Purdue University School of Chemical Engineering Graduate Seminar Series Dr. Alan W. Weimer H.T. Sears Memorial Professor Executive Director, Colorado Center for Biorefining and Biofuels Department of Chemical Engineering and Biological Engineering University of Colorado-Boulder "Functionalization of Fine Particles by Atomic/ Molecular Layer Deposition (ALD/MLD)" March 8, 2011 3:30 - 4:30 p.m. FRNY G140 Abstract: The functionalization of fine primary particles, including nanoparticles and nanotubes, is easily carried out using sequential self-limiting surface reactions. The self-limiting reactions result in the deposition of atomic or molecular layers, i.e. ALD or MLD. This functionalization process, referred to as Particle ALD/MLD, can be used to deposit conformal and pinhole-free films of refractory oxides, non-oxides, metals, and hybrid polymer-based materials, among others. Fluidized bed reactors are well suited for large scale operations. In this process, the particles are normally fluidized under reduced pressure conditions using an inert gas. Precursor doses can be delivered to the bed of particles sequentially and, in most cases, can be utilized at nearly 100% efficiency without precursor breakthrough and loss. The progress of the coating process can be monitored continuously using an in-line downstream mass spectrometer. The ability to use precursors with efficiencies approaching 100% opens the door for a unique opportunity to utilize precursors that previously might have been considered to be too expensive. Fluidized beds containing particles comprising hundreds of thousands, even millions of m^2 of surface area can be coated efficiently. The dose times depend on the amount of surface area required to be coated and the flow rate of the precursor into the fluidized bed. Although dose times could potentially be very long for coating millions of m^2 of particles, i.e. minutes to hours, the efficient use of the precursor to place nearly perfect films on primary particles makes Particle ALD/MLD the low cost and potentially only process that can cost-effectively functionalize high surface area ultra-fine particles. Particle ALD/MLD has been demonstrated to place films on primary nanoparticles as small as 10 nm as well as on nanotubes having surface areas approaching 1000 m2/g and within the porous structure of polymeric materials having porosity near 95%. Physical, optical, electrical, and magnetic properties of the particles can be controlled in order to passivate, activate, or is some manner functionalize the particles. Bio: Al Weimer, H.T.Sears Memorial Professor of Chemical and Biological Engineering, joined the faculty of the University of Colorado after a 16 year career with the Dow Chemical Company. He was named Dow Research Inventor of the Year in 1993 and received Dow's "Excellence in Science Award" in 1995 for commercializing high temperature processing to produce advanced materials. He was named University of Colorado Inventor of the Year in 2004 and received both the campus wide and the College of Engineering and Applied Science Faculty Research Awards in 2005. He is recipient of the 2005 DOE Hydrogen Program R&D Award, the 2009 AIChE Thomas Baron Award in Fluid-Particle Systems and will receive the 2010 AIChE Excellence in Process Development Research Award in November. His former students have co-founded two spin-off companies out of his university laboratory. He is named inventor on 24 issued U.S. Patents and author of over 100 peer-reviewed publications. He received a 2004 R&D 100 Award for his invention and commercial development using atomic layer deposition to functionalize fine particles (i.e. Particle ALD). At Colorado, Al teaches the capstone design course sequence while directing 12 Ph.D. students and 4 Postdocs. He is currently working on the 6th edition of the famous Peters and Timmerhaus text "Plant Design and Economics for Chemical Engineers".