ORIGINAL PAPER Chirooptical and photooptical properties of a novel side-chain azobenzene-containing LC polymer Alexey Bobrovsky Æ Valery Shibaev Æ Vera Hamplova Æ Miroslav Kaspar Æ Milada Glogarova Received: 16 November 2008 / Accepted: 24 November 2008 / Published online: 20 February 2009 Ó Springer-Verlag 2009 Abstract A novel chiral–photochromic side-chain poly- acrylate with azobenzene fragments in the side groups has been synthesised. It was shown that the polymer forms a smectic phase and a cholesteric supramolecular helical structure with selective light reflection in IR spectral range. Thin spin-coated films of the polymer were prepared and their photooptical and chirooptical properties were studied in detail. It was found that UV irradiation of the films led to E–Z isomerization of the azobenzene moieties with high conversion, which is dependent on thermal prehistory of the films. Subsequent action of visible light results in partial recovery of the E-isomer content, whereas annealing leads to the full back conversion. Circular dichroism (CD) measurements revealed formation of the helical supramo- lecular structure even in the initial spin-coated polymer films. The E–Z isomerization induces complete disruption of helical order in non-annealed films of the polymer, whereas in the smectic phase of the annealed film only a significant decrease in CD values was found. In addition, the photoorientation phenomena induced by polarized light were studied. It was shown that polarized light induces linear dichroism in the films provided by azobenzene group orientation and the dichroism is stable at room temperature for a prolonged time. These combined chirooptical and photooptical features of this novel polymer enable one to consider this multifunctional compound as a promising material for photonics and for optical applications. Keywords Liquid crystals  Photochemistry  Spectroscopy  Chirality Introduction Azobenzene-containing polymers are an interesting and promising class of macromolecular compounds which can be used for a variety of applications—in optics, optoelec- tronics, photonics, holography, data storage, etc. [1–3]. The reasons for such interest in azobenzene derivatives are quite clear. On irradiation with light azobenzene moieties of such polymers undergo reversible E–Z isomerization with high quantum yield and the polymers have rather high fatigue resistance [1, 2]. N N R' R N R N R' E-isomer Z-isomer λ 1 λ 2 , Τ It should be emphasized that isomerization of the azo- benzene derivatives is accompanied by a large change in the anisometry and dipole moment. Both effects affect the phase behaviour and optical properties of low-molar-mass and polymer systems [3]. Nowadays the attention of many research groups working with azobenzene-containing polymers is focused on several topics including study of surface relief grating formation [4–8], holography [9–11], and chirality induction by means of the action of circularly or elliptically polarized light [12–14]. The most interesting outcome of the above A. Bobrovsky (&)  V. Shibaev Faculty of Chemistry, Moscow State University, Leninskie gory, 119992 Moscow, Russia e-mail: bbrvsky@yahoo.com V. Hamplova  M. Kaspar  M. Glogarova Institute of Physics, Academy of Sciences of the Czech Republic, 182 21 Prague 8, Czech Republic 123 Monatsh Chem (2009) 140:789–799 DOI 10.1007/s00706-009-0108-8