4 which applies to inorganic polymeric materials. Germanium and tin polymers

INORGANIC POLYMERS

They have an inorganic main chains and do not contain org. side radicals. The main chains are built from covalent or ionic-covalent bonds; in some N. p. the chain of ionic-covalent bonds can be interrupted by single coordination joints. character. Structural N. p. is carried out according to the same characteristics as org. or elementoorg. polymers (see High molecular weight compounds). Among natural N. p. the most. reticular ones are common and are part of most minerals of the earth's crust. Many of them form a type of diamond or quartz. The upper elements are capable of forming linear n.p. rows III-VI gr. periodic systems. Within groups, as the row number increases, the ability of elements to form homo- or heteroatomic chains decreases sharply. Halogens, as in org. polymers, play the role of chain termination agents, although all possible combinations of them with other elements can form side groups. Elements VIII gr. can be included in the main chain, forming a coordination. N. p. The latter, in principle, are different from org. coordination polymers, where is the coordinate system bonds form only a secondary structure. Mn. or metal salts of variable valency macroscopically. St. you look like mesh N. p.

Long homoatomic chains (with degree of polymerization n >= 100) form only the elements of group VI - S, Se and Te. These chains consist of only backbone atoms and do not contain side groups, but the electronic structures of the carbon chains and the S, Se and Te chains are different. Linear carbon - cumulenes=C=C=C=C= ... and car-bin ChS = SChS = MF... (see Carbon); in addition, carbon forms two-dimensional and three-dimensional covalent crystals, respectively. graphite And diamond. Sulfur and tellurium form atomic chains with simple bonds and very high p. They have the character of a phase transition, and the temperature region of stability of the polymer has a smeared lower and well-defined upper boundary. Below and above these boundaries are stable, respectively. cyclical octamers and diatomic molecules.

Dr. elements, even the closest neighbors of carbon in psriodic. system-B and Si are no longer capable of forming homoatomic chains or cyclic. oligomers with n >= 20 (regardless of the presence or absence of side groups). This is due to the fact that only carbon atoms are capable of forming purely covalent bonds with each other. For this reason, binary heterochain n.p. type [HMPLH] are more common n(see table), where the M and L atoms form ionic-covalent bonds with each other. In principle, heterochain linear chains do not necessarily have to be binary: a regularly repeating section of the chain can. formed by more complex combinations of atoms. The inclusion of metal atoms in the main chain destabilizes the linear structure and sharply reduces i.

COMBINATIONS OF ELEMENTS FORMING BINARY HETEROCYNIC INORGANIC POLYMERS TYPE [HMMHLH] n(MARKED WITH A + SIGN)

* Also forms inorg. polymers of composition [CHVCHRCH] n.

The peculiarities of the electronic structure of the main chains of homo-chain nucleotides make them very vulnerable to attack by nucleophiles. or electroph. agents. For this reason alone, chains containing as a component L or others adjacent to it in periodicity are relatively more stable. system. But these chains usually also need stabilization, in nature. N.P. is associated with the formation of network structures and with a very strong intermolecular. interaction side groups (including the formation of salt bridges), as a result of which the majority of even linear N. items are insoluble and macroscopic. St. you are similar to reticular N. p.

Practical Of interest are linear N. items, which are most common. degrees are similar to organic ones - they can exist in the same phase, aggregate or relaxation states, and form similar supermoles. structures, etc. Such nanoparticles can be heat-resistant rubbers, glasses, fiber-forming materials, etc., and also exhibit a number of properties that are no longer inherent in org. polymers. These include polyphosphazenes, polymeric sulfur oxides (with different side groups), phosphates, . Certain combinations of M and L form chains that have no analogues among org. polymers, e.g. with a wide conduction band and . Having a well-developed flat or space has a wide conduction band. structure. A common superconductor at temperatures near 0 K is the polymer [ЧSNЧ] X; at elevated temperatures, it loses superconductivity, but retains its semiconductor properties. High-temperature superconducting nanoparticles must have a ceramic structure, that is, they must contain oxygen in their composition (in the side groups).

Processing of nitrate into glass, fibers, ceramics, etc. requires melting, and this is usually accompanied by reversible depolymerization. Therefore, modifying agents are usually used to stabilize moderately branched structures in melts.

