11/14/2023
By Fanglin Che
Title: Interfacial colloidal interactions, dynamics, and assembly: from biomembranes to ordered 2D materials
Prof. Peter Beltramo
Department of Chemical Engineering, University of Massachusetts, Amherst, MA, USA
Abstract:
Soft matter interfaces are ubiquitous across diverse technologies ranging from pharmaceuticals to chemical formulations. The presence of surfactant molecules or colloidal particles at fluid interfaces gives the interface distinct properties in response to flow, deformation, and external fields that must be measured, understood, and manipulated for desired functionalities. This talk will focus on colloidal interactions in two such systems: crowded artificial biological membranes and anisotropic particles at air-water interfaces. In the first part of the talk, we discuss the effects of increasing concentration of model membrane inclusions in an artificial cell membrane on inclusion diffusivity and the apparent viscosity of the membrane. In the second part of the talk, we highlight our recent discovery that particle surface porosity severely attenuates the capillary attraction between colloidal ellipsoids at fluid interfaces, enabling the development of ordered anisotropic 2D monolayers. By monitoring the dynamics of two particles approaching one another, we find that porous particles exhibit a strikingly shorter-range capillary interaction potential. Interferometry measurements of the fluid deformation surrounding a single particle quantitatively confirm the decrease in capillary interaction energy and point to roughness-induced changes to interfacial pinning as the mechanism for reduced attraction. Lastly, we show how this reduction in interparticle capillary attraction and alteration in interfacial pinning manifests in the overall 2D interfacial assembly of such particles, informing an approach for the development of anisotropically ordered 2D materials.
Biography:
Peter Beltramo is an Assistant Professor in the Department of Chemical Engineering at UMass Amherst. He earned a BS in Chemical Engineering from the University of Pennsylvania in 2009 and a Ph.D. in Chemical Engineering from the University of Delaware in 2014, where he studied the electrokinetics and self-assembly of colloidal suspensions. Before starting at UMass Amherst in 2018, he completed a postdoc in Soft Materials at ETH Zurich. At UMass, his lab studies interfacial soft matter in contexts ranging from membrane biophysics and biomimetic materials to particle stabilized emulsions and ordered 2D materials. His recent recognitions include the NSF CAREER Award, ACS-PRF Doctoral New Investigator Award, and a Lilly Teaching Fellowship at UMass Amherst.