The use of non-ionic surfactants. Surfactants: general information. See what "Surfactant" is in other dictionaries

Surfactants (surfactants) are chemical substances, which are able to concentrate at the phase boundaries and reduce the surface (interfacial) tension. Surfactants are used in pharmaceutical and cosmetic products, in the production of shampoos and foaming agents.

Chemical structure of surfactants

A surfactant molecule consists of a hydrophobic hydrocarbon radical and a hydrophilic polar (functional) group, i.e. the molecule is amphiphilic, as a result of which it has a high adsorption capacity. For example, in a water/oil emulsion, at the phase boundary, the hydrophilic group of the surfactant molecule is oriented towards water, and the hydrocarbon part is towards oil. At the same time, the interfacial tension decreases, which ensures the stabilization of oil droplets in water.

A different effect of sugar esters was observed between Gram-positive and Gram-negative bacteria. In general, the antimicrobial activity of sugar esters against Gram-positive bacteria was greater than that of Gram-negative bacteria and fungus. The Gram-negative bacterium was resistant to the inhibitory effects of sugar esters. The degree of esterification of lauroyl sucrose is critical for antimicrobial activity. Several researchers have indicated that di- and triesters do not exhibit antimicrobial activity, probably due to their low water solubility.

The detergent action of surfactants is based on the fact that the surface-active ingredients of lotions, shampoos, soaps are adsorbed on the surface of such contaminants as fat and solid particles, envelop and facilitate their transfer into the washing solution. Surfactants facilitate the spreading of water or products based on them over the skin surface by reducing interfacial tension.

The antimicrobial test of sugar esters reflected the relationship between molecular structure and antibacterial activity. Chain duration fatty acids had a significant effect on antibacterial activity. For example, sucrose monoesters have the same hydrophilic group but different hydrophobic groups.

Surfactants: harm and benefit

Generally, the α-configuration compound is more efficient than the β-configuration for the same carbohydrate, which was similar to our result. Foaming, foaming stability, oily water emulsifying power, and monoester emulsion stability were measured. The results showed that surface properties are influenced by carbon chain length, degree of esterification and hydrophilic groups. Laurate monoesters showed best properties as a surfactant.

Types of Surfactants

The classification of surfactants is based on the division, depending on the nature of the polar group: non-ionic, which do not dissociate into ions in water, and ionic, which, depending on the charge formed during dissociation in water, are divided into: anionic, cationic, amphoteric.

Anionic surfactants, when dissolved in water, form negatively charged ions with a long hydrocarbon chain (organic anions) and an ordinary cation. Anionic surfactant emulsifiers are very effective:

The antimicrobial activity was also affected by the length of the carbon chain, the degree of esterification and hydrophilic groups. For disaccharide fatty acid monoesters middle length fatty acid chain length is the most important factor affecting surface activity and antimicrobial activity, while saccharide groups and degree of esterification are less important.

Soaps emulsify lipoid secretions from the skin and remove, along with most of the accompanying dirt, desquamated epithelium and bacteria, which are then washed off with foam. The antibacterial activity of soaps is often enhanced by the inclusion of certain antiseptics, such as hexachlorophene, phenols, carbanilides, or potassium iodide. They are incompatible with cationic surfactants.

when creating oil/water emulsions;
when dispersing a number of powdered materials;
when used in foam detergents for high foaming in hard water.

An example of an anionic surfactant that is often used in cosmetic formulations such as detergents is sodium lauryl ethoxysulfate (INCI nomenclature "Sodium Laureth Sulfate"). It is obtained by sulfation of saturated or unsaturated primary higher alcohols, followed by neutralization with sodium hydroxide, ammonia or triethanolamine. It is often produced in the form of a pasty mass containing up to 70% of the main substance.

Cationic detergents are a group of alkyl- or aryl-substituted quaternary ammonium compounds with an ionizable halogen such as bromide, iodide or chloride. The main site of action for these compounds appears to be the cell membrane, where they are adsorbed and cause changes in permeability. The activity of old quaternary ammonium compounds is restored by solid water and porous or fibrous materials that adsorb them. They are also inactivated by anionic substances.

The impact of surfactants on the environment

Therefore, they are of limited value in the presence of clogging of the blood and tissues. However, the new dialkyl quaternary ammonium compounds are expected to remain active in hard water and are tolerant of anionic residues. Quaternaries are fourth-generation blends with second generation and exhibit greater biocidal activity under high soil loading conditions, making them useful. disinfectants in barns and feet. Quaternary ammonium compounds are effective against most bacteria, enveloped viruses, some fungi and protozoa, but not against non-indexed viruses, mycobacteria and spores.

