Please join the Waterloo Institute for Nanotechnology on Thursday May 9, 2019 for a guest lecture by Dr. Hongbo Zeng from the Department of Chemical and Materials Engineering, University of Alberta, Canada. He will be speaking on "Hydrophobic Interactions in Water and Hydrophilic Interaction in Oil of Polymers, Emulsions and Bubbles".
Abstract:
Hydrophobic effects play important roles in a wide range of natural phenomena and engineering processes such as coalescence of oil-in-water emulsions, air flotation of mineral particles, folding of proteins, and assembly of amphiphilic polymers and biomembranes. In this talk, I will review some of our experimental advances in characterizing the hydrophobic interactions of polymer surfaces by direct force measurements at polymer/water and deformable air/water or oil/water interfaces. Results will be shown on the effects of dissolved gas, specific ions, and spontaneous cavitation of confined water film between approaching hydrophobic polymer surfaces in degassed solutions. Synchronous measurements of interaction forces of deformable gas bubbles/emulsion drops with sub-nN resolution and drainage dynamics of confined thin liquid films down to nm thickness were achieved for the first time. We have also quantified the nanomechanics between water-in-oil or oil-in-water emulsion drops and polyelectrolyte surfaces (i.e., zwitterionic, cationic and anionic), and elucidated the intrinsic wetting mechanisms of the polyelectrolyte surfaces. An intriguing long-range “hydrophilic” attraction was found between water drops and polyelectrolyte surfaces in oil, with the strongest interaction measured for the polyzwitterion. These results provide useful insights into the development of novel polymer-based materials and coatings for a wide range of engineering, bioengineering and environmental applications.
Biography:
