Application of Amphoteric Surfactant in Surface Modification of Powder

Surfactant refers to a substance that can significantly change the interface state of the solution system by adding a small amount. It is commonly called "industrial monosodium glutamate" in the industry and belongs to the fine chemical industry. It is located at the end of the chemical industry chain, and the upstream is derived from petroleum. And natural oil derivatives as raw materials, the downstream can cover almost all fine chemical fields. In terms of physical and chemical properties, it has fixed hydrophilic and lipophilic groups, which can be aligned on the surface of the solution.

In practical applications, surfactants are flexible and diverse due to a series of physical and chemical functions such as wetting or anti-sticking, emulsification or demulsification, foaming or defoaming, solubilization, dispersion, washing, anti-corrosion, and antistatic. , Fine chemical products with a wide range of uses. In addition to being used as detergents in daily life, other applications of surfactants can cover almost all fine chemical fields.

1 Surfactant classification

Surfactants are divided into ionic surfactants (including cationic surfactants and anionic surfactants), nonionic surfactants, amphoteric surfactants, compound surfactants, other surfactants, etc.

1.1According to the source:

Synthetic surfactants-hydrocarbons mainly derived from petrochemicals.

Natural surfactants-biosurfactants using natural oils as raw materials-are composed of bacteria, yeast and real

Bacteria and other microorganisms.

1.2 According to different hydrophilic groups:

①Fatty acid series-can be obtained by microbial culture, covering mycolic acid, penicillin spore acid sodium salt and alkyl amine salt, super washing ability.

② Phospholipids-made from soybeans and egg yolks, and are the main raw materials for preparing liposomes.

③Glycolipid series-it is obtained by Pseudomonas in the culture medium with n-alkane as the sole carbon source, and is used in food medicine and biological preparations.

④Acyl peptide series-cultured with Bacillus subtilis, with good surface activity, such as lipopeptide of active protein.

⑤Bio-polymer surfactants-use the catalytic activity of enzymes to make gelatin and other water-soluble proteins react with the alkyl groups of amino acids.

1.3 According to the hydrophilic nature of the surfactant

Divided into anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants and so on.

①Anionic surfactant

Part of the negatively charged surface active agent that plays a surface active role after ionization in water is called an anionic surface active agent. Structurally, anionic surfactants are divided into four categories: carboxylate, sulfonate, sulfate and phosphate.

②Amphoteric surfactant

Anions and cations can be formed on the same molecule in an aqueous solution to form internal salts. Mixed with other surfactants, it has good compatibility and synergy, and has strong functionality.

③Non-ionic surfactant

It can be dissolved in water and organic solvents, can be strongly adsorbed on solid surfaces, and has high hard water resistance; it is easy to form micelles in the synthesis of nanomaterials, and it is widely used in nanopowders. 

2 The role of surfactants in material preparation

2.1 Control particle size and shape

The molecular structure of the surfactant determines that it will inevitably form micelles in solution, and the size and number of micelles can be determined by controlling the structure of the surfactant.

2.2 Improve particle surface performance

Surfactants can control the hydrophilicity or lipophilicity and surface activity of the particles, and modify the surface of the nanoparticles; the hydrophilic groups combine with the surface groups to form a new structure; reduce the surface energy to make them in a stable state and form The steric hindrance prevents reunion.

2.3 Control material structure

The amphiphilic structure of the surfactant determines that it can form a molecular directional arrangement on the surface of the solution. Using this characteristic, a surfactant with a specific structure can be used to prepare an ideal structural material.

For example, polymerizable monomers using polymer surfactants form an oriented arrangement in solution. Then the polymerization is initiated, and the nanostructured material with the same structure as the original micelle can be obtained.

3 Application of surfactants

3.1 Application in nanotechnology research

In the field of nanomaterial preparation, various nanomaterials have been successfully prepared by using the ordered aggregates formed by surfactant molecules in the dispersion system, such as micelles, reverse micelles, and microemulsions. Cationic surfactants, as intercalation modifiers of inorganic silicates, can play an important role in the preparation of polymer-based-inorganic nanocomposites. When solving the problem of agglomeration of nano powders, modification with surfactants can reduce the huge surface energy of nano powders, which is an important means to inhibit the agglomeration of nano powders. From the preparation, characterization and application of nanomaterials, surfactants play an important role due to their unique properties.

3.2 Application in the pharmaceutical industry

Surfactants are used as pharmaceutical excipients in pharmaceutical preparations, as phase transfer catalysts in drug synthesis, and as solubilizing sensitizers in drug fluorescence analysis, so they are widely used in the pharmaceutical industry.

3.3 Application in environmental protection research

Surfactants occupies an important position in the research of water pollution treatment technology, atmospheric dust removal technology, soil and groundwater pollution remediation technology. For example, the research of surfactant solubilization remediation technology is a major research topic to solve soil and groundwater pollution remediation, and it has achieved good results in theoretical and laboratory research.

In addition, surfactants are also widely used in petroleum/coal mining and electroplating and leather fields.

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