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(physical chemistry)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a layer of a substance 1 molecule thick on a surface or at a phase boundary. Monolayers are produced by adsorption, surface diffusion, and evaporation of a solvent from a solution containing a nonvolatile component. Monolayers that are formed by surface-active substances on the surface of a liquid or at the boundary between two nonmiscible liquids may exist in various two-dimensional states (gaseous, condensed, and intermediate, or “liquid-expanded”).

In gaseous monolayers, the distance between the molecules is great relative to their size; therefore, cohesive molecular interactions are virtually absent. On the other hand, condensed monolayers have limiting molecular packing density. In the case of fatty acids, alcohols, and other molecules that may be represented as hydrocarbon chains with a polar terminal group, condensed monolayers resemble “picket fences” occupying the entire surface area. Each molecule in such a “fence” is arranged perpendicularly or at an angle to the phase boundary surface and, regardless of its own length, usually occupies an area of 20–25 square angstroms. As a rule, linear macromolecular compounds form monolayers with horizontal orientation of the macromolecules. If the cohesion is sufficiently high, monolayers may have surface viscosity and strength that differ sharply from those of the bulk phases.

The structure and properties of monolayers have a strong effect on mass transfer (evaporation and diffusion), catalysis, friction, adhesion, and corrosion; this is taken into account in solving various engineering and industrial problems. The stability of highly disperse systems (sols, emulsions, and suspensions) often depends predominantly on the state of a monolayer.

Monolayers also play an important role in biological systems. For example, there are membrane structures in all cells of living organisms. Biological membranes basically consist of two monolayers of protein molecules with a double (bimolecular) layer of lipids between them. The thickness of such a four-layer membrane is 70–80 angstroms. The alternation of various types of monolayers also results in the lamellar structure of certain cell organelles, such as chloroplasts in the cells of green plants. Artificial monolayers are used as models of biological membranes in studying their structure and function.


Adamson, A. W. Physical Chemistry of Surfaces, 2nd ed. New York, 1971.
Gaines, G. L. Insoluble Monolayers at Liquid-Gas Interfaces. New York [1966].
Beredjick, N. “Issledovanie monomolekuliarnykh sloev polimerov.” In Noveishie melody issledovaniia polimerov. Moscow, 1966. Chapter 16. (Translated from English.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Independently of the presence or absence of obvious hydrophobic parts like a long hydrocarbon chain, the aromatic rings arranged in the same plane could be stacked by [pi]-[pi] interactions by the method of organized molecular films. Layer spacing in the multilayers of the aromatic polyamides was not dependent on the length of the hard and soft segments and always indicated a constant value.
Liu, "Phase behaviors and 2D-3D morphological transition of aromatic Schiff base derivatives in organized molecular films," Acta Physico-Chimica Sinica, vol.
Characteristics of morphological formation of organized molecular films of PLLA are a bundle like texture (Fig.
As mentioned previously, it is possible to control the surface morphologies of the mixed monolayers for organic polymer and inorganic materials by organo-modification of clay surface and the method of organized molecular films. It is possible to apply this type patterned thin film material made by bio-degradable organic polymers and mining natural clays as next generation ecomaterial, for example, bio-chips implanted to human body.
"The technique provides a particularly versatile method that will allow fabrication of ordered molecular films drawn from a wider range of materials," writes Friend in an editorial accompanying the research report in the Aug.
This result will be very important information on the size and on the control of the dispersion degree for each domain related to surface pattering, on the occasion of formation for the organized molecular films, as in the following discussion.
Molecular Arrangement of Organized Molecular Films for Fluorinated Comb Copolymers
These profiles indicate the packing mode in the organized molecular films of these copolymer system analogous to the bulk state.
Molecular Films which arc more occlusive, minimizing transpi-dermal water loss (TEWL) and enhancing the release of the active ingredients into the skin.

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