemicroscopy is an important technique both for characterization and synthesis ofnanomaterials. Atomic force microscopes and scanningtunneling microscopes can be used to look at surfaces and to move atoms around.By designing different tips for these microscopes, they can be used for carvingout structures on surfaces and to help guide self-assembling structures. Atomscan be moved around on a surface with scanning probe microscopy techniques, butit is cumbersome, expensive and very time-consuming, and for these reasons itis quite simply not feasible to construct nanoscaleddevices atom by atom. You don't want to assemble a billion transistors into amicrochip by taking an hour to place each transistor, but these techniques mayeventually be used to make primitive nanomachines,which in turn can be used to make more sophisticated nanomachines.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Natural or man-made particles or artifacts often havequalities and capabilities quite different from their macroscopic counterparts.Gold, for example, which is chemically inert at normal scales, can serve as apotent chemical catalyst at nanoscales.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">"Nanosize" powderparticles (a few nanometres in diameter, also called nano-particles) are potentially important in ceramics,powder metallurgy, the achievement of uniform nanoporosity,and similar applications. The strong tendency of small particles to form clumps(«agglomerates») is a serious technological problem that impedes suchapplications. However, a few dispersants such as ammonium citrate (aqueous) andimidazoline or oleylalcohol (nonaqueous) are promising additives for deagglomeration. (Those materials are discussed in«Organic Additives And Ceramic Processing,» by Daniel J. Shanefield, Kluwer Academic Publ., <st1:place w:st=«on»><st1:City w:st=«on»>Boston</st1:City></st1:place>.)

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Problems<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">One of the problems facing nanotechnology concerns howto assemble atoms and molecules into smart materials and working devices. Supramolecular chemistry, a very important tool here, isthe chemistry beyond the molecule, and molecules are being designed toself-assemble into larger structures. In this case, biology is a place to findinspiration: cells and their pieces are made from self-assembling biopolymerssuch as proteins and protein complexes. One of the things being explored issynthesis of organic molecules by adding them to the ends of complementary DNAstrands such as ----A and ----B, with molecules A and B attached to the end;when these are put together, the complementary DNA strands hydrogen bonds intoa double helix, ====AB, and the DNA molecule can be removed to isolate theproduct AB.

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<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Advancednanotechnology

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<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family:Frutiger-Roman; mso-ansi-language:EN-US">An array of carbon nanotubes provides an addressable platform for probing intact, living cells.

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<img src="/cache/referats/22198/image011.gif" align=«left» hspace=«12» v:shapes="_x0000_s1028"><span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Advancednanotechnology, sometimes called molecular manufacturing, is a term given tothe concept of engineered nanosystems (nanoscale machines) operating on the molecular scale. Bythe countless examples found in biology it is currently known that billions ofyears of evolutionary feedback can produce sophisticated, stochasticallyoptimized biological machines, and it is hoped that developments innanotechnology will make possible their construction by some shorter means,perhaps using biomimetic principles. However, K Eric Drexler and other researchers have proposed that advancednanotechnology, although perhaps initially implemented by biomimeticmeans, ultimately could be based on mechanical engineering principles.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">In August <st1:metricconverter ProductID=«2005, a» w:st=«on»>2005, a</st1:metricconverter> task force consisting of 50+international experts from various fields was organized by the Center forResponsible Nanotechnology to study the societal implications of molecularnanotechnology [4].

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Determining a set of pathways for the development ofmolecular nanotechnology is now an objective of a broadly based technologyroadmap project [5] led by Battelle (the manager ofseveral U.S. National Laboratories) and the Foresight Institute. That roadmapshould be completed by early 2007.

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<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Interdisciplinarian<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US"> ensemble<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">A definitive feature of nanotechnology is that itconstitutes an interdisciplinary ensemble of several fields of the naturalsciences that are, in and of themselves, actually highly specialized. Thus,physics plays an important role—alone in the construction of the microscopeused to investigate such phenomena but above all in the laws of quantummechanics.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Prominent individuals in nanotechnology<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">RichardFeynman — gave the first mention of some of the distinguishing concepts in a1959 talk

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">NorioTaniguchi — defined the term «nanotechnology»

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">K.Eric Drexler — promoted the technologicalsignificance, described Grey goo scenario

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">RobertFreitas — nanomedicinetheorist

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">RalphMerkle — nanotechnology theorist

<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Sumio

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US"> Iijima — discoverer of nanotubes

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">RichardSmalley — co-discoverer of buckminsterfullerene

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">HarryKroto — co-discoverer of buckminsterfullerene

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">ErwinM<span Times New Roman",«serif»">üller — invented the field ion microscope, and the atom probe.

