New low-cost and eco-friendly surfactants can help cosmetics, petrochemistry, and pharma
1 Apr '21
Russian chemists and their international partners are working on novel surfactants which would serve as eco-friendly replacement for conventional chemicals to be used in the development of skin care products, in crude oil production, and in targeted drug delivery to ailing organs and tissues.
Surfactants are widely used across industries and households, providing the base for synthetic detergents and utilized as additives in construction materials (concrete mixtures, cements, drilling solutions, etc.) and to protect equipment against corrosion.
The so-called gemini surfactants have been proven to be most environment friendly and efficient. They comprise two hydrophilic, or water-attracting, chemical groups. There is a certain aberration among the geminis, though, called counterion-coupled gemini surfactants, aka cocogem surfactants, in which there are both hydrophilic and hydrophobic, or water-repellent, groups of atoms that create bonds between each other.
In partnership with their international colleagues, chemists at Moscow’s RUDN University appear to have synthesized a range of new cocogem surfactants and proven that the novel ones are no second to existing compounds in their performance characteristics. Their method of obtaining such surfactants, which has been published in English, is said to be truly low-cost as the compounds are synthesized at room temperature and no costly reagents are required.
How it worked
To complete the synthesis, the researchers used six different fatty acids. Amines, which were the product of a reaction between hexamethylenediamine and propylene oxide, provided the basis for the novel surfactants’ hydrophilic properties.
Cocogem surfactants synthesis in progress
To actually obtain the surfactants, the chemists dissolved amines and one of the six acids in a 1:2 mol ratio in acetone at room temperature, followed by solvent evaporation. Viscose yellowish liquids that remained were the novel surfactants. Their molecules resulted from electrostatic interaction between oxygen atoms in the acids’ carboxyl groups and amino groups in amines.
The RUDN University team studied carefully the properties of the new compounds, including the key ones such as the ability to reduce surface tension and ensure micelle concentration. These properties are used in cosmetics, for example. The lowest surface tension values achieved in the experiments (around 20mN/m) came with myristic acid based surfactants which thereby showed surface tension reduction performance comparable to that of commercial fluorinated surfactants while beating those in eco-friendliness as the new surfactants are said to be biodegradable.
Foamability and foam stability were two more surfactant parameters that drew the team’s attention. Five out of six novel surfactants formed foam in aqueous solutions; two of these, based on lauric and myristic acids, gave 3-to-4 times the amount of foam the original solution volume could contain. Surfactants based on palmitic and stearic acids had less foam, but the foam they gave showed exceptional stability and lasted up to three days.
These and other parameters the novel compounds have displayed make them a good option for use in cosmetics, medicine, rust protection in construction and industrial projects, and in activity aimed at boosting crude oil yield.
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