Orientation Of Azobenzene Groups Research Articles

Functionally integrated liquid crystalline photochromic triple block copolymer with locally light‐ and thermal‐controllable sub‐blocks

ABSTRACTPhotoorientation and reorientation processes induced by illumination of the samples with oppositely directed polarized light and by the thermal treatment were studied for the films of triblock copolymer pAzo10‐b‐pPhM80‐b‐pAzo10 consisting of a nematic phenyl benzoate сentral sub‐block (PhM, DP = 80) with two terminal smectic azobenzene sub‐blocks (Azo, DP = 10). For amorphized films of triblock copolymer, illumination with polarized light (λ = 546 nm) is shown to be by orientation of only Azo‐containing groups, but upon following annealing of the film, PhM groups are adjusted to the orientation of Azo fragments. It was found, that the subsequent illumination of the block copolymer sample with oppositely directed polarized light changes the orientation of azobenzene groups, while the orientation of phenyl benzoate groups is remained unchanged. Thus, the cyclic illumination of the triblock copolymer samples by the linear polarized light and subsequent thermal treatment make it possible to control and fix orientation of azobenzene and phenyl benzoate groups located in different sub‐blocks in the desired and independent manner. The comparison of these results with the data on random p(Azo7‐ran‐PhM30) copolymer of the similar composition revealed, that in the random copolymer, both Azo and PhM mesogenic groups are involved in the orientational cooperative process regardless of films process treatment. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1602–1611

Photoinduced Orientation of Azobenzene Groups in Polymer Films. Characterization by UV/Visible Spectroscopy

We study the kinetics of the photoinduced orientational ordering of two methacrylic polymers containing different azobenzene groups with both electron-donor and electron-acceptor substituents under irradiating them at two different wavelengths. For the experimental study of the orientational distribution in polymer films, we use the method based on absorption measurements. It is found that azofragments are oriented by either the photoorientation or photoselection mechanism depending on the wavelength. The components of the order parameter tensor of azobenzene fragments are estimated for the initial state and after different doses of irradiation.