Aqueous foams stabilized by laponite and CTAB

Aqueous foams prepared by cetyltrimethylammonium bromide (CTAB) and disk-like Laponite particles dispersions are studied. The particle/CTAB dispersions have a synergistic effect on foam stability at intermediate CTAB concentrations. The foam stability increases with increasing particle concentration. At a fixed particle concentration, the foam stability first increases with increasing CTAB concentration and reaches a maximum at a CTAB concentration around 1.7 cec. After that, the foam stability decreases and then remains unchanged. The effects of hydrophobicity and electrical property of modified Laponite particles on foam stability are discussed. The hydrophobicity of Laponite particles is predominant in stability of foams compared with the electrical property of particles. The most stable foams were obtained by particles with the maximum hydrophobicity (the contact angle is still smaller than 90 degrees). Two mechanisms promote foam stability: (a) adsorption of modified particles on the bubble surface; (b) formation of an aggregate structure by the armored bubbles and particles in the bulk phase, which is confirmed by laser-induced fluorescent confocal microscopy. (C) 2007 Elsevier B.V. All rights reserved.