Photoalignment Layers for Liquid Crystals from the Di-蟺-methane Rearrangement

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• 作者：Jason R. Cox ; Jeffrey H. Simpson ; Timothy M. Swager
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：January 16, 2013
• 年：2013
• 卷：135
• 期：2
• 页码：640-643
• 全文大小：352K
• 年卷期：v.135,no.2(January 16, 2013)
• ISSN：1520-5126

文摘

Photoalignment of nematic liquid crystals is demonstrated using a di-蟺-methane rearrangement of a designed polymer. The alignment mechanism makes use of the strong coupling of the liquid crystal directors to dibenzobarrelene groups. The large structural changes that accompany photoisomerization effectively passivate segments of the polymer, allowing the remaining dibenzobarrelene groups to dominate the director alignment. Photoisomerization requires triplet sensitization, and the polymer was designed to have a uniaxially fixed rigid structure and rapid triplet energy transfer from the proximate benzophenone units to the dibenzobarrelene groups. The isomerization was observed to be regiospecific, and thin films showed alignment.