Formation and expansion of dark spots in stratifying foam films

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Langmuir; (USA)

DOI:https://doi.org/10.1021/la00096a026· OSTI ID:6219972

Kralchevsky, P A; Nikolov, A D; Wasan, D T; Ivanov, I B ^[1]

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1. Univ. of Sofia (Bulgaria) Illinois Institute of Technology, Chicago (USA)

The stratification of thin liquid films formed from micellar solutions or latex suspensions can be explained by layer-by-layer destruction of a colloid crystal structure inside the film. The stepwise decrease of the film thickness is due to appearance and growth of dark spots (of less thickness) in the film. This phenomenon is analyzed in the present paper, and an explanation is proposed. The driving force for the stepwise thinning of the film is attributed to the gradient of the chemical potential of micelles at the film periphery. Therefore, the appearance and expansion of spots in the film are controlled by the micellar self-diffusion, rather than by normal instabilities. The spots are considered as condensed states of vacancies in the micellar structure inside the film, and the appearance of dark spots is interpreted as a phase transition. This explanation of the mechanism of stratification phenomenon is supported by the data for formation and expansion of spots.

• OSTI ID: 6219972
• Journal Information: Langmuir; (USA), Journal Name: Langmuir; (USA) Vol. 6:6; ISSN LANGD; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
COLLOIDS
DISPERSIONS
ELASTOMERS
FILMS
FOAMS
LATEX
MICELLAR SYSTEMS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PHASE TRANSFORMATIONS
POLYMERS
RUBBERS
STRATIFICATION
SURFACTANTS
THIN FILMS