The W. Allan Powell Lectureship
Dr. Timothy Swager
Timothy M. Swager is the John D. MacArthur Professor of
Chemistry and the Head of the Department of Chemistry at the
Massachusetts Institute of Technology. A native of Montana,
he received a BS from Montana State University and a Ph.D.
from the California Institute of Technology. After a
postdoctoral appointment at MIT in the laboratory of Mark S.
Wrighton, he was on the chemistry faculty at the University
of Pennsylvania from 1990-1996. He moved to MIT in July of
1996 as a Professor of Chemistry. He has published about 250
peer-reviewed papers, 70 proceedings, and 5 book chapters
and serves on multiple editorial boards. His research
interests are in design, synthesis, and study of
organic-based electronic, sensory, and liquid crystalline
materials.
In the field of liquid crystals he developed new designs
based upon shape complementarity to generate specific
interactions between molecules and has recently developed
fundamental mechanisms for increasing the order in liquid
crystals by a new mechanism referred to as minimization of
free volume. Swager=s research in electronic polymers has
been directed at the demonstration of new conceptual
approaches to the construction of sensory materials. In
particular, he has developed conjugated polymer sensory
transduction schemes that translate molecular recognition
events into readily measured signals. The fundamental tenet
of this research is that the cooperative nature of these
materials produces enhancements in observable signals
relative to monomeric analogs. Swager has shown this
amplification to be general and applicable to any signal,
which is dependent upon the transport properties of the
system. Materials and methods from the Swager laboratory are
the enabling technology for the explosive detectors that
have become the flagship products of ICx Technologies Inc.
These sensors have demonstrated unprecedented sensitivities
for the detection of the explosive TNT. Related technologies
are under commercial development for the detection of
chemical weapons, toxic industrial chemicals, and biological
molecules. Other areas impacted by Swager=s molecular and
polymer designs include ultra-stable low dielectric constant
materials for use as interlayer dielectrics, polymer
actuators, and novel molecular probes for medical
diagnostics.
Dr. Swager has received a number of awards and honors
including: Election to the National Academy of Science 2008,
Fellow of the American Academy of Arts and Sciences 2006,
Christopher Columbus Foundation Homeland Security Award
2005, The Carl S. Marvel Creative Polymer Chemistry Award
(ACS-Polymer Div) 2005, Clare Hall Visiting Fellow (U.
Cambridge, England) 2005, Vladimir Karapetoff Award (MIT)
2000, Cope Scholar Award (ACS) 2000, Union Carbide
Innovation Recognition Award 1997-8, Philadelphia Section
Award (ACS) 1996, Camille Dreyfus Teacher-Scholar 1995-1997.
"Polymer Electronics for
Chemical and Biological Sensors"
This lecture will describe the conceptual design and
optimization of chemical/biological sensors based upon
conjugated polymers (CPs) and carbon nanotubes (CNTs). The
ability of a CP to produce amplification in a fluorescence-
or resistance-based chemosensor stems from its ability to
transport optical excitations or electrical charge,
respectively, over large distances. These transport
properties provide the increased sensitivity and versatility
of CPs and CNTs over small-molecule chemosensors. By adding
new functional diversity to CPs and CNTs chemoresistive
properties have been realized. In fluorescence sensors, the
migration of an optical excitation increases the probability
of an encounter with an occupied binding site. We originally
demonstrated this scheme making use of analyte induced
quenching and have also demonstrated how local reductions in
the polymers bandgap produce wavelength shifts in emission.
To impart recognition to our polymers we have made use of a
variety of molecular recognition schemes, assemblies, and
reactions. Recent applications of amplifying polymers in
biosensory schemes will be discussed. A number of different
methods can be used to impart analyte selectivity to
electronic polymer sensors. These involve designed
receptors, modifications to the energy levels of the
polymers, and coupling to other key reactions. The latest
results in these directions will be described.