Molecular motion in a spreading precursor film.
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.
Xu
Hui
H
Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599-3290, USA.
Shirvanyants
David
D
Beers
Kathryn
K
Matyjaszewski
Krzysztof
K
Rubinstein
Michael
M
Sheiko
Sergei S
SS