<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Gerd

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US"> Binnig — co-inventor of thescanning tunneling microscope

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">HeinrichRohrer — co-inventor of the scanning tunneling microscope

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Paul Alivisatos — Director of the Materials Sciences Division atthe <st1:City w:st=«on»>Lawrence</st1:City> <st1:City w:st=«on»><st1:place w:st=«on»>Berkeley</st1:place></st1:City> National Laboratory

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">ChrisPhoenix — co-founder of the Center for Responsible Nanotechnology

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Mike Treder — co-founder of the Center for ResponsibleNanotechnology

<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Phaedon

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US"> Avouris — first electronicdevices made out of carbon nanotubes

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">Alex Zettl — Built the first molecular motor based on carbon nanotubes

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">NANOCOMPOSITES<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

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<span a_FuturicaBook",«sans-serif»;mso-bidi-font-family: Tahoma;mso-ansi-language:EN-US"> A rapidly growing area of nano-engineered materials provides a new dimension for plastics andcomposites

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Introduction<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US"> <span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US">

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The definition of nano-compositematerial has broadened significantly to encompass a large variety of systemssuch as one-dimensional, two-dimensional, three-dimensional and amorphousmaterials, made of distinctly dissimilar components and mixed at the nanometerscale.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The general class of nanocompositeorganic/inorganic materials is a fast growing area of research. Significanteffort is focused on the ability to obtain control of the nanoscalestructures via innovative synthetic approaches. The properties of nano-composite materials depend not only on the propertiesof their individual parents but also on their morphology and interfacialcharacteristics.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">This rapidly expanding field is generating manyexciting new materials with novel properties. The latter can derive bycombining properties from the parent constituents into a single material. Thereis also the possibility of new properties which are unknown in the parentconstituent materials.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The inorganic components can be three-dimensionalframework systems such as zeolites, two-dimensionallayered materials such as clays, metal oxides, metal phosphates, chalcogenides, and even one-dimensional andzero-dimensional materials such as (Mo3Se3-)nchains and clusters. Experimental work has generally shown that virtually alltypes and classes of nanocomposite materials lead tonew and improved properties when compared to their macrocompositecounterparts. Therefore, nanocomposites promise newapplications in many fields such as mechanically reinforced lightweightcomponents, non-linear optics, battery cathodes and ionics,nano-wires, sensors and other systems.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The general class of organic/inorganic nanocomposites may also be of relevance to issues ofbio-ceramics and biomineralization in which in-situgrowth and polymerization of biopolymer and inorganic matrix is occurring.Finally, lamellar nanocomposites represent an extremecase of a composite in which interface interactions between the two phases aremaximized. Since the remarkable properties of conventional composites aremainly due to interface interactions, the materials dealt with here couldprovide good model systems in which such interactions can be studied in detailusing conventional bulk sample (as opposed to surface) techniques. Byjudiciously engineering the polymer-host interactions, nanocompositesmay be produced with a broad range of properties.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Inorganic layered materials exist in great variety.They possess well defined, ordered intralamellarspace potentially accessible by foreign species. This ability enables them toact as matrices or hosts for polymers, yielding interesting hybrid nano-composite materials.

 <span a_FuturicaBook",«sans-serif»; mso-bidi-font-family:Tahoma;mso-ansi-language:EN-US"><span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Polymer <span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Nanocomposites<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">

