title: Mobility of polymer chains confined at a free surface.
abstract: Dynamic secondary ion mass spectrometry was used to investigate the chain mobility of polystyrene (MW ranging from 4.3 to 957 kg/mol) at the free surface. The data show that the diffusion coefficient was reduced relative to the bulk value within a distance, d < or = 4R(g), from the surface and scaled as 1/N(2.5) at fixed d. These results are in excellent agreement with self-consistent field calculations of the surface segmental distribution and provide the first direct confirmation of various theoretical models that predict asymmetric segmental fluctuation which arises from surface induced orientation of polymer chains.
authors.affiliation: Department of Materials Science and Engineering, State University of New York, Stony Brook, New York 11794-2275, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Pu
authors.forename: M H
authors.initials: MH
authors.lastname: Rafailovich
authors.forename: J
authors.initials: J
authors.lastname: Sokolov
authors.forename: D
authors.initials: D
authors.lastname: Gersappe
authors.forename: T
authors.initials: T
authors.lastname: Peterson
authors.forename: W L
authors.initials: WL
authors.lastname: Wu
authors.forename: S A
authors.initials: SA
authors.lastname: Schwarz