AVS 66th International Symposium & Exhibition
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP10
Surface Photovoltage Studies of UV-driven Hydrophilic Flipping in Polysulfone Thin Films

Tuesday, October 22, 2019, 6:30 pm, Room Union Station B

Session: Surface Science Poster Session
Presenter: John Reeks, Texas Christian University
Authors: J.M. Reeks, Texas Christian University
N. Posinski, Texas Christian University
T. Haun, Home School High School Student
H. Hilton, Texas Christian University
A. Dorward, Washington and Lee University
E. Bormashenko, Ariel University, Israel
Y.M. Strzhemechny, Texas Christian University
Correspondent: Click to Email
It has been shown in previous studies that hydrophobic surfaces of polysulfone flip to become hydrophilic upon exposure to UV radiation. The exact mechanisms driving this phenomenon are not completely understood. We suggest that elucidation of the surface charge transport phenomena of the as-deposited and UV-irradiated polysulfone could explicate the conversion mechanism and thus contribute to the improved applications of polysulfone on the micro- and nanoscale for novel applications in microfluidics and biophysics. To investigate the UV-driven hydrophilic flipping we performed surface photovoltage (SPV) studies on thin polysulfone films spin-cast on silicon substrates. Since SPV is sensitive to buried interfaces, the resulting spectra are expected to be comprised of features originating not only from the polysulfone films, but also from the silicon wafer and the silicon oxide layer beneath the polymer films. Thereby, to identify the signal germane to polysulfone proper, we employed in our studies polysulfone films of varying and controllable thicknesses to be probed with SPV spectroscopy as well as SPV transient experiments. SPV measurements on Si substrates acted as a control for comparison. Our experiments revealed that SPV yield is significantly affected by the polysulfone films. In particular, we observed significant polarity reversal in the SPV transients in the samples with polysulfone films, whereas SPV spectra indicated transitions at 1.1-1.5 eV appearing in the polysulfone layers. We also report on the comparison of the SPV response in the as-deposited and UV-irradiated polysulfone samples.