Monolayers or Langmuir Films

Surface-pressure/surface-area isotherms provide valuable insight into the molecular packing of surfactants in monolayers. A steep slope in the n-A curve 

Investigation of thermodynamic behavior of monolayers formed from mixtures of bis[2-(n-hexadecanoyl)ethyl]methyl(4-vinylbenzyl) ammonium chloride (1) and dioctadecyl-dimethylammonium bromide (5) serves as the second example [116]. The determined surface-pressure/surface-area isotherms of mono-layers prepared from (1) and (5) and from their mixtures are given in Fig. 8. The isotherms showed the expected behavior following the liquid state there was a transition to the solid state in the region of 20-36 mNm 1. This transition was characterized by a pressure, and by a corresponding area, Aj. All isotherms intersected in the vicinity of 30 mNm-1 and, at surface-pressure/surface-area 

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