Item description for Elementorganic Monomers: Technology, Properties, Applications (New Concepts in Polymer Science) by L. M. Khananashvili, O. V. Mukbaniani & G. E. Zaikov...
New fields of science and technology call for new materials with valuable performance characteristics. Long-term resistance to such temperatures can be found only in polymers with chains made up of thermostable fragments. Particularly interesting in this respect are elementorganic polymers with inorganic and organo-inorganic molecular chains.
Elementorganic polymers are not only highly thermostable, but also perform well under low temperatures, sunlight, humidity, weather, etc. Thus, these polymers (especially silicones) are widely and effectively used in the electrical, radio, coal, mechanical rubber, aircraft, metallurgical, textile and other industries. They are of great utility not only in industry, but also in households and in medicine, where their merits can hardly be overestimated.
The need to publish this book arose with the scientific and technical developments of the last decade, the reconstruction and technical renovation of existing factories, as well as fundamental changes in some syntheses of elementorganic monomers and polymers. Moreover, nowadays it is essential to train highly-skilled chemical engineers with a comprehensive knowledge of current chemistry, of the production technology of elementorganic monomers and polymers, and of their characteristics and applications.
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Studio: Brill Academic Publishers
Est. Packaging Dimensions: Length: 9.5" Width: 6.4" Height: 1.5" Weight: 2.2 lbs.
Release Date Jun 15, 2006
Publisher Brill Academic Publishers
ISBN 9004152601 ISBN13 9789004152601
Availability 0 units.
More About L. M. Khananashvili, O. V. Mukbaniani & G. E. Zaikov
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More Practical Applications in Polymer Science Aug 29, 2006
The chemical industry in our country and abroad is rapidly developing. It is only natural that the young industry of elementorganic monomers, oligomers and polymers should develop at the same rate. The numerous valuable and sometimes unique properties of these substances account for their wide application in various industries, households, medicine and cutting-edge technologies. That is why contemporary industry produces more than 500 types of silicone monomers, oligomers and polymers, to say nothing of other elementorganic compounds. The synthesis of these elementorganic compounds is based on many different reactions. New fields of science and technology, the use of high and ultra low temperatures, high pressures and high vacuum, the developments in electrification, mechanical engineering, radio engineering and radio electronics, the design of supersonic aeroplanes and artificial Earth satellites - all this calls for new materials with valuable performance characteristics. It is well known that the surface of load-carrying machine parts at very high speeds can heat to 300°C upwards. Long-term resistance to such temperatures can be found only in polymers with chains made up of thermostable fragments. Particularly interesting in this respect are elementorganic polymers with inorganic and organo-inorganic molecular chains.
Elementorganic polymers are not only highly thermostable, but also perform well under low temperatures, sunlight, humidity, weather, etc. Besides, their physics and chemistry change little in a wide temperature range. Thus, these polymers (especially silicones) are widely and effectively used in the electrical, radio, coal, mechanical rubber, aircraft, metallurgical, textile and other industries. They are of great utility not only in industry, but also in households and in medicine, where their merits can hardly be overestimated. Silicone polymers can render various materials unwettable (hydrophobic), which can be used in the manufacture of waterproof clothes, shoes, and construction materials. Silicone antifoam agents destroy foam, which is difficult to deal with in many spheres (in pharmaceutics, as well as in sugar-refining, wine-making and other food industries). They are indispensable even in contemporary medicine: these substances help to eliminate blood foaming during major surgeries, when great amounts of blood have to be drawn from the body. In this case, if surgical instruments are treated with silicone oligomers, there is no danger of tiny air bubbles (thrombi) entering blood and causing immediate death. Silicone oligomers are also widely used in the production of hydraulic fluids and lubricants to assure the performance of devices in a wide temperature range (from -120-140 to 250-350°C).
