The Waterloo Institute for Nanotechnology Seminar Series presents
Hydrophobic Interactions in Water and Hydrophilic Interaction in Oil of Polymers, Emulsions and Bubbles
Dr. Hongbo Zeng
Department of Chemical and Materials Engineering
University of Alberta
Thursday, May 9, 2019
2 - 3 p.m.
All are welcome to attend.
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-inoil 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.
Hongbo Zeng is a Professor in the Department of Chemical and Materials Engineering at the University of Alberta, a Canada Research Chair (Tier 1) in intermolecular forces and interfacial science, and a College Member of The Royal Society of Canada. He received his BSc and MSc degrees at Tsinghua University, and obtained his PhD at the University of California, Santa Barbara under the supervision of Prof. Jacob Israelachvili and Prof. Matthew Tirrell. Dr. Zeng’s research interests are in colloid and interface science, functional materials & nanotechnology, with a special focus on intermolecular and surface interactions in soft matter (e.g., polymers, biopolymers, surfactants and emulsions) and engineering processes. He has published over 230 peer-reviewed research articles in top journals (e.g., Advanced Materials, Angewandte Chemie International Edition, PNAS, ACS Nano, Macromolecules, ACS Applied Materials & Interfaces, Langmuir, Journal of Physical Chemistry B & C), 7 book chapters, and coauthored/edited a book “Polymer Adhesion, Friction and Lubrication” (Wiley). He was a recipient of the Petro-Canada Young Innovator Award (2013), Martha Cook Piper Research Prize (2016), The Canadian Journal of Chemical Engineering Lectureship Award (2016), Engineering Research Award (2018) and Engineering Undergraduate Teaching Award (2018) of the University of Alberta, Hatch Innovation Award of The Chemical Institute of Canada (2018), and Great Supervisor Award (2019) of the University of Alberta.
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