Lit.: Encyclopedia of Polymers, vol. 2, M., 1974, p. 363-71; Bartenev G.M., Ultra-strong and high-strength inorganic glasses, M., 1974; Korshak V.V., Kozyreva N.M., "Advances in Chemistry", 1979, v. 48, v. 1, p. 5-29; Inorganic polymers, in: Encyclopedia of polymer science and technology, v. 7, N.Y.-L.-Sydney, 1967, p. 664-91. S. Ya. Frenkel.

Chemical encyclopedia. - M.: Soviet Encyclopedia. Ed. I. L. Knunyants. 1988 .

See what "INORGANIC POLYMERS" are in other dictionaries:

Polymers whose molecules have inorganic main chains and do not contain organic side radicals (framing groups). In nature, three-dimensional network inorganic polymers are widespread, which in the form of minerals are part of... ...

Polymers that do not contain C C bonds in the repeating unit, but are capable of containing an organic radical as side substituents. Contents 1 Classification 1.1 Homochain polymers ... Wikipedia

Polymers whose molecules have inorganic main chains and do not contain organic side radicals (framing groups). Three-dimensional network inorganic polymers, which in the form of minerals are part of... ... are widespread in nature. Encyclopedic Dictionary

Polymers with an inorganic (not containing carbon atoms) main chain of a macromolecule (See Macromolecule). Side (framing) groups are usually also inorganic; however, polymers with organic side groups are often also classified as H...

Polymers and macromolecules have inorganic Ch. chains and do not contain organic side chains. radicals (framing groups). Practical synthetic matters. polymer polyphosphonitrile chloride (polydichlorophasphazene) [P(C1)2=N]n. Others are obtained from it... ... Big Encyclopedic Polytechnic Dictionary

Polymers, molecules that have inorganic Ch. chains and do not contain organic. side radicals (framing groups). In nature, three-dimensional reticulated NPs are widespread, which in the form of minerals are included in the composition of the earth's crust (for example, quartz). IN… … Natural science. Encyclopedic Dictionary

- (from poly... and Greek meros share part), substances whose molecules (macromolecules) consist of a large number of repeating units; The molecular weight of polymers can vary from several thousand to many millions. Polymers by origin... Big Encyclopedic Dictionary

Ov; pl. (unit polymer, a; m.). [from Greek polys numerous and meros share, part] High-molecular chemical compounds consisting of homogeneous repeating groups of atoms, widely used in modern technology. Natural, synthetic products... ... Encyclopedic Dictionary

- (from the Greek polymeres consisting of many parts, diverse) chemical compounds with a high molecular weight (from several thousand to many millions), the molecules of which (macromolecules (See Macromolecule)) consist of a large number ... ... Great Soviet Encyclopedia

Classification by method of production (origin)

Flammability classification

Classification by behavior when heated

Classification of polymers according to the structure of macromolecules

CLASSIFICATION OF POLYMERS

Synthesis of polymers.

A polymer is a chemical substance that has a large molecular weight and consists of a large number of periodically repeating fragments linked by chemical bonds. These fragments are called elementary units.

Thus, the characteristics of polymers are as follows: 1. very high molecular weight (tens and hundreds of thousands). 2. chain structure of molecules (usually simple bonds).

It should be noted that polymers today successfully compete with all other materials used by humanity since ancient times.

Application of polymers:

Polymers for biological and medical purposes

Ion and electron exchange materials

Heat and heat resistant plastics

Insulators

Construction and structural materials

Surfactants and materials resistant to aggressive environments.

The rapid expansion of polymer production has led to the fact that their fire hazard (and all of them burn better than wood) has become a national disaster for many countries. When they burn and decompose, various substances are formed, mostly toxic to humans. Knowing the dangerous properties of the resulting substances is necessary to successfully combat them.

Classification of polymers according to the composition of the main chain of macromolecules (the most common):

I. Carbon-chain IUDs - the main polymer chains are built only from carbon atoms

II. Heterochain BMCs - the main polymer chains, in addition to carbon atoms, contain heteroatoms (oxygen, nitrogen, phosphorus, sulfur, etc.)

III. Organoelement polymer compounds - the main chains of macromolecules contain elements that are not part of natural organic compounds (Si, Al, Ti, B, Pb, Sb, Sn, etc.)

