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Influence of Unsaturations on the Organization and Air Reactivity of Triglyceride Monolayers.

C AzémardM C FauréS StankicS ChenotH IbrahimL LaportePhilippe FontaineM GoldmannLaurence de Viguerie
Published in: Langmuir : the ACS journal of surfaces and colloids (2022)
The behavior of Langmuir monolayers of saturated and unsaturated C18 triglycerides (TAGs) was studied as two-dimensional (2D) models for paint systems at the air-water interface or transferred onto solid films. The organization of saturated tristearin (C18:0) monolayer was probed thanks to grazing incidence X-ray diffraction: one observes a hexagonal packing of the chains perpendicular to the air-water interface, in contrast to what is described in the literature. Conversely, the mono- and polyunsaturated TAGs (triolein C18:1, trilinolein C18:2, and trilinolenin C18:3) monolayers do not present any organization at the air-water interface but do exhibit peculiar reactivity regarding the air atmosphere. The obtained results derived from the evolution of surface pressure-molecular area isotherms and monolayer compressibility under different atmospheres over time, combined with ultrahigh-vacuum infrared (UHV-FTIR) spectroscopy, showed the adsorption of O 2 molecules in the monolayer together with chemical reactions with hydrocarbon chains. The kinetic effect of lead ions, known to be efficient siccative agents in oil paints, was also assessed: the addition of Pb 2+ in the subphase induces an increase of the O 2 adsorption.
Keyphrases
  • aqueous solution
  • high resolution
  • systematic review
  • fatty acid
  • magnetic resonance
  • risk factors
  • magnetic resonance imaging
  • computed tomography
  • risk assessment
  • single molecule
  • quantum dots
  • solid state