Rheological properties and conformation of a side-chain liquid crystal polysiloxane dissolved in a nematic solvent

Yiqiang Zhao, Shaosheng Dong, Alex M. Jamieson, Xuesong Hu, Jyotsana Lal, Sergei Nazarenko, Stuart J. Rowan

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We report measurements of the change in electrorheological response of the low molar mass nematic pentylcyanobiphenyl (5CB) on dissolution of small amounts of a side-chain liquid crystal polymer (SCLCP). From the ratio of the intrinsic viscosities with the field on and off, [η on] and [η off], respectively, we deduce a value for the ratio of the rms end-to-end distances of the SCLCP parallel and perpendicular to the nematic director, R par;/R = 1.17 ± 0.02 via application of the Brochard hydrodynamic model, which indicates that the polymer has a slightly prolate shape. Small-angle neutron scattering measurements reveal a numerically similar value for the corresponding ratio of apparent rms radii of gyration, R g∥R g⊥ = 1.12 ± 0.06, for the SCLCP dissolved in deuterated 5CB. Observations of the shear stress transient response of a homeotropic monodomain indicate that, at a concentration between 0.01 and 0.02 g/mL, the solution exhibits a transition from director-aligning to director-tumbling behavior. This result is inconsistent with the Brochard model, which predicts such a transition only for a polymer with an oblate shape but agrees with a modified version, which assumes an additional contribution to viscous stress arises due to elastic coupling between the solvent and polymer directors.

Original languageEnglish
Pages (from-to)5205-5213
Number of pages9
JournalMacromolecules
Volume38
Issue number12
DOIs
Publication statusPublished - 2005 Jun 14
Externally publishedYes

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Siloxanes
Liquid Crystals
Liquid crystal polymers
Silicones
Liquid crystals
Conformations
Polymers
Phosmet
Barreling
Molar mass
Neutron scattering
Transient analysis
Shear stress
Dissolution
Hydrodynamics
Viscosity
liquid crystal polymer

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Zhao, Y., Dong, S., Jamieson, A. M., Hu, X., Lal, J., Nazarenko, S., & Rowan, S. J. (2005). Rheological properties and conformation of a side-chain liquid crystal polysiloxane dissolved in a nematic solvent. Macromolecules, 38(12), 5205-5213. https://doi.org/10.1021/ma050485h

Rheological properties and conformation of a side-chain liquid crystal polysiloxane dissolved in a nematic solvent. / Zhao, Yiqiang; Dong, Shaosheng; Jamieson, Alex M.; Hu, Xuesong; Lal, Jyotsana; Nazarenko, Sergei; Rowan, Stuart J.

In: Macromolecules, Vol. 38, No. 12, 14.06.2005, p. 5205-5213.

Research output: Contribution to journalArticle

Zhao, Y, Dong, S, Jamieson, AM, Hu, X, Lal, J, Nazarenko, S & Rowan, SJ 2005, 'Rheological properties and conformation of a side-chain liquid crystal polysiloxane dissolved in a nematic solvent', Macromolecules, vol. 38, no. 12, pp. 5205-5213. https://doi.org/10.1021/ma050485h
Zhao, Yiqiang ; Dong, Shaosheng ; Jamieson, Alex M. ; Hu, Xuesong ; Lal, Jyotsana ; Nazarenko, Sergei ; Rowan, Stuart J. / Rheological properties and conformation of a side-chain liquid crystal polysiloxane dissolved in a nematic solvent. In: Macromolecules. 2005 ; Vol. 38, No. 12. pp. 5205-5213.
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