|
9:00 a.m.-10:30 a.m.
Kim Engineering Building Lecture Hall (Rm 1110)
For More Information:
Peter Kofinas
301 405 7335
kofinas@umd.edu
Robert E. Cohen, Professor of Chemical Engineering
Massachusetts Institute of Technology
Superhydrophobic surfaces that display water contact angles greater than 150o with low contact angle hysteresis are becoming commonplace in the materials community. Microscopic pockets of air trapped beneath the high surface tension (γlv = 72mN/m) water droplets lead to a composite solid-liquid-air interface in thermodynamic equilibrium. Previous experimental and theoretical work suggests that it should not be possible to form similar fully-equilibrated composite interfaces with drops of low surface tension liquids such as alcohols or alkanes (e.g. pentane: γlv = 16 mN/m). In this lecture I will discuss novel surfaces that possess the required combination of re-entrant topographical texture and surface chemistry to support strongly metastable composite solid-liquid-air interfaces for any liquid. Quantitative design parameters will be introduced to guide the development of these novel omniphobic surfaces. For a given feature size R, two independent design parameters [surface chemistry as revealed in the equilibrium contact angle θ, and texture spacing, embodied in the dimensionless spacing ratio D*= (R+D)/R] can be used to develop surfaces with desirably large values of apparent contact angle (θ*) and robustness of the metastable composite interface. Most revealing is the scaling of the composite interface robustness which indicates clearly why, in the consideration of self-similar arrangements of topographical surface features, ‘smaller is better’ for producing surfaces that resist wetting by low energy liquids. Examples that have been realized to date include lithographically fabricated features in silicon, randomly deposited electro spun fiber mats, dip-coated textiles and wire meshes.
Robert E. Cohen
Bob Cohen studied at Cornell University (BS), Caltech (MS and PhD) and Oxford University (Postdoc) prior to joining the MIT faculty in 1973. He founded MIT’s Program in Polymer Science and Technology in 1984 and in 2009 he reassumed the role of PPST Director. He has also served MIT in the capacity of Associate Chair of the Faculty (1989-1991). He was the architect of MIT’s unique Doctoral Program in Chemical Engineering Practice, and he has chaired that program’s steering committee from its official launch in 1999 until the present time. He also chaired the Chemical Engineering department’s Committee on Graduate Studies from 1992 through 2001. He is in his tenth year of continuous leadership of the $60million DuPont/MIT Alliance. Bob currently holds the endowed Raymond A. and Helen E. St. Laurent Professorship in the Chemical Engineering department.
Bob has been active in professional society activities including service to the American Institute of Chemical Engineers as the Chair of Polymer Programming (1993-1996) and as a Director of the Materials Division (1998-2001). He was a consulting editor for the American Institute of Physics book series on Polymers and Complex Fluids (1992-1996), currently serves on the editorial advisory boards of several polymer science journals, and is North American editor for the Journal of Polymer Engineering. At MIT he has received the DuPont Young Faculty Award (1974), the Edgerton Assistant Professor Award (1975-1977) and the Bayer term chair (1988-1995). In 1999 he received the GenCorp signature university award for polymer research. In August of 2006 he became the first recipient of the MIT School of Engineering’s Capers and Marion McDonald Award for Excellence in Mentoring and Advising. He received the Charles M.A. Stine Award from the Materials Division of the American Institute of Chemical Engineers in 2000, and he was named a Fellow of AIChE in 2005. In 2004 Bob was elected Fellow of the American Physical Society. He was a recipient of a Camille and Henry Dreyfus Teacher-Scholar Award (1987) and has presented numerous invited lectures including the Robert W. Vaughan Memorial Lecture at Caltech (1984), the Shell Distinguished Lectureship at Northwestern (1996), and the Bayer Lectureship at the University of Pittsburgh (2009).
His 300 peer-reviewed publications and 25 patents reflect interests in polymer structure/property relationships. He maintains a program of synthetic polymer chemistry to support the experimental structure/property work. Students from his research group have developed successful careers in a variety of professional settings, ranging from research centers of Fortune 500 companies and government laboratories to self-founded startups. Eleven of the sixty five doctoral students who have studied under his direction hold tenured or tenure-track faculty positions, ten in the USA and one abroad. Based on a set of patents produced in his laboratory on the topic of polymer surface modification, Bob co-founded MatTek Corporation (http://www.mattek.com) in 1985. He has served on the board of trustees of the Advent School in Boston (1995-1999) and Kiser Research, Inc., in Washington D.C (1988-1990). He is currently a member of the board of directors of the William and Mary Greve Foundation in New York City and MatTek Corporation in Ashland, MA. He serves on External Advisory Committees for the Department of Chemical Engineering at Columbia University and the Nanoscale Science and Engineering Center at the University of Wisconsin. He is on the scientific advisory boards of Zyxol, Ltd. (Oxford UK) and Savya, Inc. (Los Angeles).
This Event is For: Graduate • Faculty • Post-Docs
|
