Dispersion stability due to structural contributions to the particle interaction as probed by thin liquid film dynamics

Journal Article · Tue Dec 01 04:00:00 EST 1992 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00048a023· OSTI ID:5845076

Nikolov, A D; Wasan, D T ^[1]

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1. Illinois Inst. of Technology, Chicago (United States)

Recent experiments on thinning of single liquid films formed from concentrated, monodispersed colloidal dispersions have shown that these films stratify, become thinner, in a stepwise fashion. Stratification has been observed in films formed with surfactant micellar solutions. The phenomenon is explained by us on the basis of the formation of periodic colloid structures induced by structural transition occurring inside the thinning film. We now show that this is a universal phenomenon and present new results for films formed from concentrated suspensions of silica particles as well as polystyrene latexes with a narrow size distribution and prevailing repulsive forces. Using both the reflected light microinterferometric and the transmitted multiple light scattering imaging techniques, the transition from the initial periodic colloid structure to the formation of local particle networks or percolation clusters due to particle bonding or sticking has been observed at high concentrations inside the film for the first time. The effects of particle concentration, size polydispersity, and surfactant concentration on the oscillatory structure stability of films are reported. Calculations are presented for the structural contributions to the disjoining pressure, which arises from particle interactions when the concentration is increased, and this pressure is shown to balance the capillary pressure and to stop the film thinning process. 23 refs., 14 figs.

• OSTI ID: 5845076
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 8:12; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
DISPERSIONS
DYNAMICS
FILMS
MATHEMATICAL MODELS
MECHANICS
MICELLAR SYSTEMS
STABILITY
STRUCTURE FACTORS
SURFACTANTS
THIN FILMS