Each class is divided into separate groups depending on the structure of the chain, the presence of bonds, the number and nature of substituents, and side chains. Heterochain compounds are classified, in addition, taking into account the nature and number of heteroatoms, and organoelement polymers - depending on the combination of hydrocarbon units with atoms of silicon, titanium, aluminum, etc.

a) polymers with saturated chains: polypropylene – [-CH 2 -CH-] n,

polyethylene – [-CH 2 -CH 2 -] n; CH 3

b) polymers with unsaturated chains: polybutadiene – [-CH 2 -CH=CH-CH 2 -] n;

c) halogen-substituted polymers: Teflon - [-CF 2 -CF 2 -] n, PVC - [-CH 2 -CHCl-] n;

d) polymer alcohols: polyvinyl alcohol – [-CH 2 -CH-] n;

e) polymers of alcohol derivatives: polyvinyl acetate – [-CH 2 -CH-] n;

f) polymeric aldehydes and ketones: polyacrolein – [-CH 2 -CH-] n;

g) polymers of carboxylic acids: polyacrylic acid – [-CH 2 -CH-] n;

h) polymer nitriles: PAN – [-CH 2 -CH-] n;

i) polymers of aromatic hydrocarbons: polystyrene – [-CH 2 -CH-] n.

a) polyethers: polyglycols – [-CH 2 -CH 2 -O-] n;

b) polyesters: polyethylene glycol terephthalate –

[-O-CH 2 -CH 2 -O-C-C 6 H 4 -C-] n;

c) polymer peroxides: polymer styrene peroxide – [-CH 2 -CH-O-O-] n;

2. Polymers containing nitrogen atoms in the main chain:

a) polymer amines: polyethylenediamine – [-CH 2 –CH 2 –NH-] n;

b) polymer amides: polycaprolactam – [-NН-(СH 2) 5 -С-] n;

3. Polymers containing both nitrogen and oxygen atoms in the main chain - polyurethanes: [-С-NН-R-NN-С-О-R-О-] n;

4.Polymers containing sulfur atoms in the main chain:

a) polythioethers [-(CH 2) 4 – S-] n;

b) polytetrasulfides [-(CH 2) 4 -S - S-] n;

5.Polymers containing phosphorus atoms in the main chain

for example: O

[- P – O-CH 2 -CH 2 -O-] n ;

1. Organosilicon polymer compounds

a) polysilane compounds R R

b) polysiloxane compounds

[-Si-O-Si-O-]n;

c) polycarbosilane compounds

[-Si-(-C-) n -Si-(-C-) n -] n ;

d) polycarbosiloxane compounds

[-O-Si-O-(-C-) n -] n ;

2. Organotitanium polymer compounds, for example:

OC 4 H 9 OC ​​4 H 9

[-O – Ti – O – Ti-] n ;

OC 4 H 9 OC ​​4 H 9

3. Organoaluminum polymer compounds, for example:

[-O – Al – O – Al-] n ;

Macromolecules can have a linear, branched and spatial three-dimensional structure.

Linear polymers consist of macromolecules with a linear structure; such macromolecules are a collection of monomer units (-A-) connected into long unbranched chains:

nA ® (…-A - A-…) m + (…- A - A -…) R + …., where (…- A - A -…) are polymer macromolecules with different molecular weights.

Branched polymers are characterized by the presence of side branches in the main chains of macromolecules, shorter than the main chain, but also consisting of repeating monomer units:

…- A – A – A – A – A – A – A- …

Spatial polymers with a three-dimensional structure are characterized by the presence of chains of macromolecules interconnected by forces of basic valencies using cross bridges formed by atoms (-B-) or groups of atoms, for example monomer units (-A-)

A – A – A – A – A – A – A –

A – A – A – A – A – A –

A – A – A – A – A – A -

Three-dimensional polymers with frequent cross-links are called network polymers. For three-dimensional polymers, the concept of a molecule loses its meaning, since in them individual molecules are connected to each other in all directions, forming huge macromolecules.

thermoplastic- polymers of linear or branched structure, the properties of which are reversible with repeated heating and cooling;

thermosetting- some linear and branched polymers, the macromolecules of which, when heated, as a result of chemical interactions occurring between them, are connected to each other; in this case, spatial network structures are formed due to strong chemical bonds. After heating, thermosetting polymers usually become infusible and insoluble - a process of irreversible hardening occurs.

This classification is very approximate, since the ignition and combustion of materials depend not only on the nature of the material, but also on the temperature of the ignition source, ignition conditions, shape of the product or structures, etc.

According to this classification, polymeric materials are divided into flammable, low-flammable and non-flammable. Of the combustible materials, those that are difficult to ignite are distinguished, and those that are difficult to burn are self-extinguishing.

