Local Viscosity and Environment on the Nanometer Scale

154 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2002.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.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD