Cationic surfactants are positively charged soaps or detergents that can emulsify oily dirt and are good bactericides. They are attracted to negatively charged sites and are used as fabric softeners.
Cationic surfactants are basically soaps or detergents, where the hydrophilic, or water-loving, end contains a positively charged ion, or cation. Typical examples are the chlorides of trimethylalkylammonium and the chlorides or bromides of benzalkonium and alkylpyridinium ions. They are all examples of quats, so named because they all contain a quaternary ammonium ion.
All soaps, or surfactants, short for surfactant agents, work on the same basic principle, based on the fact that most substances in nature are hydrophilic, or water-loving, or lipophilic, or fat-loving. Hydrophilic substances dissolve easily in water, and lipophilic substances dissolve in hydrocarbons, which are organic compounds containing a lot of carbon and hydrogen.
The usual task of these soaps or detergents is to make lipophilic substances, such as oils, fats and greases, water-soluble so that they can be washed away. Since water readily dissolves ionic substances, or materials that contain one or more charged atoms, and hydrocarbons dissolve oils, fats, and greases, a detergent molecule has a hydrocarbon end and an ionic end. The hydrocarbon end of the soap molecule dissolves in a fat or oil particle, leaving the ionic end exposed to the water.
When enough soap molecules have incorporated their hydrocarbon ends into the particle, the surrounding water molecules attract the ionic ends of the surfactant. The particle is then emulsified or suspended in water. In this form, it can be rinsed.
The hydrophilic portion of a surfactant can be of four types. It can be non-ionic but still very soluble in water; zwitterionic, meaning that it contains both positive and negative charges; anionic, or negatively charged; or cationic, which is positively charged. The charge on the ionic moiety significantly influences the surfactant properties.
Soaps, strictly defined, are always anionic, so the charged end has a negative charge. They are very effective at emulsifying oily dirt and keeping it suspended in water, and have good foaming properties. They can, however, react with metal ions found in hard water, such as calcium and magnesium, to form insoluble soap scum.
Cationic surfactants are almost all man-made and their ionic part is positively charged. They are also good emulsifying agents and do not form insoluble foams with positively charged hard water ions. These surfactants have also been found to be good bactericides and some find use as topical antiseptics. Their germicidal properties make them particularly useful in bathrooms and hand sanitizers.
Additionally, cationic surfactants are attracted to the negatively charged sites found naturally on most tissues. They can bond to these sites and provide the fabric with a soft, luxurious feel. For this reason they are often used as fabric softeners.
Protect your devices with Threat Protection by NordVPN