Examples of combustible polymers: polyethylene, polystyrene, polymethyl methacrylate, polyvinyl acetate, epoxy resins, cellulose, etc.

Examples of fire-resistant polymers: PVC, Teflon, phenol-formaldehyde resins, urea-formaldehyde resins.

Natural (proteins, nucleic acids, natural resins) (animal and

plant origin);

Synthetic (polyethylene, polypropylene, etc.);

Artificial (chemical modification of natural polymers - ethers

cellulose).

Inorganic: quartz, silicates, diamond, graphite, corundum, carbine, boron carbide, etc.

Organic: rubbers, cellulose, starch, organic glass and

Polymers are high-molecular compounds consisting of many repeating atomic groups of different or identical structures - units. These links are interconnected by coordination or chemical bonds into branched or long linear chains and into spatial three-dimensional structures.

Polymers are:

• synthetic,
• artificial,
• organic.

Organic polymers are formed in nature in animal and plant organisms. The most important of them are proteins, polysaccharides, nucleic acids, rubber and other natural compounds.

Man has long and widely used organic polymers in his daily life. Leather, wool, cotton, silk, fur - all this is used to produce clothing. Lime, cement, clay, organic glass (plexiglass) - in construction.

Organic polymers are also present in humans. For example, nucleic acids (also called DNA), as well as ribonucleic acids (RNA).

Properties of organic polymers

All organic polymers have special mechanical properties:

• low fragility of crystalline and glassy polymers (organic glass, plastics);
• elasticity, that is, high reversible deformation under small loads (rubber);
• orientation of macromolecules under the influence of a directed mechanical field (production of films and fibers);
• at low concentrations, the viscosity of solutions is high (polymers first swell and then dissolve);
• under the influence of a small amount of reagent they can quickly change their physical and mechanical characteristics (for example, leather tanning, rubber vulcanization).

Table 1. Combustion characteristics of some polymers.

Table 2. Solubility of polymer materials.

Table 3. Coloring of polymers according to the Lieberman-Storch-Moravsky reaction.

Articles on the topic

Among most materials, the most popular and widely known are polymer composite materials (PCMs). They are actively used in almost every area of ​​human activity. It is these materials that are the main component for the manufacture of various products used for completely different purposes, from fishing rods and boat hulls, to cylinders for storing and transporting flammable substances, as well as helicopter rotor blades. Such wide popularity of PCM is associated with the ability to solve technological problems of any complexity associated with the production of composites with certain properties, thanks to the development of polymer chemistry and methods for studying the structure and morphology of polymer matrices that are used in the production of PCM.

There is practically no person in the modern world who does not have at least some idea about polymers. Polymers go through life with a person, making his life more and more convenient and comfortable. When mentioning polymers, the first associations will be with synthetic organic substances, since they are more visible. Natural polymers - natural organic substances - although there are more of them in the world around us, in the associative perception of a person they fade into the background. They always surround us, but no one thinks about the nature of the origin of flora and fauna. Cellulose, starch, lignin, rubber, proteins and nucleic acids are the main materials used by nature to create the animal and plant world around us. And absolutely no one will perceive precious stones, graphite, mica, sand and clay, glass and cement as polymers. Nevertheless, science has established the fact of the polymeric structure of many inorganic compounds, including those listed above. Polymer substances consist of macromolecules. When polymers are formed, a large number of atoms or groups of atoms are bonded to each other by chemical bonds - covalent or coordination. Polymer macromolecules contain tens, hundreds, thousands or tens of thousands of atoms or repeating elementary units. Information about the polymer structure was obtained by studying the properties of solutions, the structure of crystals, and the mechanical and physicochemical properties of inorganic substances. In support of the above, it should be noted that there is a sufficient amount of scientific literature confirming the fact of the polymeric structure of some inorganic substances.

