Photoreaction in mesogenic media, 5. Photoinduced optical anisotropy of liquid‐crystalline sidechain polymers with azochromophores by linearly polarized light of low intensity

Dynamic Photoresponsive Functions in Organized Layer Systems Comprised of Azobenzene-containing Polymers

“…Azobenzene polymers are potentially useful as materials for reversible holographic information storage and photonic devices. [94][95][96][97][98] Surface relief grating (SRG, regular topological surface modification) formed via the irradiation with an interference pattern of coherent light has been demonstrated recently [99][100][101] and is perhaps the most attracting target in the current research of Az polymers. A great deal of data has been accumulated rapidly due to its basic phenomenological interest [102][103][104][105][106][107][108] and to attractive technological applications.…”

Comb-Shaped Polymers with Mesogenic Side Groups as Electro- and Photooptical Active Media

“…Depending on the chemical structure of the spacer and the ratio between the mesogenic and the dye-containing units these copolymers could exist in the amorphous or the LC state [108][109][110][111][112].…”

“…Depending on the phase state of the copolymers, the samples for photo optical measurements were prepared in different ways [108][109][110][111][112]. Samples for optical measurements were prepared by placing an isotropic melt of the copolymer into the slit of a sandwich-type electrooptical cell consisting of two planar, transparent In203 electrodes on a glass substrate, separated by Teflon spacers of various thicknesses (from 6 to 100 flkm).…”

“…Figures 2.31 and 2.32 show the polarized IR and UV/VIS spectra and angular dependence of the intergrated areas of the eN-stretching vibration at 2229 cm-I and the vibration of N=N double bonds of azobenzene groups at 380 nm (the n -n* transition of the trans-azobenzene groups) before and after the irradiation of the copolymer XXII (see copolymer 3 in Table 2.2) [111][112] .…”

Anisotropic phase separation of polymer blends induced by polarization-selective photoisomerization

“…In the intermediate range of temperature, the resulting anisotropy will be determined by the competition between the anisotropy built in by irradiation and the relaxation of the asymmetric concentration fluctuations. Finally, it is worth noting that a number of authors have reported that upon irradiation with linearly polarized light, the isomerization of azobenzene, an analog of stilbene, proceeds toward an equilibrium state where all the dipole moments of the cis-isomer become aligned in the direction perpendicular to the exciting polarization [3][4][5]14) . In this work, because all the experiments were performed at temperatures above T g of the blends and, particularly, all the polymer chains in the blend are flexible, the alignment of individual dipole moments of the stilbene moieties by polarized light, as a short-range effect, might not be able to orient the polymer chains.…”