title: Creeping friction dynamics and molecular dissipation mechanisms in glassy polymers.
abstract: The dissipation mechanism of nanoscale kinetic friction between an atomic force microscopy tip and a surface of amorphous glassy polystyrene has been studied as a function of two parameters: the scanning velocity and the temperature. Superposition of the friction results using the method of reduced variables revealed the dissipative behavior as an activated relaxation process with a potential barrier height of 7.0 kcal/mol, corresponding to the hindered rotation of phenyl groups around the C-C bond with the backbone. The velocity relationship with friction F(v) was found to satisfy simple fluctuation surface potential models with F proportional to const-ln(v) and F proportional to const-ln(v)2/3.
authors.affiliation: Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Sills
authors.forename: René M
authors.initials: RM
authors.lastname: Overney