Two‐dimensional surface properties of 2‐methoxy ethyl oleate at the air/water interface

• Published in: Journal of the American Oil Chemists' Society Vol. 76; no. 7; pp. 853 - 858
• Main Authors: Baskar, Geetha, Venkatesan, S., Dhathathreyan, Aruna, Mandal, A. B.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-07-1999; Springer; Springer Nature B.V
• Subjects: Biological and medical sciences; Chemistry; Collapse pressure; Compressibility; compressibility coefficient; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gas-liquid interface and liquid-liquid interface; General and physical chemistry; isotherm; Isotherms; Langmuir film balance; methoxy ethyl oleate; Molecular biophysics; Molecular structure; Oleic acid; Pressure; relaxation rate; Surface area; Surface physical chemistry; Surface properties; Surface properties. Adsorption; Amphipathic compound; Biochemical analysis; Non ionic surfactant; Two dimensional structure; Lipids; Langmuir method; Air water interface; Surfactant; Polar compound; Experimental study; Modeling; Biofilm; Surface properties; Comparative study; Lipid ester; Physicochemical properties
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-999-0076-5

Methoxy ethyl oleate, a nonionic surfactant, has been investigated at the air/water interface for various surface properties by employing the Langmuir film balance technique. The ester forms an expanded isotherm at the air/water interface. The minimum area of packing (A0), initial area of increase of surface pressure (Ai), collapse pressure (πc), and area/molecule at collapse pressure (Ac) have been estimated from the isotherm curve. The higher compressibility coefficient (K) suggests that the ester forms a more expanded liquid film than the parent oleic acid. Besides, the ester film is fairly stable as suggested by only about 30% loss in area over a period of 20 min. The relaxation rates of the ester film at different surface pressures of 10, 15, and 20 mN·m−1 have been estimated from changes in the surface area/molecule with time. Interestingly, the surface area (54.2 Å2/molecule) that corresponds to a minimized structure projected for the ester, calculated theoretically, agrees reasonably well with the experimental value (57.2 Å2/molecule).