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Ralph H.
Colby
Professor of Materials Science and Engineering
309 Steidle Building
(814) 863-3457
colby@matse.psu.edu
http://felix.metsce.psu.edu/Colby/index.html |
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Biographical
Sketch:
Ralph H. Colby received his B.S. in Materials Science
and Engineering from Cornell University in 1979. After working
for two years at the General Electric Company in rheology
research and process development, he attended graduate school
at Northwestern University, where he received his M.S. and Ph.D. in
Chemical Engineering in 1983 and 1985. Graduate research
focused on rheology of linear polybutadiene melts and solutions,
and included 15 months as a visiting scholar in the Exxon
Research and Engineering Company, Corporate Research - Science
Laboratories. He then worked for ten years at the Eastman
Kodak Company in their Corporate Research Laboratories. Rheology
research areas over these ten years included linear polymer
melts and solutions, miscible
polymer blends, block copolymers, randomly branched polymers,
polymer gels, liquid crystalline polymers, polyelectrolytes,
proteins, surfactants and colloidal suspensions.
In 1995, Dr. Colby was hired as Associate Professor of Materials
Science and Engineering at the Pennsylvania State University
and was promoted to Professor in 2000. He teaches a very
demanding undergraduate course on Polymer Rheology and Processing
and continues to use rheological experiments to probe the
dynamics of polymers and other complex fluids. Dr.
Colby has over 100 publications and published a textbook Polymer
Physics in 2003. |
Research
Interests:
• Proteins
• Polyelectrolytes
• Ionomers
• Liquid crystalline polymers
• Block copolymers
• Miscible polymer blends
• Branched polymers
• Networks
• Glass-forming liquids
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Surfactants and colloidal suspensions |
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Area of Research
Professor
Colby’s research group is interested
in a molecular-level understanding of dynamics in interesting
liquids. Polymer liquids are good examples because
they are viscoelastic: While polymer liquids do
flow, they have considerable elastic character. Other
examples include many “complex fluids” such as
liquid crystals and surfactants. The Colby group measures
the dynamics of these liquids using mechanical rheology and
dielectric spectroscopy and also characterizes the liquid
structure using neutron and x-ray scattering and optical
methods. This is classical materials science research
on structure-property relations but at the same time is highly
innovative because it is applied to the liquid state!
One nice example is the study of ion transport in ionomer membranes. Ionomers are polymers with one type of ion covalently bonded to the chain and are ‘single-ion conductors’ in that only the unattached counterions can move rapidly in response to an applied electric field. Designing ionomers for facile ion transport is challenging and the Colby group is attacking this problem with ab initio calculations of ion interactions that guides our synthesis of new ionomers. We use small-angle X-ray scattering (picture above), mechanical rheology and dielectric spectroscopy to understand what the ions are doing in these new ionomers. We quantify the temperature dependences of the fraction of ions in ion pairs, conducting triple ions and quadrupoles, for different ionomers with various counterions (figure below).
There are a great many interesting liquids known in the world today and more are being discovered every day. The Colby group’s mission is to understand in detail the structure-property relations of all interesting liquids. This is a great challenge and as such, only the best highly motivated students are able to participate in this exciting mission. |
Technologies
Impacted By Research:
Polymer dynamics, characterized by rheology, plays a vital role in solution and melt processing of polymers. Ion-containing polymers are a poorly understood class of materials that are potentially very important for actuators, sensors, separators between the electrodes of advanced batteries and fuel cell membranes. |
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Articles and Publications:
1. D. Fragiadakis, S. Dou, R. H. Colby and J. Runt, Molecular Mobility, Ion Mobility, and Mobile Ion Concentration in Poly(ethylene oxide)-based Polyurethane Ionomers, Macromolecules 41, 5723 (2008).
2. R. H. Colby, Polyelectrolyte Gels: Ionic Partners Split Up, Nature Materials 6, 401 (2007).
3. S. Dou, S. Zhang, R. J. Klein, J. Runt and R. H. Colby, Synthesis and Characterization of Poly(ethylene glycol)-based Single-Ion Conductors, Chem. Mater. 18, 4288 (2006).
4. F. Bordi, C. Cametti and R. H. Colby, Dielectric Spectroscopy and Conductivity of Polyelectrolyte Solutions, J. Phys.: Condens. Matt. 16, R1423 (2004).
5. A. V. Dobrynin, R. H. Colby and M. Rubinstein, Polyampholytes, J. Polym. Sci., Polym. Phys. 42, 3513 (2004).
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