Dynamic Surface Forces

From the moment rain beads on a waxed jacket, a gecko scampers across a wall, or cartilage lets our knees glide, our day is choreographed by surface interaction forces. The “usual suspects” are van der Waals dispersion forces, electrostatic double-layer forces, hydration/structural forces , capillary forces, hydrogen bonding, and polymer-mediated steric or depletion interactions; together they control wetting, adhesion, friction, fouling, and colloidal stability in foods, cosmetics, inks, and biomedical devices.

Engineers and chemists harness them to build functional materials: surfactants and self-assembled monolayers tune surface energy for detergency and anti-fogging; charged or zwitterionic polymer brushes create electrostatic/steric barriers that resist protein adsorption and bacterial adhesion; pH, salt, and solvent quality shift double-layer thickness and ion-specific affinities to steer colloid stability or lubrication; micron-scale textures amplify capillarity to make superhydrophobic or superwetting coatings. A pressing next step is to move beyond “static” control of surface forces and probe how external fields reshape them in real time. We propose a research project that explores electrostimulation and acoustic stimulation on known force–distance laws and binding kinetics.

Situations that will be investigated include: 

1.  Weak electrolytes, where AC electric fields polarize surfaces and induce nonlinear electro-osmotic slip (induced-charge electro-osmosis), reorganizing ion clouds faster than diffusion alone; resulting in time-varying zeta potentials and Debye lengths that can switch double-layer repulsion and drift ligands/receptors together or apart at will;
2. High-frequency out-of-plane vibrations generating squeeze-film pressure and acoustic streaming in nanometric gaps, altering hydrodynamic drainage, confinement, and thus the balance among dispersion, hydration, and electrostatic forces.

By integrating rapid field actuation with force measurements and imaging, the project will map how ion transport and micro-fluid dynamics couple to interfacial energetics, revealing why field-responsive changes in electrostatic and biospecific forces, so ubiquitous in everyday life, remain largely hidden in traditional, equilibrium-centric descriptions.

Public funding alone (i.e. government, region, European, international organization research grant)

Federal funding is confirmed for the whole duration of the PhD (4 years). We also offer the possibility to start an internship (to validate a master’s degree or an engineering diploma for instance) and to pursue with the PhD later.

University of Montreal’s main campus is located at the heart of Montreal city, the most vibrant city for pursuing graduate studies in North America. Recent surveys have placed Montreal as the best place to study in the world and University of Montreal as one of the best universities of the world. Pr Banquy laboratory is located in this unique environment and offers world class research facilities to students willing to pursue their career in materials engineering.

PhD in Biomedical Engineering

Canada

Universite de Montreal

The candidate must be highly motivated by research and material science. Prior experience in an experimental research laboratory is mandatory. Desired qualities are:

• Experience in experimental research in one of the following fields is recommended: materials mechanics, nanotechnology, biomaterials, nanoscale surface characterization, force measurements
• High motivation to carry out a multidisciplinary research project at the interface of engineering, chemistry and biophysics
• Strong appetite for experimentation • Proficiency in spoken and written English
• Team spirit • Scientific curiosity