A logical remark would be: why is there so much information about synthetic organic polymers and so little about inorganic ones? If there are inorganic polymeric substances, what exactly are they and where are they used? Several examples of inorganic polymers were given above. These are well-known substances that everyone knows, but few people know that these substances can be classified as polymers. By and large, the average person doesn’t care whether graphite can be classified as a polymer or not; as for precious stones, for some it may even be offensive to equate expensive jewelry with cheap plastic jewelry. Nevertheless, if there is reason to call some inorganic substances polymers, then why not talk about it. Let's look at some representatives of such materials and look in more detail at the most interesting ones.
The synthesis of inorganic polymers most often requires very pure starting materials, as well as high temperatures and pressures. The main methods for their production, like organic polymers, are polymerization, polycondensation and polycoordination. The simplest inorganic polymers include homochain compounds consisting of chains or frameworks built from identical atoms. In addition to the well-known carbon, which is the main element involved in the construction of almost all organic polymers, other elements can also participate in the construction of macromolecules. These elements include boron from the third group, silicon, germanium and tin from the fourth group, which also includes carbon, phosphorus, arsenic, antimony and bismuth from the fifth group, sulfur, selenium, tellurium from the sixth. Mainly homochain polymers obtained from these elements are used in electronics and optics. The electronics industry is developing at a very high pace and the demand for synthetic crystals has long exceeded supply. Of particular note, however, is carbon and the inorganic polymers that are produced on its basis: diamond and graphite. Graphite is a well-known material that has found application in various industries. Pencils, electrodes, crucibles, paints, and lubricants are made from graphite. Thousands of tons of graphite go to the needs of the nuclear industry due to its properties to slow down neutrons. In the article we will dwell in more detail on the most interesting representatives of inorganic polymers - precious stones.
The most interesting, pretentious, and beloved by women representative of inorganic polymers are diamonds. Diamonds are very expensive minerals, which can also be classified as inorganic polymers; they are mined in nature by five large companies: DeBeers, Alrosa, Leviev, BHPBilliton, RioTinto. It was the DeBeers company that created the reputation of these stones. Smart marketing boils down to the slogan, “forever.” DeBeers has turned this stone into a symbol of love, prosperity, power, and success. An interesting fact is that diamonds are found quite often in nature, for example sapphires and rubies, which are rarer minerals, but they are valued lower than diamonds. The most interesting thing is the situation that has developed in the natural diamond market. The fact is that there are technologies that make it possible to obtain synthetic diamonds. In 1954, General Electric researcher Tracy Hall invented a device that made it possible to obtain diamond crystals from iron sulfide at a pressure of 100,000 atmospheres and a temperature of over 2500ºC. The quality of these stones was not high from a jewelry point of view, but the hardness was the same as that of natural stone. Hall's invention was improved and in 1960 General Electric created a plant in which it was possible to produce gem-quality diamonds. The negative point was that the price of synthetic stones was higher than natural ones.
At the moment, there are two technologies for synthesizing diamonds. HPHT (high pressure/high temperature) technology is the synthesis of diamonds in a combination of high pressure and high temperature. CVD (chemical vapor deposition) technology is a chemical vapor deposition technology that is considered more progressive and allows you to grow diamond, as if simulating the natural conditions of its growth. Both technologies have advantages and disadvantages. Campaigns using them solve the shortcomings of technology by using their own inventions and developments. For example, back in 1989, a group of Soviet scientists from Novosibirsk managed to reduce the fusion pressure to 60,000 atmospheres. After the collapse of the Soviet Union, developments in the field of diamond synthesis continued, thanks to many foreign investors interested in obtaining the technology for cheap synthesis of high-quality gemstones. For example, DeBeers, in order not to lose the opportunity to control the market, financed the work of some scientists. Some private entrepreneurs bought diamond synthesis equipment in Russia, for example, the now thriving American company Gemesis began by purchasing a diamond growing installation in Russia in 1996 for $60,000. Now Gemesis produces and sells diamonds of rare colors: yellow and blue, and the difference in price between these and exactly the same natural stones reaches 75%.

Another large company synthesizing diamonds, Apollo Diamond, is improving HPHT technology by synthesizing stones in a gas atmosphere of a certain composition (symbiosis technology of HPHT and CVD). This method brings Apollo Diamond to the market of jewelry stones; at the same time, the quality of synthetic diamonds grown using this technology is very high. It is increasingly difficult for gemotologists to distinguish synthetic stones from natural ones. This requires a complex of analyzes using quite complex and expensive equipment. Apollo Diamond synthetic gem diamonds are almost impossible to distinguish from natural minerals using standard analysis methods.

World diamond production is now 115 million carats or 23 tons per year. Theoretically, this gigantic market could collapse and the reputation of diamonds as precious stones would be lost forever. Monopoly firms invest in stabilizing the situation and controlling the market. For example, expensive marketing campaigns are carried out, patents for artificial diamond manufacturing technologies are purchased so that these technologies are never introduced, certificates and quality passports are issued for branded diamonds confirming their natural origin. But will this hold back the progress of fusion technology?

Having talked about diamonds, we were distracted by the brilliance of the precious stones of the jewelry industry, but we should also point out industrial stones. In this case, most diamond growing enterprises operate primarily for the needs of the electronics and optical industries. The industrial stone market may not be as intriguing as the jewelry market, but it is nonetheless huge. For example, Apollo Diamond's main income is the synthesis of thin diamond disks for semiconductors. By the way, now a diamond synthesis installation with a productivity of about 200 kg of diamonds per month can be purchased for 30 thousand dollars.

Another representative of precious stones is ruby. The first synthetic ruby ​​was born in 1902. It was synthesized by the French engineer Verneuil by melting aluminum oxide and chromium powder, which then crystallized into a six-gram ruby. This simplicity of synthesis allowed the relatively rapid development of industrial production of rubies around the world. This stone is in great demand. Every year about 5 tons of rubies are mined in the world, and market needs amount to hundreds of tons. Rubies are needed in the watch industry and in the production of lasers. The technology proposed by Verneuil subsequently provided the prerequisites for the synthesis of sapphires and garnets. The largest productions of artificial rubies are located in France, Switzerland, Germany, Great Britain, and the USA. The economics of production are as follows. The lion's share of the cost is consumed by energy costs. At the same time, the cost of synthesizing a kilogram of rubies is 60 dollars, the cost of a kilogram of sapphires is 200 dollars. The profitability of such a business is very high, since the purchase price for crystals is at least twice as high. Here a number of factors should be taken into account, such as the fact that the larger the grown single crystal, the lower its cost; also, when producing products from crystals, their price will be much higher than the price of sold crystals (for example, the production and sale of glass). As for equipment, Russian installations for growing crystals cost about 50 thousand dollars, Western ones are an order of magnitude more expensive, while the payback period for organized production is on average two years. As already mentioned, the market needs for synthetic crystals are colossal. For example, sapphire crystals are in great demand. About a thousand tons of sapphires are synthesized around the world per year. Annual production needs reach a million tons!
Emeralds are synthesized exclusively for the needs of the jewelry industry. Unlike other crystals, emerald is obtained not from a melt, but from a solution of boron ahydride at a temperature of 400 ° C and a pressure of 500 atmospheres in a hydrothermal chamber. It is curious that the extraction of natural stone is only 500 kilograms per year. Synthetic emeralds are also produced in the world in quantities that are not as large as other crystals, about a ton per year. The fact is that the technology for synthesizing emeralds is low-productivity, but the profitability of such production is high. Producing about 5 kilograms of crystals per month at a cost of $200 per kilogram, the selling price of synthetic emeralds is almost equal to the price of natural ones. The cost of the installation for the synthesis of emeralds is about 10 thousand dollars.
But the most popular synthetic crystal is silicon. Perhaps it will give odds to any precious stone. At the moment, silicon occupies 80% of the total market for synthetic crystals. The market is experiencing a shortage of silicon due to the rapid development of high technologies. At the moment, the profitability of silicon production exceeds 100%. The price of a kilogram of silicon is about $100 per kilogram, while the cost of synthesis reaches $25.

Ultrapure silicon is used as a semiconductor. Solar photocells with a high efficiency are made from its crystals. Silicon, like carbon, can create long molecular chains from its atoms. In this way, silane and rubber are obtained, which have amazing properties. Several years ago, the whole world was excited by the news of the experiments of the American engineer Walter Robbs, who managed to produce a film of silicone rubber 0.0025 centimeters thick. He covered the cage in which the hamster lived with this rubber and lowered the hamster into the aquarium. For several hours, the world's first submarine hamster breathed oxygen dissolved in water, and was alert and showed no signs of anxiety. It turns out that the film plays the role of a membrane, performing the same functions as the gills of fish. The film allows life gas molecules inside, while carbon dioxide is forced out through the film. This discovery makes it possible to organize human life under water by moving aside cylinders with a breathing mixture and oxygen generators.

Silicon comes in three types: metallurgical silicon (MG), electronics grade silicon (EG), and solar grade silicon (SG). Due to a series of energy crises, alternative energy technologies are being intensively introduced. These include the conversion of solar energy into electrical energy, that is, the use of solar installations powered by solar batteries. An important component of solar cells is silicon. In Ukraine, the Zaporozhye titanium-magnesium plant produced silicon for solar batteries. Under the Soviet Union, this enterprise produced 200 tons of silicon, with the all-Union production volume being 300 tons. The author currently knows nothing about the situation with silicon production in Zaporozhye. The cost of organizing a modern production of polycrystalline silicon for the needs of the energy industry with a capacity of 1000 tons per year is about 56 million dollars. The synthesis of silicon for various needs throughout the world ranks first in demand and will hold this position for a long time.

In the article we examined only some representatives of inorganic polymers. Perhaps many of the things told above were perceived by some with surprise and genuine interest. Someone took a fresh look at the concept of the philosopher's stone; even if it is not gold, it is still possible to obtain precious stones from nondescript metal oxides and other unremarkable substances. We hope that the article gave rise to thought and at least entertained the reader with interesting facts.

In nature, there are organoelement, organic and inorganic polymers. Inorganic materials include materials whose main chain is inorganic and whose side branches are not hydrocarbon radicals. Elements of groups III-VI of the periodic system of chemical elements are most prone to the formation of polymers of inorganic origin.

Classification

Organic and inorganic polymers are being actively studied, their new characteristics are being determined, so a clear classification of these materials has not yet been developed. However, certain groups of polymers can be distinguished.

Depending on the structure:

• linear;
• flat;
• branched;
• polymer meshes;
• three-dimensional and others.

Depending on the main chain atoms forming the polymer:

• homochain type (-M-)n - consist of one type of atom;
• heterochain type (-M-L-)n - consist of different types of atoms.

Depending on origin:

• natural;
• artificial.

To classify substances that are macromolecules in the solid state as inorganic polymers, it is also necessary to have a certain anisotropy in their spatial structure and corresponding properties.

Main Features

More common are heterochain polymers, in which there is an alternation of electropositive and electronegative atoms, for example B and N, P and N, Si and O. Heterochain inorganic polymers (HP) can be obtained using polycondensation reactions. The polycondensation of oxoanions is accelerated in an acidic environment, and the polycondensation of hydrated cations is accelerated in an alkaline environment. Polycondensation can be carried out either in solution or at high temperature.

Many of the heterochain inorganic polymers can only be obtained under high-temperature synthesis conditions, for example, directly from simple substances. The formation of carbides, which are polymer bodies, occurs when certain oxides interact with carbon, as well as in the presence of high temperature.

Long homochain chains (with a degree of polymerization n>100) form carbon and p-elements of group VI: sulfur, selenium, tellurium.

Inorganic polymers: examples and applications

The specificity of NP is the formation of polymer macromolecules with a regular three-dimensional structure. The presence of a rigid framework of chemical bonds provides such compounds with significant hardness.

This property allows the use of inorganic polymers. The use of these materials has found wide application in industry.

The exceptional chemical and thermal resistance of NP is also a valuable property. For example, reinforcing fibers made from organic polymers are stable in air up to a temperature of 150-220 °C. Meanwhile, boron fiber and its derivatives remain stable up to a temperature of 650˚C. This is why inorganic polymers are promising for creating new chemically and heat-resistant materials.

NPs, which at the same time have properties similar to organic ones and retain their specific properties, are also of practical importance. These include phosphates, polyphosphazenes, silicates, polymers with various side groups.

Carbon polymers

The task: “Give examples of inorganic polymers” is often found in chemistry textbooks. It is advisable to carry it out with mention of the most prominent NPs - carbon derivatives. After all, this includes materials with unique characteristics: diamonds, graphite and carbine.

Carbyne is an artificially created, little-studied linear polymer with unsurpassed strength indicators, not inferior to, and according to a number of studies, superior to graphene. However, carbyne is a mysterious substance. After all, not all scientists recognize its existence as an independent material.

Externally it looks like a metal-crystalline black powder. Has semiconductor properties. The electrical conductivity of carbyne increases significantly when exposed to light. It does not lose these properties even at temperatures up to 5000 °C, which is much higher than for other materials of similar purpose. The material was obtained in the 60s by V.V. Korshak, A.M. Sladkov, V.I. Kasatochkin and Yu.P. Kudryavtsev by catalytic oxidation of acetylene. The most difficult thing was to determine the type of bonds between carbon atoms. Subsequently, a substance with only double bonds between carbon atoms was obtained at the Institute of Organoelement Compounds of the USSR Academy of Sciences. The new compound was named polycumulene.

