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Change of Surface Structure upon Foam Film Formation
Author(s) -
Ridings Christiaan,
Andersson Gunther G.
Publication year - 2015
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402821
Subject(s) - pulmonary surfactant , materials science , surface charge , charge density , chemical physics , molecule , thin film , electric charge , electrochemistry , scattering , surface pressure , molecular dynamics , chemical engineering , analytical chemistry (journal) , composite material , chemistry , nanotechnology , electrode , optics , chromatography , organic chemistry , computational chemistry , physics , quantum mechanics , engineering , mechanics
The charge distribution and coverage with surfactant molecules at foam film surfaces plays an important role in determining foam film structure and stability. This work uses the concentration depth profiling technique neutral impact collision ion scattering spectroscopy to experimentally observe the charge distribution in a foam film for the first time. The charge distribution at the surface of a foam film and the surface of the corresponding bulk liquid were measured for a cationic surfactant solution and the surface excess as well as the electric potential were determined. Describing the internal pressure of foam films by using the electrochemical potential is introduced as a new concept. The foam film can be seen to have a more negative surface charge compared to the bulk liquid surface due to re‐arranging of the surfactant molecules. It is discussed how the change in surface excess and electric potential change the electrochemical potential and the stability of the foam film.