[CCoE Notice] Seminar: Visualization of Surface-Active Bottlebrush Additives through Time-of-Flight Secondary Ion Mass Spectroscopy * CBB 108 * 10:30 am, Friday, April 19, 2019 * Rafael Verduzco * Rice University *

[Knudsen, Rachel W]

***** Seminar *****
Department of Electrical and Computer Engineering
Materials Engineering Program
Center for Integrated Bio and Nano Systems
  April 19, 2019
10:30 a.m., Room: CBB 108
Visualization of Surface-Active Bottlebrush Additives through Time-of-Flight Secondary Ion Mass Spectroscopy
Rafael Verduzco
Chemical and Biomolecular Engineering and Materials Sciences and NanoEngineering
 Rice University
Abstract: The composition of polymer blends near interfaces can differ from the average blend composition, even when the distinct constituents are miscible. Understanding the processes that control the composition at a surface is important for many practical applications, including the preparation of antifouling surfaces, alignment of block copolymer films, and tailoring the properties of organic electronic devices. Here, we study surface segregation of highly branched bottlebrush polymer additives, which leverage an entropic effect to drive high surface energy polymers to interfaces, and we apply time-of-flight secondary ion mass spectroscopy (ToF-SIMS) to study the phase behavior of blends of bottlebrush polymers with linear polymers. ToF-SIMS enables three-dimensional compositional analysis using a focused ion beam along with an argon cluster beam for depth profiling. Combined with atomic force microscopy (AFM), topographical and compositional information can be acquired simultaneously. We quantify the composition of bottlebrush throughout the film by calibration of ion intensity ratios, and self-consistent field theory calculations elucidate the enthalpic and entropic contributions to segregation. We show that surface segregation can be controlled and predicted by the number of branches in the bottlebrush polymer, and the chemistry and molecular weight of the linear polymer. This study demonstrates that bottlebrush copolymer additives provide a route to decouple the surface functions of a film from the bulk chemistry and highlights the capabilities of ToF-SIMS for 3-D imaging of multicomponent materials.
Bio: Rafael Verduzco is an Associate Professor in Chemical and Biomolecular Engineering and Materials Sciences and NanoEngineering at Rice University. Verduzco received his Ph. D. in Chemical Engineering from the California Institute of Technology in 2007 and his BS in Chemical Engineering from Rice University in 2001. The Verduzco laboratory uses a combination of materials synthesis and multi-scale characterization tools to develop new materials for organic photovoltaics, energy storage, antifouling coatings, water purification, and shape-programmable systems. Verduzco received an NSF CAREER award in 2015 for the study and development of all-conjugated block copolymers. He has led successful interdisciplinary projects supported by the National Science Foundation, the Welch Foundation, and the Department of Energy, and he organized the 2017 International Liquid Crystal Elastomers Conference. Verduzco is the Chair for the 2018 De Lange Conference on Bioelectronics and the first Gordon Research Conference on Bioelectronics, to be held in 2019.
Contact Prof. Yan Yao yyao4 at Central.UH.EDU<mailto:yyao4 at Central.UH.EDU>  if you would like to meet with Dr. Verduzco.
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