ICCAS OpenIR
Electrostatic-field-induced chain alignment of liquid crystalline copolyether TPP thin films
Xie, FC; Hu, ZJ; Liu, JP; Yang, XN; Yan, DH; He, TB; Zheng, RQ; Cheng, SZD; Percec, V
2001-04-01
Source PublicationPOLYMER
ISSN0032-3861
Volume42Issue:9Pages:4039-4044
AbstractA liquid crystalline (LC) copolyether has been synthesized from 1-(4-hydroxy-4'-biphenyl)-2-(4-hydroxyphenyl)propane with 1,7-dibromoheptane and 1,11-dibromoundecane with a 50/50 (both in %) equal composition of the 7- and 11-methylene monomers [coTPP-7/11(5/5)]. A mono-domain with a homeotropic alignment can be induced by a thin film surface in the LC phase. When an electrostatic field is applied to the surface-induced mono-domains parallel to the thin film surface normal, the molecular alignment undergoes a change from the homeotropic to uniaxial homogeneous arrangement. However, when the field is applied to a direction perpendicular to the thin film surface normal. the molecular alignment is about 10 degrees -tilt with respect to the homeotropic alignment toward the a*-axis. This is because the permanent dipole moment of the copolyether is not right vertical to the molecular direction. The calculation of molecular dipoles indicates that the permanent dipole moment of this copolyether is about 70 degrees away from the molecular axis, which leads to a negative dielectric anisotropy. It is speculated that the 10 degrees- rather than 20 degrees -tilt is due to a balance between the alignment induced by the electrostatic field and the surface. In the electrostatic field, molecules are subjected to a torque tau, which is determined by the permanent dipole moment P and the electrostatic field E: tau = P x E. The molecular realignment in both parallel and perpendicular directions to the thin film surface normal is determined by satisfying the condition of tau = P x E = 0. (C) 2001 Elsevier Science Ltd. All rights reserved.
KeywordLiquid Crystal Alignment Electric Field
Indexed BySCI
Language英语
WOS IDWOS:000167050400011
PublisherELSEVIER SCI LTD
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Document Type期刊论文
Identifierhttp://ir.iccas.ac.cn/handle/121111/76800
Collection中国科学院化学研究所
Corresponding AuthorHe, TB
Affiliation1.Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Jilin, Peoples R China
2.Univ Akron, Maurice Morton Inst, Akron, OH 44325 USA
3.Univ Akron, Dept Polymer Sci, Akron, OH 44325 USA
4.Univ Penn, Dept Chem, Philadelphia, PA 19104 USA
Recommended Citation
GB/T 7714
Xie, FC,Hu, ZJ,Liu, JP,et al. Electrostatic-field-induced chain alignment of liquid crystalline copolyether TPP thin films[J]. POLYMER,2001,42(9):4039-4044.
APA Xie, FC.,Hu, ZJ.,Liu, JP.,Yang, XN.,Yan, DH.,...&Percec, V.(2001).Electrostatic-field-induced chain alignment of liquid crystalline copolyether TPP thin films.POLYMER,42(9),4039-4044.
MLA Xie, FC,et al."Electrostatic-field-induced chain alignment of liquid crystalline copolyether TPP thin films".POLYMER 42.9(2001):4039-4044.
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