Woodruff School of Mechanical Engineering
Faculty Candidate Seminar
TOWARDS MANUFACTURING OF HIGH-PERFORMANCE CARBON NANOTUBE ASSEMBLIES
Dr. Mostafa Bedewy
Wednesday, January 29, 2014 at 11:00:00 AM
MRDC Building, Room 4211
Hierarchically ordered carbon nanotubes (CNTs), such as vertically aligned CNT “forests”, are promising for integration in high-performance structural composites, electrical interconnects, thermal interfaces, and filtration membranes. However, manufacturing challenges hinder the realization of commercially viable CNT-based products. These applications typically require CNTs that are monodisperse, well aligned, and densely packed. Moreover, because more than 1 billion CNTs per square centimeter grow simultaneously in a typical chemical vapor deposition (CVD) process, understanding the collective chemical and mechanical effects of growth is key to engineering the properties of CNT materials. In this seminar, I will present tailored synthesis processes, characterization techniques, and mathematical models, which advance the fundamental understanding of self-organized CNT growth and improve manufacturing and metrology of tailored CNT structures. A comprehensive characterization methodology, combining synchrotron X-ray scattering and attenuation with real-time height kinetics, enables mapping the spatiotemporal evolution of CNT diameter distribution, alignment and density. Additionally, in situ transmission electron microscopy (TEM) reveals the S-shaped kinetics of CNT nucleation. Further X-ray data analysis enables modeling the mechanics of entangled CNTs proving that mechanical coupling is not only responsible for the self-organization into the aligned morphology, but is also an important limiting mechanism as significant forces ensue from diameter-dependent CNT growth rates. I will also discuss a mathematical model describing the synergetic chemical coupling among growing CNT micropillars, which predicts height variations, and enables the design of CNT catalyst patterns for improved uniformity. My research reveals how the properties of CNT forests are limited by their spatially evolving morphology, and suggests that mechanochemical interactions limit the collective behavior of CNT assemblies.
Mostafa Bedewy is a Postdoctoral Associate at the Laboratory for Manufacturing and Productivity (LMP) at MIT. He holds a Bachelor’s degree in Mechanical Design and Production Engineering (honors) and a Master’s degree in Mechanical Design, both from Cairo University (received in 2006 and 2009 respectively). In 2013, he completed a PhD at the University of Michigan in Ann Arbor, where he worked on studying the population dynamics and the collective mechanochemical factors governing the growth and self-organization of filamentary nanostructures. Dr. Bedewy then moved to MIT and is now focusing on the scalable manufacturing and applications of nanoparticle clusters and large-area particle crystals by self-assembly. He recently received the Silver Award from the Materials Research Society (MRS) in 2013. His research interests include advanced manufacturing, nanoscale metrology and material characterization, self-assembly of hierarchical nanostructures, and precision engineering.
Refreshments will be served.