<img src="/cache/referats/22198/image013.gif" align=«left» hspace=«12» v:shapes="_x0000_s1040"><span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Materials and their development are fundamental to society. Majorhistorical periods of society are ascribed to materials (i.e., stone age,bronze age, iron age, steel age [industrial revolution]; silicon age and silicaage [telecom revolution]). Scientists will open the next societal frontiers notby understanding a particular material, but rather by understanding andoptimizing the relative contributions afforded by material combinations.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The nanoscale, and theassociated excitement surrounding nanoscience andtechnology, affords unique opportunities to create these revolutionary materialcombinations. These new materials promise to enable the circumvention ofclassic material performance trade-offs by accessing new properties andexploiting unique synergisms between constituents that only occur when thelength scale of the morphology and the critical length associated with thefundamental physics of a given property coincide. From a materials perspective,morphologies that exhibit nanoscopic features arenecessary but far from sufficient – the key opportunities are afforded eitherwhen the physical size of the material’s constituents is engineered to coincidewith the onset of nonbulk-like behavior, such asobserved for the size-dependent light emission of quantum dots (QDs), or  when astructure-property relationship approaches a singularity or depends nonlinearlyon aspects of the morphology, such as the internal interfacial area.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Polymeric nanocomposites (PNCs) have been an area of intense industrial and academicresearch for the past 20 years. No matter the measure – articles, patents, orR&D funding – efforts in PNCs have beenexponentially growing worldwide over the last ten years. PNCsrepresent a radical alternative to conventional filled polymers or polymerblends – a staple of the modern plastics industry.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">The reinforcement of polymers using fillers, whetherinorganic or organic, is common in the production of modern plastics. Polymericnanocomposites or polymer nanostructuredmaterials represent a radical alternative to conventional-filled polymers orpolymer blends. In contrast to the conventional systems where the reinforcementis on the order of microns, discrete constituents on the order of a fewnanometers (~10,000 times finer than a human hair) exemplify PNCs.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Uniform dispersion of these nanoscopicallysized filler particles (or nanoelements) producesultra-large interfacial area per volume between the nanoelementand host polymer. This immense internal interfacial area and the nanoscopic dimensions between nanoelementsfundamentally differentiate PNCs from traditionalcomposites and filled plastics. Thus, new combinations of properties derivedfrom the nanoscale structure of PNCsprovide opportunities to circumvent traditional performance trade-offsassociated with conventional reinforced plastics, epitomizing the promise of nano-engineered materials.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">A literature search provides many examples of PNCs, demonstrating substantial improvements in mechanicaland physical properties. However, the nanocompositeproperties discussed are generally compared to unfilled and conventional-filledpolymers, but are not compared to continuous fiber reinforced composites.Although PNCs may provide enhanced, multifunctionalmatrix resins, they should not be considered a potential one-for-onereplacement for current state-of-the-art carbon-fiber reinforced composites.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">From both a commercial and military perspective, thevalue of PNC technology is not based solely on mechanical enhancements of theneat resin. Rather, it comes from providing value-added properties not presentin the neat resin, without sacrificing the inherent processibilityand mechanical properties of the resin. Traditionally, blend or compositeattempts at multifunctional materials require a trade-off between desiredperformance, mechanical properties, cost, and processibility.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Considering the number of potential nanoelements, polymeric resins, and applications, the fieldof PNCs is immense. Development of multicomponent materials, whether microscaleor nanoscale, must simultaneously balance fourinterdependent areas: constituent-selection, fabrication, processing, andperformance. This is still in its infancy for PNCs,but ultimately scientists will develop many perspectives dictated by the finalapplication of the PNC. Researchers developed two main PNC fabricationmethodologies: in-situ routes and exfoliation. Currently, researchers inindustry, government, and academia worldwide are heavily investigatingexfoliation of layered silicates, carbon nanofibers/nanotube-polymernanocomposites, and high-performance resin PNCs.

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US;mso-bidi-font-weight: bold">This picture shows the complex arrangement of the copper conductors in a computer chip. The smallest wires are less than a millionth of a meter in diameter. Copper is starting to replace aluminum in computer chips because it conducts electricity

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US;mso-bidi-font-weight: bold">better (better performance!) and has a higher melting temperature (lasts longer!).

<span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US;mso-bidi-font-weight: bold">It took many years of  materials science research worldwide to figure out how to produce chips with copper conductors.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">

<img src="/cache/referats/22198/image014.gif" align=«left» hspace=«12» v:shapes="_x0000_s1043"><img src="/cache/referats/22198/image016.gif" align=«left» hspace=«12» v:shapes="_x0000_s1042"><span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US">Notwithstanding the considerable advances in exfoliated PNCs, scientists must still conduct substantial fundamentalresearch to provide a basic understanding of these materials to enable fullexploitation of their nano-engineering potential.Despite the large number of combinations of matrices and potential reinforcing nanoelements with different chemistry, size, shape, andproperties, all PNCs share common features withregard to fabrication methodologies, processing, morphology characterization,and fundamental physics.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">Developing an understanding of the characteristics ofthis interphase region, its dependence on nanoelement surface chemistry, the relative arrangement ofconstituents and, ultimately, its relationship to the PNC properties, is acurrent research frontier in nanocomposites. Equallyimportant is the development of a general understanding of the morphology-propertyrelationships for mechanical, barrier, and thermal response of these systems.This necessitates the determination of the critical length and temporal scalewith which continuum description of a physical process must give way to mesoscopic and atomistic view of these nanoscalesystems—a current challenge for computational materials science.

<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">A rapidly growing area of nano-engineeredmaterials is PNCs, providing lighter weightalternatives to conventional-filled plastics with additional functionalityassociated with nanoscale-specific value-addedproperties. If the promise and excitement surrounding layered silicates andcarbon nanotubes are any indication, the future ofPNC technology is truly boundless. The opportunities to extend PNC concepts toother nanoelements and polymer hosts are immense,opening the way to provide tailor-made materials that circumvent currentlimitations and enable future concepts.

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<span a_FuturicaBook",«sans-serif»; mso-ansi-language:EN-US">PNC Framework<span a_FuturicaBook",«sans-serif»;mso-ansi-language: EN-US;font-weight:normal;mso-bidi-font-style:normal"> <span a_FuturicaBook",«sans-serif»;mso-ansi-language:EN-US"></h
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