pH-responsive aqueous/LC interfaces using SGLCP-b-polyacrylic acid block copolymers
Abstract
Block copolymers that combine a side-group liquid crystalline polymer (SGLCP) block and a pH-responsivehydrophilic block, poly(acrylic acid) (PAA), are shown to confer pH-dependent anchoring of the director orientation at the aqueous/LC interface. The SGLCP block, poly(4-cyanobiphenyl-4-oxyundecylacrylate), was chosen based on its ability to influence the director field of the 5CB (4-cyano-4'-pentylbiphenyl). At low pH the PAA block collapses and the inherent, planar alignment tendency of 5CB at a water interface prevails. As pH increases, the polyelectrolyte block becomes increasingly charged and expands, producing a change to homeotropic anchoring. The change in anchoring occurs as quickly as the buffer can be changed (within ~2 s) and is reversible, with a response that is repeatable over as many cycles as were tested (approximately 20 cycles). The polymer-mediated anchoring persists for 6 days, indicating that the SGLCP block secures the self-assembled layer on the 5CB, even under conditions that cause repulsive interactions among the PAA blocks. Thus, SGLCP blocks can translate conformational changes of a responsive hydrophilic block into rapid, reversible changes in the director field
Additional Information
© 2010 The Royal Society of Chemistry. Received 15th December 2009, Accepted 22nd February 2010. First published as an Advance Article on the web 26th March 2010.Attached Files
Published - Lee2010p9955Soft_Matter.pdf
Supplemental Material - b926461b.mpg
Supplemental Material - b926461b.pdf
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Additional details
- Eprint ID
- 18331
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- CaltechAUTHORS:20100517-153103244
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2010-05-24Created from EPrint's datestamp field
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2021-11-08Created from EPrint's last_modified field