Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (09): 1056-1060.doi: 10.3866/PKU.WHXB20060904

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Alignment Behavior of Liquid Crystals on the Crosslinked Film of Monomers with Fluorinated Groups

FEI Chun-Hong;ZHANG Ling-Li;YAO Li-Shuang;LV Feng-Zhen;AO Zhi-Min;PENG Zeng-Hui;XUAN Li   

  1. (State Key Laboratory of Applied Optics, Fine Mechanics and Physics, Changchun Institute of Optics, Chinese Academy of Sciences, Changchun 130033, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, P. R. China; College of Material Science and Engineering, Jilin University, Changchun 130022, P. R. China)
  • Received:2006-01-16 Revised:2006-03-28 Published:2006-09-04
  • Contact: XUAN Li

Abstract: A series of photosensitive monomers, including hexafluorobiphenol A dicinnamate ester (6F-BADE) and fluorinated dicinnamate esters (FDE-n, n=2, 3, 4), were synthesized. These monomers could be crosslinked under irradiation of linearly polarized ultraviolet light. FTIR spectra and GPC spectra were used to measure the results in real time. The results indicated that the crosslinking reaction was [2+2] cycloaddition. The photoalignment films formed by monomers under the ultraviolet light could induce different types of liquid crystal (LC) alignments: 6F-BADE and FDE-n films resulted in vertical and parallel alignments, respectively. AFM images of the surfaces of the alignment showed no obvious anisotropy on the surfaces of these films. Finally, it was found that, using semiempirical method AM1 of quantum mechanics, the difference of the polarities among different monomer molecules was large, which was considered to be the main cause resulting in different LC alignments.

Key words: Liquid crystal, Photosensitive monomers, [2+2] cycloaddition, Photoalignment, Fluorine, Semiempirical method