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Measurement of surface forces between mica sheets immersed in aqueous quaternary ammonium ion solutions

journal contribution
posted on 1984-07-01, 00:00 authored by P Claesson, Roger Horn, R Pashley
Forces between mica surfaces immersed in Me4NBr, Pr4NBr, and Pe4NBr solutions over a wide concentration range are reported (Me = methyl, Pr = propyl, Pe = pentyl). In each case the cation adsorbs quite strongly onto the negatively charged mica surface and determines the double-layer potential. However, this strong adsorption does not cause complete neutralization of the negative lattice charge apparently because of packing constraints due to the large size of these ions. Adsorption of Me4N+ ions gives rise to a short-range (<2 nm) repulsive force similar to that previously observed between bilayers of CTAB and may be due to the residual hydration of these ions. The large rations also, unexpectedly, give rise to short-range repulsive forces but of a somewhat different nature. In this case, the repulsive forces can be explained by assuming that the large adsorbed ions shift the plane of charge a distance of one ion diameter from the mica surface. At all but very high concentrations these larger ions could be displaced from the mica surfaces on forcing them together. No evidence of any “hydrophobic attraction” was observed between surfaces containing these adsorbed ions. Previous studies on coagulation are discussed in the light of our results.

History

Journal

Journal of colloid and interface science

Volume

100

Issue

1

Pagination

250 - 263

Publisher

Academic Press

Location

Maryland Heights, Mo.

ISSN

0021-9797

eISSN

1095-7103

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1984, Academic Press

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