title: Molecular motion in a spreading precursor film.
abstract: Spreading of a polymer drop on a solid substrate was monitored with molecular resolution. Three characteristic rates, i.e., the spreading rate of the precursor film D(spread)=(3.9+/-0.2)x10(3) nm(2)/s, the flow-induced diffusion rate of molecules within the film D(induced)=1.3+/-0.1 nm(2)/s, and the thermal diffusion coefficient of single molecules D(therm)</=0.10+/-0.03 nm(2)/s, were independently measured. Since D(spread)>>D(induced), the plug flow of polymer chains was identified as the main mass-transport mechanism of spreading with an insignificant contribution from the molecular diffusion.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599-3290, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: David
authors.initials: D
authors.lastname: Shirvanyants
authors.forename: Kathryn
authors.initials: K
authors.lastname: Beers
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Matyjaszewski
authors.forename: Michael
authors.initials: M
authors.lastname: Rubinstein
authors.forename: Sergei S
authors.initials: SS
authors.lastname: Sheiko