Cationic surfactants, when dissolved in water, form positively charged ions (organic cations) and a low molecular weight anion. Cationic surfactants include salts of fatty amines and quaternary ammonium bases. Cationic emulsifiers are less effective than anionic emulsifiers because they reduce surface tension less. But they exhibit bactericidal activity by interacting with cellular proteins of bacteria. Cationic surfactants are actively used in hair care products (shampoos, conditioners, hair conditioners). Aliphatic cationic surfactants with one and two hydrocarbon tails are good antistatic agents and are used in hair cosmetics.

When applied to the skin, they can form a film under which microorganisms can survive, limiting their reliability as antiseptics. Okitendine dihydrochloride is a cationic surfactant that is increasingly being used in Europe as an alternative to quaternary, chlorhexidine and iodophoresis for skin, mucosal and wound antisepsis.

These surfactants can be used to solve many common formulation problems and offer great advantages in various applications thanks to their unique combination of performance characteristics.

Amphoteric surfactants, depending on the pH of the medium, behave in alkaline environment as anionic or in an acidic environment as cationic. Their molecules contain functional groups that can have both negative and positive charges. Such surfactants are well compatible with cationic and anionic ones. Amphoteric surfactants are dermatologically gentle on the skin, which is why they are often used in “no tears” baby shampoos and products for sensitive skin. So, for example, in combination with an anionic surfactant sodium lauryl sulfate, almost completely soften its dermatological rigidity. Amphoteric surfactants have good foaming properties.

What is a surface active agent?

A surfactant is a special substance. It reduces the surface tension of the liquid and increases its spreading and wetting properties. By wetting hydrophobic surfaces, you can disperse them in the composition on water based. This means that it mobilizes and combines materials such as organic pigments, solvents, binders and water, which would otherwise not mix due to their chemical properties.

It contains two hydrophilic and at least two hydrophobic moieties in one molecule, making it a more dynamic surfactant than comparable surfactants with only one hydrophilic or hydrophobic moiety. Non-ionic, so it can be used in anionic or cationic binder systems. Good wetting ability due to low surface tension migration due to multi-hydrophilic components. Good defoaming effect unlike standard non-ionic surfactants such as alcohol ethoxylates has no cloud point as the molecule does not form any micelles giving a clear solution at any temperature prevents re-agglomeration due to its dispersing properties. The production of paints, the production of pigments and dispersions, textiles and cements are also part of this wide range of uses.

Betaines are one of the varieties of amphoteric surfactants. They belong to soft and high-foam surfactants. The amphoteric surfactant cocamidopropyl betaine (Dehiton / Betadet) is included in the composition of cosmetics in the production of shampoos, gels and cream gels, liquid soap, cleansing bath foams. This surfactant contributes to the compatibility of the cosmetic product with the skin, while improving the viscosity and foaming of this product. Thus, Dechiton, especially in children's foaming products, is an emollient component and contributes to the safety of using a detergent.

Download our decision sheet with standard blends and product specifications. Custom blends with different solvents and different percentages can be provided and are available upon request. Contact our specialist Henry van der Meer for more information. Like surfactants, surfactants are the main cleaning agents in soaps and detergents. These agents are added to wash water to reduce its surface tension, thereby increasing the wetting and spreading properties of the water.

Non-ionic (non-ionic) surfactants are surfactants that do not form ions when dissolved in water. They, in comparison with anionic ones, having a weaker foaming ability, have a milder effect on the skin. Such surfactants are often used as emulsifiers, dispersants, solubilizers, as well as co-surfactants, foam stabilizers, wetting agents, etc. Fatty acid diethanolamides can be cited as an example of a nonionic surfactant. They are used in the production of shampoos and foaming detergents in an amount of up to 3% as a refatting agent, foam stabilizer and thickener.

Surfactants are usually organic compounds, which are amphiphilic, meaning that they are soluble in both organic solvents and water. Surface active agents have two parts, one is hydrophilic and the other is hydrophobic. Surface active molecules concentrate at the contact areas or interfaces between oil and water. One end of the molecule is looking for oil, and the other end is looking for water. When water and oil interact, surfactants emulsify the oil and mix it with the liquid in the same way that fat is mixed in milk.

In Russian-made shampoos to achieve the necessary consumer properties and quality improvement, various combinations of surfactants are used depending on the purpose of the cosmetic product.

