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Shear-Induced Alignment of Smectic Side Group Liquid Crystalline Polymers

Rendon, Stanley and Burghardt, Wesley R. and Auad, Maria L. and Kornfield, Julia A. (2007) Shear-Induced Alignment of Smectic Side Group Liquid Crystalline Polymers. Macromolecules, 40 (18). pp. 6624-6630. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20170724-101025537

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Abstract

Large amplitude oscillatory shear (LAOS) is frequently capable of generating macroscopic alignment from an initially random orientation distribution in ordered polymer fluids. Side-group liquid crystalline polymers are of special interest in that the flow field may couple differently to the polymer backbone and the mesogen ordering. We report combined rheological and in situ X-ray scattering investigations of LAOS-induced alignment in smectic side-group LCPs. Synchrotron X-ray scattering is used to study orientation development using a rotating disk shear cell in which orientation is tracked within the flow-vorticity (1−3) plane. In all cases, we find that shear promotes anisotropic orientation states in which the lamellar normal tends to align along the vorticity direction of the shear flow (“perpendicular” alignment). We examine the effects of shear strain amplitude and polymer backbone molecular weight on the ability of LAOS to induce alignment. Rheological measurements of the dynamic moduli reveal that large amplitude shearing in the smectic phase causes a notable decrease in the modulus. X-ray and rheological data demonstrate that increasing strain promotes higher degrees of orientation, while increasing molecular weight impedes development of smectic alignment.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ma062912cDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma062912cPublisherArticle
ORCID:
AuthorORCID
Kornfield, Julia A.0000-0001-6746-8634
Additional Information:© 2007 American Chemical Society. Received 19 December 2006. Published online 14 August 2007. Published in print 1 September 2007. We thank Michael. D. Kempe for synthesizing the SGLCPs used in this investigation. We gratefully acknowledge financial support from the Air Force Office of Scientific Research (AFOSR)-LC MURI, the National Science Foundation (Grants DMI-0099542 and DMI-0521823), Fundación Antorchas (Argentina), and CONICET (Argentina). X-ray scattering experiments were conducted at the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) Synchrotron Research Center located at Sector 5 of the Advanced Photon Source of Argonne National Laboratory. DND-CAT is supported by the E.I. DuPont de Nemours & Co., the Dow Chemical Company, and the National Science Foundation through Grant DMR-9304725 and the State of Illinois through the Department of Commerce and the Board of Higher Education Grant IBHE HECA NWU 96. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Basic Energy Sciences, Office of Energy Research, under Contract No. W-31-102-Eng-38.
Funders:
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
NSFDMI-0099542
NSFDMI-0521823
Fundación AntorchasUNSPECIFIED
Consejo Nacional de Investigaciones Científicas y Técnicas (CONCIET)UNSPECIFIED
E.I. DuPont de Nemours & Co.UNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
NSFDMR-9304725
Illinois Department of CommerceIBHE HECA NWU 96
Department of Energy (DOE)W-31-102-Eng-38
Illinois Board of Higher EducationUNSPECIFIED
Issue or Number:18
Record Number:CaltechAUTHORS:20170724-101025537
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170724-101025537
Official Citation:Shear-Induced Alignment of Smectic Side Group Liquid Crystalline Polymers Stanley Rendon, Wesley R. Burghardt, Maria L. Auad, and Julia A. Kornfield Macromolecules 2007 40 (18), 6624-6630 DOI: 10.1021/ma062912c
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79295
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:24 Jul 2017 19:44
Last Modified:03 Oct 2019 18:18

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