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Effect of Mesophase Order on the Dynamics of Side Group Liquid Crystalline Polymers

Auad, Maria L. and Kempe, Michael D. and Kornfield, Julia A. and Rendon, Stanley and Burghardt, Wesley R. and Yoon, Kyunghwan (2005) Effect of Mesophase Order on the Dynamics of Side Group Liquid Crystalline Polymers. Macromolecules, 38 (16). pp. 6946-6953. ISSN 0024-9297. doi:10.1021/ma050551f.

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Rheology and X-ray scattering were employed to probe the viscoelastic properties and structural transitions of model cyano-biphenyl-based side-group liquid−crystalline polymers (SGLCPs) with molecular weights ranging from 91 to 1900 kg/mol. Temperature-dependent rheological data show a rapid change in dynamics over a small temperature range. Small-angle X-ray scattering reveals these changes to be associated with an isotropic to smectic transition with an appreciable biphasic region. The presence of a biphasic region is attributed to inhomogeneity in chain structure resulting from incomplete attachment of mesogens to every monomeric unit in the SGLCP polymer. While isotropic and smectic phase data may be separately time−temperature shifted to create master curves for the individual phases, we argue against attempts to achieve superposition between the two phases in the high-frequency regime, since smectic ordering may not simply slow the dynamics but also increase the modulus of the sample. Molecular weight has a strong influence on rheology in the isotropic phase, where an entanglement plateau emerges; however, the smectic-phase rheology is dominated by the layer structure and is fairly insensitive to molecular weight.

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Kornfield, Julia A.0000-0001-6746-8634
Additional Information:© 2005 American Chemical Society. Received 15 March 2005 Published online 16 July 2005 Published in print 1 August 2005 We gratefully acknowledge financial support from the Air Force Office of Scientific Research (AFOSR)-LC MURI (f4962-97-1-0014), Fundación Antorchas (Argentina), CONICET (Argentina), and the National Science Foundation (DMI-0132519). 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.
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)f4962-97-1-0014
Fundación AntorchasUNSPECIFIED
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)UNSPECIFIED
E.I. DuPont de Nemours & Co.UNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
Illinois Department of CommerceIBHE HECA NWU 96
Department of Energy (DOE)W-31-102-Eng-38
Illinois Board of Higher EducationUNSPECIFIED
Issue or Number:16
Record Number:CaltechAUTHORS:20170724-070313798
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Official Citation:Effect of Mesophase Order on the Dynamics of Side Group Liquid Crystalline Polymers Maria L. Auad, Michael D. Kempe, Julia A. Kornfield, Stanley Rendon, Wesley R. Burghardt, and Kyunghwan Yoon Macromolecules 2005 38 (16), 6946-6953 DOI: 10.1021/ma050551f
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79278
Deposited On:24 Jul 2017 16:58
Last Modified:15 Nov 2021 17:46

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