Michael Rubinstein
J. Ross MacDonald Professor of Chemistry
The University of North Carolina at Chapel Hill

"Spreading of Molecular Brushes"

The abstract:

Molecular brushes are comb polymers with high density of side branches. Unique conformations of these molecules in a pre-wetting layer allow direct visualization by atomic force microscope (AFM). Detailed images of individual molecules spreading along the surface enable critical evaluation of theories of chain dynamics in polymer monolayer. Molecular brushes with high density of branches along polymer backbone act as pressure sensors because their thickness and therefore number density in the pre-wetting layer changes with pressure. (Phys. Rev. Lett. 93, 20603, 2004) At a certain critical pressure brushes undergo conformational transition. This transition of molecular brushes leads to fingering instability in the pre-wetting layer. (Phys. Rev. Lett. 94, 237801, 2005) The tension in the backbone can be high enough to cause adsorption-induce self-destruction of these molecules. (Nature 440, 191-194, 2006)