Seminar: On the Surfactant-Driven Fracture of Particulate Rafts

Over the past decade, much attention has focused on the behavior of hydrophobic particles at interfaces. These systems are of interest to scientists and engineers, for example, due to their potential for stabilizing drops and emulsions via jamming. This seminar will focus on the behavior of particulate rafts, which form when a monolayer of particles are placed at an air-liquid interface. The particles interact with the underlying fluid to form a quasi two-dimensional solid. Such particulate rafts can support both tension and compression, and they buckle under sufficiently large compressive loads. When a drop of surfactant is introduced into the system, fracture networks develop in the rafts. The fracture process exhibits features observed in other elastic systems, such as crack kinking, crack branching, and crack arrest. Moreover, there is a clear coupling between the praft fracture and the diffusion of the surfactant on the surface and through the “porous” liquid-particle monolayer. As such, one can draw analogies between this system and others where crack growth interacts with fluid flow or mass transport.

The seminar will present recent work in modeling the diffusion of surfactant into particle raft systems and the resulting formation of fracture networks. We will present both discrete models that track the motion of individual particles, as well as a new continuum model for poro-chemo-elasticity. Results that reproduce some of the quantitative and qualitative aspects of recent experimental studies of these systems will also be shown.

About the Speaker

John Dolbow is a Professor of Civil and Environmental Engineering at Duke University, where he directs the Duke Computational Mechanics Laboratory.  Professor Dolbow received his BS in Mechanical Engineering from the University of New Hampshire in 1995, and his Ph.D. in Theoretical and Applied Mechanics from Northwestern University in 1999.  He has been a faculty member in the Department of Civil and Environmental Engineering at Duke University since 1999, and his research concerns the development of numerical methods for evolving interface problems.    He has received various awards for his research, including Young Investigator awards from both the USACM and the IACM.   He has held visiting appointments at Harvard University, the Okinawa Institute of Science and Technology, and Sandia National Laboratories.  He is the Editor-In-Chief of the journal Finite Elements in Analysis and Design.  He currently serves as the Vice President for the USACM, as well as on the DOE’s Advanced Scientific Computing Advisory Committee.  

Hosted by Professor Soheil Soghrati.