Photoinduced Anisotropy and LC Photoalignment Properties of Polyvinylcinnamate Films
作者:
Beate Sapich,
Joachim Stumpe,
Igor Gerus,
Oleg Yaroshchuk,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 2000)
卷期:
Volume 352,
issue 1
页码: 9-18
ISSN:1058-725X
年代: 2000
DOI:10.1080/10587250008023156
出版商: Taylor & Francis Group
关键词: photoinduced anisotropy;polyvinylcinnamate;LC photoalignment
数据来源: Taylor
摘要:
The induction of optical anisotropy caused by linearly polarized light was studied in spin-coated films of poly(vinyl 4-fluorocinnamate), PVCN-F. The photoinduced anisotropy was characterized by UV/Vis and IR dichroism, birefringence measurements and the alignment of liquid crystals. The generated anisotropy is discussed with respect to (2+2) photocy-cloadditions and E/Z photoisomerisation. It is shown that both reactions cause anisotropy in the films on irradiation with linearly polarized light. The kinetics of the induction of dichroism and birefringence are different caused by the contributions of both mechanism. The photoproducts of the photocross-linking does not show a significant dichroism. This is dominated by the photoorientation of the cinnamic ester side groups even in the photocross-linked film. This mechanism also causes the repeated reorientation of the optical axis by changing the direction of light polarization in the film plane. Both mechanisms lead to LC alignment caused by the anisotropic interfaces of the films.
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