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Dipl.-Ing. Rolf Isele-Holder

Graduate Student/Structure and Dynamics of Liquid-Liquid and Solid-Liquid interfaces

Diplom in Mechanical Engineering, RWTH Aachen University (2011)

Location: Schinkelstrasse 2, Room 424
Phone: +49 (0)241 80-99136

Wetting and spreading are basic processes in surface sciences that underly many technical applications. An especially fascinating phenomenon in this field is the ultra-rapid spreading of aqueous solutions of trisiloxane surfactants on hydrophobic substrates. Because the spreading velocities are much higher and the final wetted area of the spreading droplet is much larger than what is observed with other surfactant solutions, this phenomenon is known as superspreading. The ability to facilitate this process is why trisiloxane surfactants, which are also called superspreaders, are used in many products such as paints, cosmetics, and herbicides. Despite numerous experimental studies, the driving mechanisms of this process, and especially the role of the trisiloxane surfactant, are still under debate. One of the motivating factors for this is that experiments still cannot resolve the relevant actions at the molecular scale.

My aim in this project is to shed light on the role of the trisiloxane surfactant in the superspreading process. I perform molecular dynamics simulations of the trisiloxane surfactants at various interfaces and in various settings. This work includes the development of efficient algorithms and molecular models needed to perform meaningful simulations. In the long run, we hope that results of our simulations will contribute to the understanding of superspreading and in this way facilitate the development of alternative, environmentally friendlier superspreading agents.
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Top: Trisiloxane surfactants at a water interface. Bottom: Same image without water molecules.

  • R.E. Isele-Holder, W. Mitchell, J.R. Hammond, A. Kohlmeyer, and A.E. Ismail. Reconsidering dspersion potentials: Reduced cutoffs in mesh-based Ewald solvers can be faster than truncation. J. Chem. Theory Comput., 9, 5412-5420 (2013).
  • R.E. Isele-Holder, W. Mitchell, and A.E. Ismail. Development and application of a particle-particle particle-mesh Ewald method for dispersion interactions. J. Chem. Phys., 137, 174170 (2012).
  • R.E. Isele-Holder, B.D. Rabideau, and A.E. Ismail. Definition and Computation of Intermolecular Contact in Liquids using Additively Weighted Voronoi Tessellation. J. Phys. Chem. A, 116, 4657-4666 (2012).