Letter pubs.acs.org/macroletters
Cite This: ACS Macro Lett. 2018, 7, 834−839
Anomalous Confinement Slows Surface Fluctuations of Star Polymer Melt Films Fan Zhang,† Qiming He,†,# Yang Zhou,† Suresh Narayanan,‡ Chao Wang,§ Bryan D. Vogt,§ and Mark D. Foster*,† ACS Macro Lett. Downloaded from pubs.acs.org by UNIV OF CALIFORNIA SANTA BARBARA on 06/25/18. For personal use only.
†
Department of Polymer Science and §Department of Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States ‡ X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States S Supporting Information *
ABSTRACT: The unusually large film thickness at which confinement effects manifest themselves in surface fluctuations of unentangled four-arm star polymers has been defined using film thicknesses from 10Rg to 107Rg. For 15k four-arm star polystyrene (SPS), confinement appears at a thickness between 112 nm (40Rg) and 72 nm (26Rg), which is remarkably larger than the thicknesses at which confinement appears for unentangled 6k linear (