Surfactants used in the cosmetic industry must comply with the Unified Sanitary and Epidemiological and hygiene requirements to goods subject to sanitary and epidemiological supervision (control).

At the water boundary, these agents capture air molecules to produce foam. By reducing the surface tension of water, surfactants improve cleaning efficiency by allowing the solution to wet the surface quickly and effectively, and therefore the soil can be easily loosened and removed. Surfactants also emulsify oily soils and keep them suspended and dispersed so they don't settle to the surface. To achieve excellent cleaning performance, most cleaners contain two or more surfactants.

Benefits of using surfactants:

lead to the stabilization of the dispersed system, make it impossible for the particles of the dispersed phase to stick together and coagulate;
facilitate the process of dispersion and obtaining cosmetic compositions;
improve the wettability and spreadability of cosmetic substances on the skin;
provide stability of reverse emulsions;
as part of foaming detergents, they improve their foaming and increase the stability of the foam during use.

Literature

Types of surface active agents

Anionic surfactants Nonionic surfactants Cationic surfactants Amphoteric surfactants. Self-assembly is the tendency of surfactant molecules to organize and coordinate into extended structures in water. The process involves the formation of micelles, liquid crystals, and bilayers, which are formed when the hydrophobic tails of surfactant molecules combine together to form small aggregates such as micelles or large layer structures such as cell wall-like bilayers.

Surfactants and compositions. Directory. Edited by M.Yu. Pletnev 2002. - p.40-44.

Fundamentals of cosmetic chemistry. Basic provisions and modern ingredients. Ed. Puchkova T.V. 2011, pp.122-133.

Explanatory Dictionary of Cosmetics and Perfumes v.1 Finished products 2nd ed. 2004. p.20.

Surfactants have a polar (asymmetric) molecular structure, are able to adsorb at the interface between two media and reduce the free surface energy of the system. Quite minor additions of surfactants can change the surface properties of the particles and give the material new qualities. The action of surfactants is based on the phenomenon of adsorption, which simultaneously leads to one or two opposite effects: a decrease in the interaction between particles and stabilization of the interface between them due to the formation of an interfacial layer. Most surfactants are characterized by a linear structure of molecules, the length of which significantly exceeds the transverse dimensions (Fig. 15). Molecular radicals consist of groups that are related in their properties to solvent molecules, and of functional groups with properties that are sharply different from them. These are polar hydrophilic groups, having pronounced valence bonds and having a certain effect on wetting, lubricating and other actions associated with the concept of surface activity . In this case, the stock of free energy decreases with the release of heat as a result of adsorption. Hydrophilic groups at the ends of non-polar hydrocarbon chains can be hydroxyl - OH, carboxyl - COOH, amino - NH 2, sulfo - SO and other strongly interacting groups. Functional groups are hydrophobic hydrocarbon radicals characterized by secondary valence bonds. Hydrophobic interactions exist independently of intermolecular forces, being an additional factor contributing to the convergence, "sticking together" of non-polar groups or molecules. The adsorption monomolecular layer of surfactant molecules is oriented by the free ends of hydrocarbon chains from

These characteristics of surfactants make them an interesting study and research area. Surfactants can also be arranged to form micelles, which allows the hydrophobic tails to get out of the water, however it still allows the hydrophilic heads to remain in the water. Typically, several tens to several hundreds of surfactant molecules per micelle.

See what "Surfactant" is in other dictionaries

When micelles form in water, their tails form a core that can encapsulate an oil droplet, and their heads form an outer shell that maintains favorable contact with water. When surfactants are collected in oil, their aggregate is referred to as a reverse micelle. In a reverse micelle, the heads remain in the core while the tails maintain favorable contact with the oil.

the surface of the particles and makes it non-wettable, hydrophobic.

The effectiveness of a particular surfactant additive depends on physical and chemical properties material. A surfactant that has an effect in one chemical system may have no effect or the opposite effect in another. In this case, the surfactant concentration is very important, which determines the degree of saturation of the adsorption layer. Sometimes high-molecular compounds exhibit an action similar to surfactants, although they do not change the surface tension of water, such as polyvinyl alcohol, cellulose derivatives, starch, and even biopolymers (protein compounds). The effect of surfactants can be exerted by electrolytes and substances insoluble in water. Therefore, it is very difficult to define the concept of "surfactant". In a broad sense, this concept refers to any substance that, in small quantities, noticeably changes the surface properties of the dispersed system.

Application of surface active agents

The thermodynamics of surface-active agents is of great importance both theoretically and practically. This is due to the fact that these agents are systems between ordered and disordered states of matter. The surfactant industry owes its dynamic development to the orientation of manufacturing enterprises towards the development and development of innovative products that can be used both in the production of consumer goods and in manufacturing processes.

The classification of surfactants is very diverse and in some cases contradictory. Several attempts have been made to classify according to different criteria. According to Rebinder, all surfactants are divided into four groups according to the mechanism of action:

- wetting agents, defoamers and foaming agents, i.e. active at the liquid-gas interface. They can reduce the surface tension of water from 0.07 to 0.03–0.05 J/m2;

Already started and planned investments allow to gradually expand the offer with innovative products that are developed in accordance with current trends and customer requirements. Surfactants are chemical surfactants with a specific structure that reduce the surface tension of a liquid. This property gives surfactants their versatility and ability to be used in virtually every industry.

Benefits of using surfactants

Due to their function they perform in the respective product recipes or production processes. Surfactants can be divided into the following groups. Surfactants used in the manufacture of cleaning and cosmetic products. Surfactants for industrial applications. . The main groups mentioned above refer to products of various chemical structure, which are divided into the following subgroups.

– dispersants, peptizers;

– stabilizers, adsorption plasticizers and thinners (viscosity reducers);

- detergents that have all the properties of surfactants.

Abroad, the classification of surfactants according to their functional purpose is widely used: thinners, wetting agents, dispersants, deflocculants, foaming agents and defoamers, emulsifiers, and stabilizers of dispersed systems. Binders, plasticizers and lubricants are also released.

According to the chemical structure, surfactants are classified depending on the nature of hydrophilic groups and hydrophobic radicals. Radicals are divided into two groups - ionic and nonionic, the first can be anionic and cationic.

Nonionic surfactants contain non-ionizable end groups with a high affinity for the dispersion medium (water), which usually include oxygen, nitrogen, and sulfur atoms. Anionic surfactants are compounds in which a long hydrocarbon chain of molecules with a low affinity for the dispersion medium is part of the anion formed in an aqueous solution. For example, COOH is a carboxyl group, SO 3 H is a sulfo group, OSO 3 H is an ether group, H 2 SO 4, etc. Anionic surfactants include salts of carboxylic acids, alkyl sulfates, alkyl sulfonates, etc. Cationic substances form in aqueous solutions cations containing a long hydrocarbon radical. For example, 1-, 2-, 3- and 4-substituted ammonium, etc. Examples of such substances can be amine salts, ammonium bases, etc. Sometimes a third group of surfactants is distinguished, which includes amphoteric electrolytes and ampholytic substances, which, depending on by the nature of the dispersed phase, they can exhibit both acidic and basic properties. Ampholytes are insoluble in water, but active in non-aqueous media, such as oleic acid in hydrocarbons.

Japanese researchers propose a classification of surfactants according to their physicochemical properties: molecular weight, molecular structure, chemical activity, etc. Gel-like shells on solid particles arising due to surfactants as a result of different orientations of polar and non-polar groups can cause various effects: liquefaction; stabilization; dispersion; defoaming; binding, plasticizing and lubricating action.

A surfactant has a positive effect only at a certain concentration. There are very different opinions on the issue of the optimal amount of surfactants to be introduced. P. A. Rebinder points out that for particles

1–10 µm required amount Surfactant should be 0.1-0.5%. Other sources give values of 0.05–1% or more for different fineness. For ferrites, it was found that for the formation of a monomolecular layer during dry grinding of surfactants, it is necessary to take at the rate of 0.25 mg per 1 m 2 of the specific surface of the initial product; for wet grinding - 0.15–0.20 mg / m 2. Practice shows that the concentration of surfactants in each case should be selected experimentally.

In the technology of ceramic SEMs, four areas of application of surfactants can be distinguished, which make it possible to intensify physical and chemical changes and transformations in materials and control them during synthesis:

– intensification of the processes of fine grinding of powders to increase the dispersion of the material and reduce the grinding time when the specified dispersion is achieved;

– regulation of the properties of physical and chemical disperse systems (suspensions, slurries, pastes) in technological processes. Here, the processes of liquefaction (or a decrease in viscosity with an increase in fluidity without a decrease in moisture content), stabilization of rheological characteristics, defoaming in dispersed systems, etc. are important;

– control of flame formation processes when spraying suspensions upon obtaining the specified dimensions, shape and dispersion of the spray plume;

– an increase in the plasticity of molding masses, especially those obtained under the influence of elevated temperatures, and the density of manufactured blanks as a result of the introduction of a complex of binders, plasticizers and lubricants.