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Shear Aligning Properties of a Main-Chain Thermotropic Liquid Crystalline Polymer

Zhou, Wei-Jun and Kornfield, Julia A. and Burghardt, Wesley R. (2001) Shear Aligning Properties of a Main-Chain Thermotropic Liquid Crystalline Polymer. Macromolecules, 34 (11). pp. 3654-3660. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20170710-150255505

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Abstract

We report the first direct, quantitative measurements of the shear aligning properties of a main-chain thermotropic liquid crystalline polymer (LCP). We find that a model thermotrope with alternating mesogen and spacer structure is of the shear aligning type throughout its nematic range. The director rotates uniformly in the shear flow toward the Leslie alignment angle as probed by in situ flow conoscopy. The Leslie alignment angle becomes progressively closer to the flow direction as temperature decreases, corresponding to a decrease of the tumbling parameter λ with increasing order parameter S. Our measurements of λ(S) enable direct comparison with predictions from molecular models, which predict that shear alignment prevails in the limit of flexible nematic chains. This is in direct contrast to rodlike lyotropic LCPs for which director tumbling is the rule.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ma0018493DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma0018493PublisherArticle
ORCID:
AuthorORCID
Kornfield, Julia A.0000-0001-6746-8634
Additional Information:© 2001 American Chemical Society. Received October 27, 2000. Publication Date (Web): April 26, 2001. Financial support was provided by the Air Force Office of Scientific Research Liquid Crystal-MURI (Grant F49620-97). We thank Prof. Peter Palffy-Muhoray of Kent State University for assistance with liquid crystal alignment.
Funders:
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)F49620-97
Issue or Number:11
Record Number:CaltechAUTHORS:20170710-150255505
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170710-150255505
Official Citation:Shear Aligning Properties of a Main-Chain Thermotropic Liquid Crystalline Polymer Wei-Jun Zhou, Julia A. Kornfield, and Wesley R. Burghardt Macromolecules 2001 34 (11), 3654-3660 DOI: 10.1021/ma0018493
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78910
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:10 Jul 2017 22:06
Last Modified:03 Oct 2019 18:13

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