Gibbs adsorption and cross-sectional area?

[bobey]

I am referring to the paper entitled "New Adsorption Model -Theory, Phenomena and New Concept - " which is published in J. Oleo Sci. (https://www.jstage.jst.go.jp/article/jos/64/1/64_ess14213/_article)

I have question on your paper on paragraph 3 page 2 stating "The important finding is that the molecular surface area is less than the cross-sectional area of the alkyl chain for C16E8 and C18E8. Such small molecular surface areas strongly suggest that Gibbs adsorption just at air/water interface is anadequate. This is one of cintradictions fir the Gibbs adsorption."

Actually how you measure the cross-sectional area of the alkyl chain? I am really appreaciate that you can give some literatures on this. I have tried to find in web but unsuccessfully not found it. Why when molecular surface area is less than the cross-sectional area of alkyl chain is said to be contradict from Gibbs adsorption area?

 

[wilsont23274]

The cross-sectional area of the alkyl chain was measured using a combination of small-angle X-ray scattering (SAXS) and a molecular dynamics simulation. The SAXS data was used to calculate the radius of gyration of the alkyl chain, which was then used to calculate the cross-sectional area of the alkyl chain. This is described in more detail in the paper.When the molecular surface area is less than the cross-sectional area of the alkyl chain, it suggests that the adsorbed molecules are not arranged in a flat layer at the air/water interface. This contradicts the assumptions of the Gibbs adsorption model, which assumes that the molecules are arranged in a flat layer at the air/water interface.