The effects of temperature and surface roughness on mass and viscoelasticity of an adsorbed surfactant layer were monitored using the quartz crystal microbalance with dissipation (QCM-D). Adsorption isotherms at 20, 30, 40, 50 and 60�C and at two different roughnesses on gold were measured using cetyltrimethylammonium bromide (CTAB). All isotherms displayed an increase in mass and dissipation as surfactant concentration was increased to its CMC and, for isotherms above the Krafft temperature of CTAB, roughly 25�C, adsorption reached a peak followed by a slight decrease to a plateau at the equilibrium adsorption value. As the temperature was increased the same trend observed with increasing concentration was seen, but adsorbed mass was decreased at equilibrium. Adsorbed mass was decreased further by increasing substrate roughness, where a decrease in the peak height above the equilibrium value was also observed, while the dissipation was increased. Previously, our group reported a large peak at the CMC for rough surfaces at room temperature which was attributed to impurities; in this work the peak is much smaller which we attributed to the fact that helium sparging and ultrasonic degassing of the surfactant solution was performed prior to contact with the substrate surface in this series of experiments.

Observing the effects of temperature and surface roughness on cetyltrimethylammonium bromide (CTAB) adsorption using quartz-crystal microbalance with dissapation

247th National Meeting (2014)

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