Monomolecular surface films

When the filming amine condenses, the hydrophilic polar radical of the molecule (the head) adsorbs onto the metal surface and the hydrophobic, long chain (the tail) is directed at a 90° angle of inclination away from the metal surface. Provided the feed rate is adequate, the critical concentration is eventually reached and a continuous monomolecular surface film is formed. At this stage, the physical size of the interstices between the polar groups is smaller than the molecules of water, carbon dioxide, or oxygen, and these molecules are thus physically prevented from reaching the metal surface. 

W.D. Garrett, Reply to comment on retardation of water drop evaporation with monomolecular surface films, J. Atmos. Sci. 29 (1972) 786-787. 

The term lamina will sometimes be used in order to avoid confusion with the monomolecular surface films which are so important for the stability of isolated liquid films. 3 Works, 1, 300 ff. 

Typically, these films are deposited using the following procedure. A flat, shallow container, such as a Langmuir-Adam surface balance, is filled with water (or other suitable liquid) and the substrate to be coated is immersed. Then a solution of the amphiphilic material, in a solvent that is insoluble in water, is deposited dropwise onto the water, thereby forming an oriented monomolecular surface film upon evaporation of the solvent. This film can then be compacted... 

Alpers, W. Huhnerfiiss, H. (1983). Molecular aspects of the system water/monomolecular surface film and the occurrence of a new anomalous dispersion regime at 1.43 GHz. J. Phys. Chem. 87, 5251-5258. 

Hiihnerfuss, H, Walter, W, (1983). The thermal anomaly of relaxation effects in monomolecular surface films. J. Colloid Interface Sci. 97,476—480. 

Fig. 1. Schematic sketch of a monomolecular surface film being formed by surface-active compounds that consist of a hydrophobic and a hydrophilic part...

Monomolecular surface films change the structure of the uppermost water layer within a thickness of around some micrometers to possibly some hundred micrometers (Huhnerfuss and Alpers 1983, Huhnerfuss 1986). For example, ice-like clathrate structures are induced by OLA films in a water layer of d < 190 pm. Furthermore, the surface potential of pure water of about - 180 mV becomes positive and may approach values of > 400 mV (Gericke and Huhnerfuss 1989), and the dilational surface viscosity is drastically increased (Huhnerfuss 1985). The relaxation time for disturbances of the surface film order TCOmp attains values of around 10 to 20 min, which are about 1013 times larger than the relaxation time xs of the water molecules (Huhnerfuss and Alpers 1983). 

Huhnerfuss H, Lange P, Walter W (1984) Wave damping by monomolecular surface films and their chemical stmcture. Part II Variation of the hydrophylic part of the film molecules including natural substances. J Mar Res 42 737-759... 

The results from the wind-wave tank measurements show that at X- and Ka-band the radar backscattering from a slick-free water surface is caused by bound as well as by free propagating ripples. In the presence of a monomolecular surface film at certain wind speeds only bound or only free propagating ripples are responsible for the backscattering at X-band, which can explain higher measured damping ratios. 

Huhnerfuss H (1986) The molecular structure of the system water/monomolecular surface film and its influence on water wave damping. Habilitationsschrift, Univ. Hamburg, Dept, of Chemistry, Hamburg, Germany, 245 pp... 

Since the 1960s natural surface films ( sea slicks ), that tend to exhibit thicknesses of one molecule only, have been in the focus of interdisciplinary research that required input by various disciplines such as oceanography, meteorology, physics and chemistry. Albeit the thickness of such monomolecular surface films is small compared to that of mineral oil films their wave damping capability and, thus, their influence on air-sea interactions is comparable. Consequently, they are still often mixed up with mineral oil films ( oil spills ), particularly in the Same of remote sensing applications. It is the aim of the present book to provide a scientific basis that allows avoiding such misinterpretation in the future. 

Garrett, W. D., and W. R. Barger. 1970. Factors Affecting the Use of Monomolecular Surface Films to Control Oil Pollution on Water, Environmental Science and Technology, voL 4, pp. 123-127. 

Nakamura H, Tonosaki A, Washioka H, Takahashi K, Yasui S. Monomolecular surface film and tubular myelin figures of the pulmonary surfactant in hamster lung. 

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