Flow-enhanced epitaxial ordering of brush-like macromolecules on graphite

TitleFlow-enhanced epitaxial ordering of brush-like macromolecules on graphite
Publication TypeJournal Article
Year of Publication2006
AuthorsH Xu, SS Sheiko, D Shirvanyants, M Rubinstein, KL Beers, and K Matyjaszewski
JournalLangmuir : the Acs Journal of Surfaces and Colloids
Pagination1254 - 1259
Date Published01/2006
Abstract

Long-range orientational order in monolayers of brush-like macromolecules was achieved during spreading of a polymer melt on the surface of highly oriented pyrolytic graphite. The combination of wetting-induced flow and epitaxial adsorption of poly(n-butylacrylate) side chains on graphite led to the formation of large domains of uniaxially oriented rodlike molecules. The domain size varied from ca. 1 to 10 microm which is noticeably larger than the submicrometer-sized mosaic domains typically observed upon adsorption from solution. The increase in the degree of order is attributed to the flow-enhanced diffusion of the macromolecules within spreading monolayers which facilitates the epitaxial alignment of the large macromolecules. The diffusion coefficient was shown to increase linearly with the spreading rate. Even though the ordering occurred during flow, no correlation was observed between the molecular orientation and the flow direction. Thus, the role of the flow was not to induce the molecular orientation but to facilitate the intrinsic ordering process. This finding can inspire and lead to new strategies for constructing large scale ordered structures on surfaces.

DOI10.1021/la052163c
Short TitleLangmuir : the Acs Journal of Surfaces and Colloids