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Photoactive Cholesteric Polymeric Material With Dual Photochromism

Published online by Cambridge University Press:  15 March 2011

Alexey Bobrovsky ,
Natalia Boiko  and
Valery Shibaev
Alexey Bobrovsky
Affiliation:
Department of Chemistry, Moscow State University, Lenin Hills, 119899 Moscow, Russia
Natalia Boiko
Affiliation:
Department of Chemistry, Moscow State University, Lenin Hills, 119899 Moscow, Russia
Valery Shibaev
Affiliation:
Department of Chemistry, Moscow State University, Lenin Hills, 119899 Moscow, Russia
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Abstract

New cholesteric polymeric material containing a liquid crystalline (LC) copolymer with side phenylbenzoate nematogenic and photochromic spiropyran groups and 5 mol % chiral photochromic dopant based on cinnamic acid and isosorbide was prepared. It was shown that UV irradiation and subsequent annealing of planarly-oriented mixture films lead to untwisting of the cholesteric helix and cause an irreversible shift of selective light reflection to the long-wavelength region. This process is explained by the E-Z isomerization of chiral photochromic groups of the dopant relative to a C=C bond accompanied by a decrease in their twisting ability. Upon UV irradiation of films at room temperature, a thermally reversible transformation of spiropyran groups into a merocyanine form takes place, which is followed by the appearance of an intense absorption maximum in the visible spectral region. It was shown, that the use of the material prepared in this work provides an opportunity to record two images at a time: one image is due to a change in the helical pitch and another image (above) is due to the photochromism of spiropyran groups. It is pertinent to note that using the approach developed in this work allows one to widely vary the range of materials exhibiting dual photochromism. It was demonstrated that the mixture under examination shows promise as new photosensitive material for optics, optoelectronics, and data recording.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 709: Symposium CC – Advances in Liquid Crystalline Materials and Technologies , 2001 , CC5.6.1
Copyright
Copyright © Materials Research Society 2002

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References

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