Sequence of Rubbing-Induced Molecular Segmental Reorientations in the Nanoscale Film Surface of a Brush Polymer Rod

The Journal of Physical Chemistry. B
Boknam ChaeMoonhor Ree

Abstract

Poly(p-phenylene-3,6-bis(4-(n-butoxy)phenyloxy)pyromellitimide) (C4-PMDA-PDA PI), a well-defined model brush polymer composed of a rodlike polymer backbone with two bristles per repeat unit, was the first reported polyimide to align liquid crystals perpendicular to the rubbing direction at the rubbed film surface. In the present study, we used polarized infrared (IR) spectroscopy and 2D correlation analyses of the resulting IR spectra to study nanoscale films of C4-PMDA-PDA PI rubbed at various rubbing densities. The results of these studies allowed us to establish the nature and sequence of the rubbing-induced segmental reorientations that occur in the polymer molecules at the film surface. The rubbing process was found to reorient the fully rodlike polymer backbones and the n-butyl bristle end groups such that they lay parallel to the rubbing direction. In contrast, rubbing caused the phenyloxy bristle units to reorient to a direction perpendicular to the rubbing direction. These reorientations of the polymer's main chain and bristles became more pronounced with increasing rubbing density, and the rubbing process had a greater effect on the polymer's main chains than on the bristles. The rubbing-induced reorientations of the ...Continue Reading

References

Sep 1, 1993·Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics·D JohannsmannY R Shen
Feb 1, 1994·Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics·V G Nazarenko, O D Lavrentovich

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