- Understanding and control of Marangoni effect in forced wetting by surfactant and protein solutions
Understanding and control of Marangoni effect in forced wetting by surfactant and protein solutions
Understand and control the change of the advancing and receding contact angle of surfactant and protein solutions depending on the wetting speed.
Originality and innovative aspects: We recently showed that surfactants can drastically change the dynamic contact angles, even at concentrations below the Critical Micelle Concentration (CMC), which can be attributed to the Marangoni effect. This has drastic consequences for printing and coating processes, because liquids used in such processes typically contain surfactants. In order to examine the dynamic wetting at time scales relevant to practical applications, the time resolution of at least 1 ms will be reached. The experiments will be extended to dispersions and emulsions.
Methodologies: The existing experimental setups will be modified for further investigations and manipulation of the dynamic contact angle. Currently the advancing and receding contact angles are measured by a video camera on a rotating cylinder. In this WP we shall use the pattern of a laser beam reflected from the region around the three-phase contact line to obtain contact angle values with high precision and with a time resolution of better than 1 ms. With a modified Wilhelmy plate setup a large surface area will be examined.
 D. Fell, G. Auernhammer, E. Bonaccurso, C. Liu, R. Sokuler, H.-J. Butt, Langmuir 27, 2112-2117 (2011); D. Fell, N. Pawanrat, E. Bonaccurso, H.‑J. Butt & G.K. Auernhammer, Colloid & Polymer Sci. 2012, DOI 10.1007/s00396-012-2759-y.
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