Local Viscosity and Environment on the Nanometer Scale
Jeon, Sangmin
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https://hdl.handle.net/2142/82730
Description
Title
Local Viscosity and Environment on the Nanometer Scale
Author(s)
Jeon, Sangmin
Issue Date
2002
Doctoral Committee Chair(s)
Granick, Steve
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
New optical setup for two photon excitation time-resolved fluorescence anisotropy and lifetime measurements was built and used to understand the local environment and viscosity. The rotational correlation time constants by the fluorescence anisotropy provide the information on the hydrodynamic volume and local viscosity near the probe. Instead, the fluorescence lifetime does the local environment near the probe such as pH, temperature and polarity of the medium. Based on these fluorescence measurements, it was shown that the motions of DNA and polystyrene at the surface were more retarded than those in bulk. Also, local viscosity of the pluronic polymer which shows sol to gel phase transition was compared to the bulk viscosity near the transition temperature and the local viscosity change is much smaller than bulk viscosity. With the combination of dielectric measurement, the motion of polymer chains and local viscosity were separately measured for the ion conductive polypropylene oxide.
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