Each year sees more and more silicone elastomers used in the production of thermostable rubbers, and silicone polymers of various composition used for nonmetal composites. At present there are few industries where silicone polymers and materials based on them are not used to a greater or lesser extent. With that in mind, it is small wonder that the silicone industry is gathering such momentum all over the world. Other elementorganic compounds, e.g. organoaluminum compounds, are extremely valuable components of the Ziegler-Natta catalysts, widely used in the production of stereoregular polymers. They are also used in the synthesis of higher fatty alcohols, carboxylic acids, a-olefines, cycloolefines and other important compounds. Organotin compounds are increasingly used as catalysts, as stabilizers for polymers and polymer-based materials, etc. Organolead compounds, tetraalkyl derivatives in particular, are used as antiknock substances in engine fuels. Organophosphorus compounds have found a wide application as pesticides, plasticizers and fire-resistant agents in polymers This list, by no means complete, testifies to a constantly growing role of elementorganic compounds in industry, economy and households, which is to promote further development of the technology of elementorganic compounds. The need to publish this book arose with the scientific and technical developments of the last decade, the reconstruction and technical renovation of existing factories, as well as fundamental changes in some syntheses of elementorganic monomers and polymers. Moreover, nowadays it is essential to train highly-skilled chemical engineers with a comprehensive knowledge of current chemistry, of the production technology of elementorganic monomers and polymers, and of their characteristics and applications. One of the most important contemporary features of scientific and technological advance is a wide use of polymers and polymer-based materials virtually in all spheres of economy and in households; moreover, the application range of synthetic materials is wider every year. Thus, further development of economy requires an increased production of various polymer materials with valuable properties. Many polymer materials are based on synthetic elementorganic oligomers and polymers used in the manufacture of plastics, sealants and rubbers; paint, anticorrosive and other coatings; insulating, lubricating and construction materials, etc. Nowadays it is hard to find an industry which does not use elementorganic compounds, because their valuable technical characteristics are combined with convenient and highly productive techniques to process them into materials and products of various shapes and sizes. All this promises a big future to elementorganic oligomers and polymers. Carbon-chain superpolymers (with chains consisting only of carbon atoms) are as a rule not heat- and weather-resistant enough; that is why synthetic chemists have always aimed to synthesise new, more heat- and weather-resistant polymers. This aim was one of the reasons for creating high-molecular compounds with chains made up of various atoms (Si, AI, B, Ti, etc.) and oxygen or nitrogen. The production scale of elementorganic compounds, especially elemen- torganic oligomers and polymers, as well as extremely diverse requirements to the materials based on these compounds in different economic spheres (medicine, transportation, agriculture, etc.) and advances in aeroplane and rocket building, microelectronics, radio and electrical engineering pose new problems to elementorganic chemistry. Among these problems are: 1. Expanding the polymer operating temperature range to produce nonmetallic materials (plastics, rubbers, fibres, paint coatings, etc.); 2. Improving mechanical characteristics of synthesised polymers and materials based on them; 3. Improving their physical and chemical inertness (i.e. resistance to weather effects, light, radiation, liquids); 4. Creating the polymers which can be the basis of nonflammable materials with a required set of technical characteristrics. These problems can be successfully solved by finding techniques to synthesise new polymers with a varied molecular structure, by modifying known polymers, as well as by polymer alloying, i.e. adding small amounts of substances with a composition different from that of the polymer. Because high-molecular compounds in the form of various nonmetallic materials are so widely used, especially in crowded places, a serious problem nowadays is to create nonmetallic materials which do not sustain combustion or are totally nonflammable. Polymer heat resistance largely depends on their macromolecular structure, and their thermal-oxidative stability and nonflammability depend on the type and number of the organic groups surrounding the chains. Hence the importance of combining the optimal lattice density in macromolecules with a convenient type and number of lateral organic groups. In this case the greatest effect can be expected from polyorganosiloxanes with a branched (I), ladder (II) and spirocyclic (III) molecular structure, or from polyorganosiloxanes where these structures are combined with methyl and phenyl lateral groups. Methyl groups oxidise easier than phenyl groups, but, if they are replaced by oxygen, the weight loss of the polymer is insignificant. In I and II structure polymers with methyl groups the carbon content does not exceed 8-12%. These polymers have already been used in the technology for obtaining nonflammable fibreglass and asbestos plastics. Polymers with structures II and III are of great interest in the design of heat resistant nonmetallic materials. These blocks can polymerise without emitting volatile matter and, consequently, ensure contact molding of glass and asbestos plastics, whereas copolymers with a combination of structures II and III seem to be able to transform into latticed polymers with cyclic or polycyclic silicone groups in cross-link sites between linear sections. In this case the cross-link sites, depending on the size and structure of the cycle, may be subject to conformational transitions when stressed; consequently, the rigidity of the cross-link sites will be very different from the one typical of latticed polymers. These polymers commonly have carbon atoms in the cross-link sites and are currently studied. At present we distinguish polymers with various structures of the macromolecular chain (Diagram 1). Of particular interest is the study of synthesis reactions of linear polymers, the chains of which consist of flexible linear sections and rigid mono- and polycyclic fragments: more elementorganic compounds in various fields of technology and in households. Most polymers with these molecular chains have already been synthesised in labs, but only few of them have been implemented in industry. Therefore, the nearest and most urgent task of chemical engineers is to unite their efforts with scientists in order to design and implement convenient and accessible technological processes of the synthesis of elementorganic polymers. In the nearest future chemical engineers should pay close attention to the design