Optical anisotropy photoinduced

Blinov, L. M., Kozlovsky, M. V., Ozaki, M., Skarp, K., and Yoshino, K. Photoinduced diefaroism and optical anisotropy in a liquid crystalline azobenzene side-chain polymer caused by anisotropic angular distribution of trans and cis isomers./. Appl. Phys. 84, 3860 (1998). 

Liquid-crystalline phases with two-dimensional order (Table 1) influence photochromic processes because their molecular orientation is reversibly altered by photochromic reactions owing to the marked structural changes of the photoactive molecules.3 Intensive interest has been focused on the photoinduced alteration of mesophases admixed with photochromic compounds, since photochromism can be transformed to the reversible modification of the optical anisotropy of liquid-crystalline states. This phenomenon is applicable to optical storage of information as nondestructive readout can be performed with light of wavelengths far from those causing the photochromic reactions. 

H. Akiyama, K. Kudo, and K. Ichimura, Command surfaces. 10. Novel polymethacrylates with laterally attached azobenzene groups displaying photoinduced optical anisotropy, Makromol... 

T. Fischer, L. Lasker, J. Stumpe, and S. G. Kostromin, Photoinduced optical anisotropy in films of photochromic liquid crystalline polymers, Photochem. Photobiol. A 80, 453 159... 

L. Lasker, T. Fischer, J. Stumpe, S. Kostromin, S. Ivanov, V. Shivaev, and R. Ruhmann, Photoinduced optical anisotropy in thin films of amorphous photochromic side chain polymers. Mol. Cryst. