hydrophobic substances. What are hydrophobic substances? Hydrophilic and hydrophobic materials

State educational institution of higher professional education

Ministry of Health of the Russian Federation

(GBOU VPO NSMU of the Ministry of Health of Russia)

Department of Medical Chemistry

Essay

HYDROPHILIC, HYDROPHOBIC, AMPHIPHIC SUBSTANCES: IN NATURE AND IN THE HUMAN BODY.

(literature review)

Completed:

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Introduction

Water is one of the most common substances on earth. It covers most of the earth's surface. Almost all living things are made up primarily of water. In humans, the water content in organs and tissues varies from 20% (in bone tissue) to 85% (in the brain). About 2/3 of the mass of a person is water, in the body of a jellyfish up to 95% of water, even in dry plant seeds, water is 10-12%.

Water has some unique properties. These properties are so important for living organisms that it is impossible to imagine life without this combination of hydrogen and oxygen.

In relation to water, all substances are divided into two groups: hydrophilic - “loving water” and hydrophobic - “afraid of water” (from the Greek “hydro” - water, “phileo” - love and “phobos” - fear). The properties of these substances, as well as their significance in nature, will be discussed in our work.

Hydrophilic and hydrophobic substances

Hydrophilic substances (Greek “hydro” - water, “phileo” - love) are substances whose energy of attraction to water molecules exceeds the energy of hydrogen bonds (the energy of attraction between water molecules), therefore many hydrophilic substances are highly soluble in water.

Hydrophilic substances interact intensively with water molecules. Hydrophilicity is characterized by the magnitude of the adsorption bond of substances with water molecules, the formation of indefinite compounds with them, and the distribution of the amount of water according to the magnitude of the bond energy. The hydrophilicity is mainly determined by the binding energy of the adsorption monolayer, since the subsequent layers are much weaker bound to the substance. Hydrophilicity can be expressed by the heat of adsorption of water vapor or the heat of wetting, as well as the work of wetting a unit surface of the island.

Hydrophobic substances (Greek "hydro" - water, "phobos" - fear) - substances whose energy of attraction of molecules to water molecules is less than the energy of hydrogen bonds of water molecules. Hydrophobic substances include fats, some carbohydrates (starch, glycogen, fiber), nucleic acids, ATP, most proteins that are insoluble in water.

There are no absolutely hydrophobic ("water-repellent") substances; even the most hydrophobic - hydrocarbon and fluorocarbon - surfaces adsorb water. Therefore, hydrophobicity is considered as a small degree of hydrophilicity.

G. and g. can be estimated, as well as the wettability of the surface by water (in air), by the value of the wetting angle q: for hydrophilic surfaces<90° (для абсолютно гидрофильных поверхностей q=0); для гидрофобных поверхностей 90°< <180° (напр., для парафина 105°). На трёхфазной границе твёрдого тела с водой и углеводородной жидкостью при <90° (в водной фазе) поверхность олеофобна, т.е. не смачивается маслом, а при =180° - предельно олеофильна.

Hydrophilic are substances with polar chem. bonds: halides, oxides and their hydrates, carbonates, sulfates, phosphates, silicates and aluminosilicates (clays, glasses), as well as cell membranes. Clean surfaces of metals, carbon, semiconductors, substances consisting of weakly polar molecules, plant leaves, animal skin, insect chitin cover are hydrophobic. All polar groups that make up the molecules of surfactants - surfactants - COOH, -NH2, -SO3Na, etc., are hydrophilic; the hydrocarbon radicals associated with them are hydrophobic.

Amphiphilic substances

Amphiphilicity is a property of molecules of substances (usually organic) that have both hydrophilic and hydrophobic properties. Molecules of amphiphilic compounds are similar to a tadpole: they consist of a long hydrocarbon tail (usually built of more than ten CH2 groups), which ensures solubility in non-polar media, and a polar head, which is responsible for hydrophilic properties. Thus, amphiphilic compounds simultaneously "love" both water (that is, they are hydrophilic) and non-polar solvents (show hydrophobic properties).

Depending on the type of hydrophilic group, amphiphilic compounds bearing a charged cationic or anionic functional group and amphiphilic compounds with an uncharged functional group are isolated. The vast majority of known organic compounds carry more than one charged functional group. An example of such substances are macromolecular compounds - proteins, lipoproteins, block copolymers, etc. The presence of a tertiary structure in protein molecules, which is formed as a result of intramolecular interactions of functional groups (polar or nonpolar) with each other, in itself demonstrates the amphiphilic nature of these compounds.

Another example of amphiphilic compounds is most drugs, the molecules of which combine a set of certain functional groups necessary for effective binding to the target receptor.

Amphiphilic compounds play a special role in wildlife. No animal or plant can exist without them. It is from amphiphilic molecules that the cell membrane consists, which separates the living organism from the hostile external environment. It is these molecules that make up the internal organelles of the cell, participate in the process of its division, and are involved in the metabolism with the environment. Amphiphilic molecules serve as food for us and are formed in our bodies, participate in the internal regulation and cycle of bile acids. Our body contains more than 10% amphiphilic molecules. That is why synthetic surfactants can be dangerous for living organisms and, for example, can dissolve the cell membrane and lead to its death.

Conclusion

In nature, both types of substances are important. You can find a lot of evidence that hydrophobic substances are found almost everywhere. Thus, clean surfaces of metals, semiconductors, as well as animal skin, plant leaves, insect chitin cover have similar properties. In turn, hydrophiles are used in the transport of nutrients in the organisms of animals and plants, the end products of metabolism are also excreted using solutions of biological fluids. Non-polar substances are of great importance in the formation of cell membranes with selective permeability. That is why such properties play an important role in the course of biological processes. In recent years, scientists have been developing more and more new hydrophobic substances with which it is possible to protect various materials from wetting and contamination, thus creating even self-cleaning surfaces. Clothing, metal products, building materials, automotive glass - there are many areas of application. Further study of this topic will lead to the development of multiphobic substances that will become the basis for dirt-repellent surfaces. By creating such materials, people can save time, money and resources, and it will also be possible to reduce the degree of pollution of nature with cleaning products. So further developments will benefit everyone.

Bibliography

1. http://fb.ru/article/133638/chto-takoe-gidrofobnyie-veschestva

2.http://www.schoolhels.fi/school/school_today/dostigeniya/2012_2013/ nanotexnologiya/page6.htm

3.http://pobiologiya.rf/ Biological-dictionary/G/265- Hydrophobic-substances

hydrophilic substances

Hydrophilic matters (substances)

Solids that have the property of being wetted by water. Not wetted by oily liquids.

Brief electronic reference book on the main oil and gas terms with a system of cross-references. - M.: Russian State University of Oil and Gas. I. M. Gubkina. M.A. Mokhov, L.V. Igrevsky, E.S. Novik. 2004 .

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hydrophobic substances

Hydrophobic matters (substances)

Solids that are not wetted by water. Wet with oily liquids.

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The term hydrophilicity (derived from the ancient Greek words "water" and "love") is a characteristic of the intensity of the interaction of a substance with water at the molecular level, that is, the ability of the material to absorb moisture intensively, as well as the high wettability of water by the surface of the substance. This concept can be attributed both to solids, as a property of the surface, and to individual ions, atoms, molecules and their groups.

Hydrophilicity characterizes the value of the bond of adsorption water molecules with the molecules of a substance; in this case, compounds are formed in which the amount of water is distributed according to the values of the binding energy.

Hydrophilicity is inherent in substances that have ionic crystal lattices (hydroxides, oxides, sulfates, silicates, clays, phosphates, glasses, etc.), having polar groups -OH, -NO 2, -COOH, etc. hydrophilicity and hydrophobicity- special cases of interaction of substances with solvents (lyophilicity, lyophobicity).

Hydrophobicity can be considered as a small degree of hydrophilicity, because the action of intermolecular forces of attraction will always be more or less present between the molecules of any body and water. Hydrophilicity and hydrophobicity can be distinguished by how a drop of water spreads on a body with a smooth surface. The drop will spread completely on the hydrophilic surface, and partially on the hydrophobic one, while the value of the angle formed between the surface of the wetted material and the drop is affected by the degree of hydrophobicity of the given body. Hydrophilic substances are substances in which the strength of molecular (ionic, atomic) interactions is quite large. Hydrophobic are metals that are devoid of oxide films, organic compounds that have hydrocarbon groups in the molecule (waxes, fats, paraffins, some plastics), graphite, sulfur and other substances that have weak interaction at the intermolecular level.

The concepts of hydrophilicity and hydrophobicity are applied both to bodies and their surfaces, and to single molecules or individual parts of molecules. For example, the molecules of surface active substances contain polar (hydrophilic) and hydrocarbon (hydrophobic) compounds. The hydrophilicity of the surface part of the body can change dramatically due to the adsorption of such substances.

Hydrophilization is the process of increasing hydrophilicity, and hydrophobization is the process of reducing it. These phenomena are of great importance in the cosmetic industry, in textile technology for the hydrophilization of fabrics (fibers) to improve the quality of washing, bleaching, dyeing, etc.

Hydrophilicity in cosmetics

The perfume and cosmetics industry produces hydrophilic creams and gels that protect the skin from impurities that are insoluble in water. These products contain hydrophilic components that form a film that prevents the penetration of water-insoluble pollutants into the surface layer of the skin.

Hydrophilic creams are made from an emulsion that is stabilized with suitable emulsifiers or with a water-oil-water, oil-water base. In addition, these include dispersed colloidal systems in which hydrophilic surface-active components are stabilized and consisting of water-dispersed or water-glycol mixed solvents of higher fatty acids or alcohols.

Hydrogels (hydrophilic gels) are prepared from bases consisting of water, a mixed non-aqueous or hydrophilic solvent (ethyl alcohol, propylene glycol, glycerin) and a hydrophilic gelling agent (cellulose derivatives, carbomers).

Hydrophilic properties of creams and gels:

quickly and well absorbed;

nourish the skin

after their application does not leave a feeling of greasy;

· cleanse the skin;

firming effect on the skin;

reduce the effect of negative environmental factors;

help the skin maintain its natural ability to regenerate.

Hydrophilic creams and gels are designed to protect the skin when working with water-immiscible oils, fuel oil, petroleum, paints, resins, graphite, soot, organic solvents, cooling lubricants, building foam and numerous other mildly aggressive substances. They are also indispensable when repairing a car, repairing an apartment, during construction, in a country house when working with fertilizers and soil.

The company "KorolevPharm" produces various types of perfumery and cosmetic products, including hydrophilic and hydrophobic creams. The enterprise is a contract manufacturer and carries out all stages of production: formulation development, certification, production start-up, serial production. The production site is equipped with modern equipment.

The enterprise is certified for compliance with the requirements

Some people at school were lucky in chemistry class not only to write boring tests and calculate molar mass or indicate valency, but also to watch how the teacher conducts experiments. Invariably, as part of the experiment, as if by magic, the liquids in the test tubes changed color unpredictably, and something else could explode or burn beautifully. Perhaps not so spectacular, but still interesting experiments in which hydrophilic and hydrophobic substances are used. By the way, what is it and why are they curious?

Physical Properties

In chemistry lessons, going through the next element from the periodic table, as well as all the basic substances, we necessarily talked about their various characteristics. In particular, their physical properties were touched upon: density, under normal conditions, melting and boiling points, hardness, color, electrical conductivity, thermal conductivity, and many others. Sometimes there was talk about such characteristics as hydrophobicity or hydrophilicity, but as a rule, they do not talk about this separately. Meanwhile, this is a rather interesting group of substances that can be easily encountered in everyday life. So it would be useful to learn more about them.

hydrophobic substances

Examples can easily be taken from life. So, you can not mix water with oil - everyone knows this. It simply does not dissolve, but remains floating as bubbles or a film on the surface, since its density is less. But why is this and what other hydrophobic substances exist?

Usually this group includes fats, some proteins and silicones. The name of the substances comes from the Greek words hydor - water and phobos - fear, but this does not mean that the molecules are afraid. It's just that they are little or completely insoluble, they are also called non-polar. There is no absolute hydrophobicity, even those substances that, it would seem, do not interact with water at all, still adsorb it, albeit in negligible amounts. In practice, the contact of such a material with H 2 O looks like a film or droplets, or the liquid remains on the surface and takes the form of a ball, since it has the smallest surface area and provides minimal contact.

Hydrophobic properties are attributed to certain substances. This is due to the low rate of attraction to how it happens, for example, with hydrocarbons.

hydrophilic substances

The name of this group, as you might guess, also comes from Greek words. But in this case, the second part of philia is love, and this perfectly characterizes the relationship of such substances with water - complete "mutual understanding" and excellent solubility. This group, sometimes called "polar", includes simple alcohols, sugars, amino acids, etc. Accordingly, they have such characteristics, since they have a high energy of attraction to the water molecule. Strictly speaking, in general, all substances are hydrophilic to a greater or lesser extent.

Amphiphilicity

But is it possible that hydrophobic substances can simultaneously have hydrophilic properties? It turns out yes! This group of substances is called diphilic, or amphiphilic. It turns out that the same molecule can have in its structure both soluble - polar, and water-repellent - non-polar elements. Such properties, for example, have some proteins, lipids, surfactants, polymers and peptides. When interacting with water, they form various supramolecular structures: monolayers, liposomes, micelles, bilayer membranes, vesicles, etc. In this case, polar groups turn out to be oriented towards the liquid.

Meaning and application in life

In addition to the interaction of water and oil, one can find a lot of evidence that hydrophobic substances are found almost everywhere. Thus, clean surfaces of metals, semiconductors, as well as animal skin, plant leaves, insect chitin cover have similar properties.

In nature, both types of substances are important. Thus, hydrophiles are used in transport in the organisms of animals and plants, the end products of metabolism are also excreted using solutions of biological fluids. Non-polar substances are of great importance in the formation of cell membranes, which are why such properties play an important role in the course of biological processes.

In recent years, scientists have been developing more and more new hydrophobic substances with which it is possible to protect various materials from wetting and contamination, thus creating even self-cleaning surfaces. Clothing, metal products, building materials, automotive glass - there are many areas of application. Further study of this topic will lead to the development of multiphobic substances that will become the basis for dirt-repellent surfaces. By creating such materials, people can save time, money and resources, and it will also be possible to reduce the degree of cleaning products. So further developments will benefit everyone.