A Direct Comparison of Surface and Bulk Chain-Relaxation in Polystyrene
Wen-Li Wu, S Sambasivan, C M. Wang, William E. Wallace, Jan Genzer, Daniel A. Fischer
Near-edge x-ray absorption fine structure (NEXAFS) spectroscopy was used to meausre simultaneously the relaxation rates of polystyrene (PS) molecules at the free surface and in the bulk. The samples were uniaxially stretched and annealed at temperatures below the bulk glass transition temperature of PS. The surface and bulk chain relaxation was monitored by measuring the partial-electron and the fluorescence NEXAFS yields, respectively, both parallel and perpendicular to the stretching direction. The decay of the optical birefringence was also measured to provide an independent measure of the bulk relaxation. Relaxation of PS chains was found to occur significantly faster on the surface relative to the bulk. The magnitude of the surface glass transition temperature suppression over the bulk was estimated to be 18 degrees based on the difference in the relaxation rates of the surface and bulk and the temperature dependence of the rates.
, Sambasivan, S.
, Wang, C.
, Wallace, W.
, Genzer, J.
and Fischer, D.
A Direct Comparison of Surface and Bulk Chain-Relaxation in Polystyrene, European Physical Journal E, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852179
(Accessed December 3, 2023)