Levich Institute Seminar Announcement, 09/24/2013
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
City College of CUNY
Chemical Engineering Department
"Nanoparticles at Liquid Interfaces: Rotational Dynamics and Locking"
Interfacial activity of colloidal particles was discovered by Ramsden and Pickering over a century ago. However, the influence of physical and chemical heterogeneity of the particle surface on the interaction with liquid interfaces is the subject of very recent studies. Via Molecular Dynamics simulations, we investigate the impact of surface morphology on the rotational dynamics of nanoparticles straddling a liquid-liquid interface. We find that the effective radius of the nanoparticle and the interfacial free energy can exhibit significant variations as a Brownian particle rotates. Under certain conditions, nanoscale surface features produce energy barriers that are much larger than the thermal energy of the liquid bath. These energy barriers can effectively “lock” the particle at specific angular orientations with respect to the liquid-liquid interface. Hence, surface heterogeneities can entail nontrivial effects such as metastability, slow logarithmic relaxation, and rotational locking. Advances in nanoparticle synthesis allows one to engineer surface heterogeneities that can enable novel industrial applications where the studied effects are highly desirable.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
Ms. Sepideh Razavi is currently a Ph.D. student in Chemical Engineering under the supervision of Professor Ilona Kretzschmar