Graphite - in this ordering extends only in the plane. Its layers are connected not by chemical bonds, but by weak intermolecular interactions, so it conducts heat and current and does not transmit light. Graphite and its derivatives are fairly common inorganic polymers. Examples of their use: from pencils to the nuclear industry. By oxidizing graphite, intermediate oxidation products can be obtained.

Diamond - its properties are fundamentally different. Diamond is a spatial (three-dimensional) polymer. All carbon atoms are held together by strong covalent bonds. Therefore, this polymer is extremely durable. Diamond does not conduct current or heat and has a transparent structure.

Boron polymers

If you are asked what inorganic polymers you know, feel free to answer - boron polymers (-BR-). This is a fairly extensive class of NPs, widely used in industry and science.

Boron carbide - its formula more correctly looks like this (B12C3)n. Its unit cell is rhombohedral. The framework is formed by twelve covalently bonded boron atoms. And in the middle of it is a linear group of three covalently bonded carbon atoms. The result is a very durable structure.

Borides - their crystals are formed similar to the carbide described above. The most stable of them is HfB2, which melts only at a temperature of 3250 °C. TaB2 has the greatest chemical resistance - it is not affected by either acids or their mixtures.

Boron nitride - it is often called white talc due to its similarity. This similarity is really only superficial. Structurally it is similar to graphite. It is obtained by heating boron or its oxide in an ammonia atmosphere.

Borazon

Elbor, borazon, cyborite, kingsongite, cubonite are superhard inorganic polymers. Examples of their application: production of abrasive materials, metal processing. These are chemically inert substances based on boron. Hardness is closer to that of other materials than diamonds. In particular, borazone leaves scratches on diamond, which also leaves scratches on borazone crystals.

However, these NPs have several advantages over natural diamonds: they have greater heat resistance (withstand temperatures up to 2000 °C, while diamond is destroyed at temperatures in the range of 700-800 °C) and high resistance to mechanical loads (they are not so fragile). Borazon was obtained at a temperature of 1350 °C and a pressure of 62,000 atmospheres by Robert Wentorf in 1957. Similar materials were obtained by Leningrad scientists in 1963.

Inorganic sulfur polymers

Homopolymer - this modification of sulfur has a linear molecule. The substance is not stable; when temperature fluctuates, it breaks up into octahedral cycles. Formed in the event of sudden cooling of molten sulfur.

Polymer modification of sulfur dioxide. Very similar to asbestos, has a fibrous structure.

Selenium polymers

Gray selenium is a polymer with helical linear macromolecules nested in parallel. In the chains, selenium atoms are linked covalently, and macromolecules are linked by molecular bonds. Even molten or dissolved selenium does not break down into individual atoms.

Red or amorphous selenium is also a polymer with a chain structure, but with a poorly ordered structure. In the temperature range of 70-90 ˚С it acquires rubber-like properties, turning into a highly elastic state, which is reminiscent of organic polymers.

Selenium carbide, or rock crystal. Thermally and chemically stable, fairly strong spatial crystal. Piezoelectric and semiconductor. It was obtained under artificial conditions by reacting coal in an electric furnace at a temperature of about 2000 °C.

Other selenium polymers:

• Monoclinic selenium is more ordered than amorphous red, but inferior to gray.
• Selenium dioxide, or (SiO2)n, is a three-dimensional network polymer.
• Asbestos is a polymer of selenium oxide with a fibrous structure.

Phosphorus polymers

There are many modifications of phosphorus: white, red, black, brown, purple. Red - NP of fine-crystalline structure. It is obtained by heating white phosphorus without air access at a temperature of 2500 ˚C. Black phosphorus was obtained by P. Bridgman under the following conditions: pressure of 200,000 atmospheres at a temperature of 200 °C.

Phosphornitride chlorides are compounds of phosphorus with nitrogen and chlorine. The properties of these substances change with increasing mass. Namely, their solubility in organic substances decreases. When the molecular weight of the polymer reaches several thousand units, a rubber-like substance is formed. It is the only sufficiently heat-resistant carbon-free rubber. It is destroyed only at temperatures above 350 °C.

Conclusion

Inorganic polymers for the most part are substances with unique characteristics. They are used in production, in construction, for the development of innovative and even revolutionary materials. As the properties of known NPs are studied and new ones are created, the scope of their application is expanding.