micelle
(rus. мицелла)
—
a particle of superfine colloid with liquid dispersion medium comprising a core and stabilizing surface layer. Average size of micelles ranges from 1 nm to 100 nm.
Description
Micelles are particles contained in lyophilic colloids (solutions of surfactants). In lyophilic sols, a micelle is an association of molecules (aggregates consisting of dozens and hundreds of amphilic molecules). A hydrophobic radical in each molecule is fixed to a polar (hydrophilic) group. When a micelle develops, several dozens or hundreds of molecules aggregate in such a manner that hydrophobic radicals form a core (inner element), while hydrophilic groups form the surface layer of a micelle. The concentration of surfactants in a solution that promotes development in the system of stable micelles balanced with non-associated molecules of surfactant is known as critical micelle concentration. If the dispersion medium is represented by an organic liquid, molecules in a micelle may have a reverse orientation, when the core is made up of polar groups, and hydrophobic radicals are turned inwards (reverse micelle).
In lyophilic hydrosols stabilised with electrolyte fluids, the core of a micelle is enclosed in two layers of opposite charged ions, i.e. in an electrical double layer. The diffuse ion layer prevents the convergence and aggregation (bonding) of particles.
In lyophilic hydrosols stabilised with electrolyte fluids, the core of a micelle is enclosed in two layers of opposite charged ions, i.e. in an electrical double layer. The diffuse ion layer prevents the convergence and aggregation (bonding) of particles.
Illustrations
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Spherical micelle structure layout.
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Authors
- Govorun Elena N.
- Gusev Alexander I.
- Khokhlov Alexey R.
Sources
- Suzdalev I.P. Nanotechnology: Physics and Chemistry of Nanoclusters, Nanostructures and Nanomaterials (in Russian). — M.: KomKniga, 2006. — 592 pp.
- Evans D., Wennerstrom H. The Colloidal Domain: Where Physics, Chemistry, Biology, and Technology Meet. 2nd ed. — N.Y.: Wiley, 1994. — 672 p.
- IUPAC. Compendium of Chemical Terminology. 2nd ed. // Gold Book. — 1997. Compiled by A.D. McNaught, A. Wilkinson. — Oxford: Blackwell Scientific Publications, 1997. XML on-line corrected version: http://www.goldbook.iupac.org, 2006. Created by M. Nic, J. Jirat, B. Kosata. Updates compiled by A. Jenkins. Last update 07.09.2009.