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Updated: May 15, 2026

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
Photoalignment layers for liquid crystals from the di-π-methane rearrangement
Jason R Cox1, Jeffrey H Simpson, Timothy M Swager
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Abstract:
Photoalignment of nematic liquid crystals is demonstrated using a di-π-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.
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