Molecular Orientation of Single and Two-Armed Monodendron Semifluorinated Chains on Soft and Hard Surfaces Studied Using NEXAFS

Published

August 1, 2000

Author(s)

Jan Genzer, E Sivaniah, E K. Kramer, J G. Wang, M Xiang, K Char, Christopher K. Ober, Robert A. Bubeck, Daniel A. Fischer, M Graupe, R Colorado, O E. Shmakova, T R. Lee

Abstract

Near-edge absorption fine structure (NEXAFS) measurements are used to probe the molecular orientation of semifluorinated (SF) mesogens, -(CH₂)x(CF₂)yF, which are attached to I) the isoprene backbone of polyisoprene or a styrene-isoprene diblock copolymer (soft substrate), and ii) a Au-covered solid substrate via a thiol link (hard substrate). The SF groups on both surfaces are oriented and on average are tilted from the sample normal. The tilt angle, <τF-helix>, of the fluorinated part of the SF group on each substrate is determinedexclusively by the combination of x and y, increasing with increasing x and with decreasing y. Moreover, <τF-helix> is found to be independent of the surface topology (flat surfaces vs. surfaces covered with holes or islands of the copolymer), casting solvent, and the architecture of the SF group (single vs. 2-armed monodendron). Comparing the orientation of the SF groups on both substrates reveals that (τ F-helix> is approximately 14 higher on the soft substrate.

Citation

Macromolecules

Volume

33

Issue

No. 16

Pub Type

Journals

Keywords

diblock copolymers, flurocrbons, low surface energy materials, NEXAFS, polymers

Citation

Genzer, J. , Sivaniah, E. , Kramer, E. , Wang, J. , Xiang, M. , Char, K. , Ober, C. , Bubeck, R. , Fischer, D. , Graupe, M. , Colorado, R. , Shmakova, O. and Lee, T. (2000), Molecular Orientation of Single and Two-Armed Monodendron Semifluorinated Chains on Soft and Hard Surfaces Studied Using NEXAFS, Macromolecules (Accessed December 13, 2024)