and implementation of new ways of obtaining elementorganic, silicone and elementosilicone polymers in particular, by finding efficient techniques to synthesise block oligomers (prepolymers) of a given composition and their subsequent transformation into polymers with optimal characteristics. In this case the combination of fragments with flexible and rigid molecular chains in linear chains can help to synthesise elastomers and plastomers with a higher thermostability. To improve mechanical and some other specific properties, one might find interesting the synthesis of comb-shaped polymers with a uni- and bidirectional molecular structure: \K n Wide opportunities for the controlled variation of properties are offered by the synthesis of block copolymers with organo-inorganic main molecular chains, as well as by the synthesis of block copolymers containing besides silicon other elements in the form of various groups (spirotitaniumsiloxane, spiroironsiloxane, phosphonitrilsiloxane, carboransiloxane), which will undoubledly lead to the creation of new technically valuable materials. The results that have been achieved at present still do not meet the demands of our economy in the production scale of elementorganic oligomers and polymers. We need to increase the production pace to use The synthesis of silicone polymers from prepolymers will allow one to obtain not only polyorganosiloxanes, but also polyelementorganosiloxanes of a more regular structure (unlike the existing processes of hydrolytic co-condensation of various organochlorosilanes which form polymers of a static composition). Therefore, the polymers obtained in this way will have improved chemical and physicochemical properties, and materials based on them will have valuable performance characteristics. Moreover, a new technique for obtaining polymers based on block oligomers will help to build harmless and wasteless industries, which is especially important from the ecological point of view. A promising area is the design of modern ceramic and glass ceramic materials based on high purity elementorganic compounds Si(OR)4, Al(OR)3, B(OR)3, etc.), because traditional materials (metals, metal-based alloys, plastics, etc.) do not meet contemporary technical requirements to products designed to operate under extreme conditions. We understand modem ceramics as all strong inorganic materials which are processed at high temperatures and have superior physicochemical and heat resistance characteristics. The range of their application is very wide. For instance, modern ceramics is used as a substrate for catalysts, as well as in the production of ball bearings and various elements for electronic equipment, atomic power plant and thermonuclear fusion equipment. Refractory ceramics is one of the best heat insulators for aircraft, rocket, space technology, etc. Let us give just one example of the advisability and economic feasibility of the use of modern ceramics in turbine and diesel engines instead of doped heat resistant alloys. The use of ceramics in this case helps to increase the operating temperature in the combustion chamber up to 1400-1500°C without any additional cooling of the given products, which reduces the fuel consumption almost twofold.
Glass-ceramic materials can be used to produce elements of fibre optics, translucent ceramics, photochromic and laser glasses, oxide conductive glasses, etc. The advantages of modern ceramic and glass-ceramic materials are realised only if they are produced not by the traditional technique, but using the recent so-called sol-gel technology. One of the most important sol-gel methods is based on the hydrolitic condensation of tetraethoxysilane in the presence of water-soluble metal salts, or on hydrolitic cocondenstation of tetraethoxysilane and alcoxides of aluminum and other metals, followed by hydrolysate gelating and processing the gels at 500-600°C. We should note here that in order to obtain modem ceramics and glass-ceramics, one needs compounds with an exceptionally small amount of foreign impurities, since impurities interfere with obtaining ceramic materials of required quality.
Aerogel possesses excellent heat insulating properties: felt-tip pens lying on Aerogel are protected from the flames below and do not melt. Aerogel, which is 99.9% air and 0.1% silicone-dioxide gel, is subjected to maximum desiccation. This preserves its original size and shape, because normal evaporation can destroy the gel. Of all materials known, Aerogel is the least dense (it is only 3 times denser than air), but is a unique insulator. Its insulating properties are 39 times higher than those of fibreglass plastic; at the same time its density is 1000 times less than that of glass, which alsohas a silicone structure. Aerogel can sustain temperatures up to 1400°C. A man-sized aerogel block, which weighs not more than 400 g, supports up to half a ton of weight.
Aerogel is a special materials with extreme micron porosity. It consists of separate particles of several nanometers, interconnected in a high-porosity branched structure. It was made on the basis of gel consisting of colloid silicone, the structural parts of which are filled with solvents. Aerogel is subjected to high temperature under pressure which rises to the critical point; it is very strong and easily endures stress both at lift-off and in the space environment. This material has already been tried in space by Spacelab II and Eureca shuttles, as well as by the American Mars Pathfinder Rover. The growing amount of research of the application of modern ceramics in various industries, as well as their virtually unlimited possibilities suggest that in the nearest decade these materials will be widely used in various spheres of economy. Recently a lot of interest has been drawn to the synthesis of silicone and other elementorganic highly branched oligomers with a so-called dendrimer structure. Oligomers of this kind are obtained by multistage synthesis. For example, highly branched oligomethylsiloxanes of the given structure are obtained in the following way. The first stage is the reaction between methyltrichlorosilane and sodiumoximethyldiethoxisilane.The second stage is the selective replacement of ethoxyl groups with chlorine atoms using sulfuryl chloride.These reactions yield a second, and then a third "generation" of dendrimers, which will eventually contain 22 silicon atoms. We should also develop the processes of producing filled polymers during their synthesis, which is economically feasible and justifiable. Researchers have already developed a process to obtain filled conductive silicone rubbers by the technique stated above. In the conclusion we should say that the chemistry of synthetic elementorganic polymers is a young science and still has a lot to discover. The possibilities of elementorganic polymer chemistry, and consequently of their production development, are truly unlimited. If originally synthetic polymers appeared as a result of emulating natural compounds and as their substitutes, nowadays we have many polymers which resulted from scientific and engineering creativity and have no counterparts in nature.