|Structural and thermodynamic signatures of marine microlayer surfactant films|In: Journal of Sea Research. Elsevier/Netherlands Institute for Sea Research: Amsterdam; Den Burg. ISSN 1385-1101, more
|Also published as |
- Pogorzelski, S.J.; Kogut, A.D. (2003). Structural and thermodynamic signatures of marine microlayer surfactant films, in: Ohlson, M. et al. (Ed.) Proceedings of the 22nd Conference of the Baltic Oceanographers (CBO), Stockholm, Sweden, 25-29 November 2001. Journal of Sea Research, 49(4): pp. 347-356, more
Enthalpy; Entropy; Structural dynamics; Surface films; Surfactants; Thermodynamic properties; ANE, Baltic, Gdansk Gulf [Marine Regions]; Marine
|Authors|| || Top |
- Pogorzelski, S.J.
- Kogut, A.D.
Natural surface film experiments in inland waters and shallow offshore regions of the Baltic and Mediterranean Seas were carried out in the time period 1990-1999 under calm sea conditions using a novel device for sampling and force-area studies. The sampler-Langmuir trough-Wilhelmy filter paper plate system `cuts out' an undisturbed film-covered sea area to perform pi-A studies without any initial physico-chemical sample processing. The limiting specific area Alim (2.68-31.57 nm2/molecule) and mean molecular mass Mw (0.65-9.7 kDa) of microlayer surfactants were determined from the 2D virial equation of state applied to the isotherms. Enthalpy deltaH and entropy deltaSt of the 2D first-order phase transitions were evaluated using the Clausius-Clapeyron equation applied to the isotherms. Miscibility of film components and film structure evolution is expressed by the scaling exponent y adopting the 2D polymer film scaling theory. The stress-relaxation measurements revealed a two-step relaxation process at the interface with characteristic times T1=1.1-2.8 and T2=5.6-25.6 seconds suggesting the presence of diffusion-controlled and structural organisation relaxation phenomena. The obtained results suggest that natural films are a complex mixture of biomolecules covering a wide range of solubilities, surface activity and molecular masses with an apparent structural organisation exhibiting a spatial and temporal variability.