Dipole dynamics and macroscopic alignment in molecular and polymeric liquid crystals by broad-band dielectric relaxation spectroscopy

Jovan Mijovic, Jo Wing Sy

Research output: Contribution to journalArticle

Abstract

A liquid crystal monomer (LCM) was synthesized and attached as a side chain to a siloxane polymer (SCLCP). The molecular dynamics of LCM and SCLCP were investigated by broad-band dielectric relaxation spectroscopy (DRS) over 10 decades of frequency. The surface treatment of the electrodes was found to have a pronounced effect on the macroscopic alignment and dynamics. In the isotropic state the relaxations in LCM and SCLCP are well-described by the Kohlrausch-Williams-Watts (KWW) functional form. In the LC state, the overall dielectric response is a weighted sum of two dispersions that depend on the macroscopic alignment. The hometropic (H) alignment is dominated by the (slower) δ process, while the planar (P) alignment is dominated by the (faster) αm process. Both processes are symmetric and can be described by Cole-Cole (CC) or Fuoss-Kirkwood (FK) functional forms. The δ process governs the dynamics in the SCLCP near the glass transition, similar to the segmental α process in non-LC glass formers. Excellent agreement was observed with the various aspects of the seminal work by Attard and Williams.

Original languageEnglish (US)
Pages (from-to)9620-9629
Number of pages10
JournalMacromolecules
Volume33
Issue number26
DOIs
StatePublished - Dec 26 2000

Fingerprint

Liquid Crystals
Dielectric relaxation
Liquid crystals
Spectroscopy
Monomers
Siloxanes
Dispersions
Surface treatment
Molecular dynamics
Glass transition
Polymers
Glass
Electrodes

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Dipole dynamics and macroscopic alignment in molecular and polymeric liquid crystals by broad-band dielectric relaxation spectroscopy. / Mijovic, Jovan; Sy, Jo Wing.

In: Macromolecules, Vol. 33, No. 26, 26.12.2000, p. 9620-9629.

Research output: Contribution to journalArticle

@article{6feb4f81716245d8a111b5e0e2154d89,
title = "Dipole dynamics and macroscopic alignment in molecular and polymeric liquid crystals by broad-band dielectric relaxation spectroscopy",
abstract = "A liquid crystal monomer (LCM) was synthesized and attached as a side chain to a siloxane polymer (SCLCP). The molecular dynamics of LCM and SCLCP were investigated by broad-band dielectric relaxation spectroscopy (DRS) over 10 decades of frequency. The surface treatment of the electrodes was found to have a pronounced effect on the macroscopic alignment and dynamics. In the isotropic state the relaxations in LCM and SCLCP are well-described by the Kohlrausch-Williams-Watts (KWW) functional form. In the LC state, the overall dielectric response is a weighted sum of two dispersions that depend on the macroscopic alignment. The hometropic (H) alignment is dominated by the (slower) δ process, while the planar (P) alignment is dominated by the (faster) αm process. Both processes are symmetric and can be described by Cole-Cole (CC) or Fuoss-Kirkwood (FK) functional forms. The δ process governs the dynamics in the SCLCP near the glass transition, similar to the segmental α process in non-LC glass formers. Excellent agreement was observed with the various aspects of the seminal work by Attard and Williams.",
author = "Jovan Mijovic and Sy, {Jo Wing}",
year = "2000",
month = "12",
day = "26",
doi = "10.1021/ma0014158",
language = "English (US)",
volume = "33",
pages = "9620--9629",
journal = "Macromolecules",
issn = "0024-9297",
publisher = "American Chemical Society",
number = "26",

}

TY - JOUR

T1 - Dipole dynamics and macroscopic alignment in molecular and polymeric liquid crystals by broad-band dielectric relaxation spectroscopy

AU - Mijovic, Jovan

AU - Sy, Jo Wing

PY - 2000/12/26

Y1 - 2000/12/26

N2 - A liquid crystal monomer (LCM) was synthesized and attached as a side chain to a siloxane polymer (SCLCP). The molecular dynamics of LCM and SCLCP were investigated by broad-band dielectric relaxation spectroscopy (DRS) over 10 decades of frequency. The surface treatment of the electrodes was found to have a pronounced effect on the macroscopic alignment and dynamics. In the isotropic state the relaxations in LCM and SCLCP are well-described by the Kohlrausch-Williams-Watts (KWW) functional form. In the LC state, the overall dielectric response is a weighted sum of two dispersions that depend on the macroscopic alignment. The hometropic (H) alignment is dominated by the (slower) δ process, while the planar (P) alignment is dominated by the (faster) αm process. Both processes are symmetric and can be described by Cole-Cole (CC) or Fuoss-Kirkwood (FK) functional forms. The δ process governs the dynamics in the SCLCP near the glass transition, similar to the segmental α process in non-LC glass formers. Excellent agreement was observed with the various aspects of the seminal work by Attard and Williams.

AB - A liquid crystal monomer (LCM) was synthesized and attached as a side chain to a siloxane polymer (SCLCP). The molecular dynamics of LCM and SCLCP were investigated by broad-band dielectric relaxation spectroscopy (DRS) over 10 decades of frequency. The surface treatment of the electrodes was found to have a pronounced effect on the macroscopic alignment and dynamics. In the isotropic state the relaxations in LCM and SCLCP are well-described by the Kohlrausch-Williams-Watts (KWW) functional form. In the LC state, the overall dielectric response is a weighted sum of two dispersions that depend on the macroscopic alignment. The hometropic (H) alignment is dominated by the (slower) δ process, while the planar (P) alignment is dominated by the (faster) αm process. Both processes are symmetric and can be described by Cole-Cole (CC) or Fuoss-Kirkwood (FK) functional forms. The δ process governs the dynamics in the SCLCP near the glass transition, similar to the segmental α process in non-LC glass formers. Excellent agreement was observed with the various aspects of the seminal work by Attard and Williams.

UR - http://www.scopus.com/inward/record.url?scp=0034499915&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034499915&partnerID=8YFLogxK

U2 - 10.1021/ma0014158

DO - 10.1021/ma0014158

M3 - Article

VL - 33

SP - 9620

EP - 9629

JO - Macromolecules

JF - Macromolecules

SN - 0024-9297

IS - 26

ER -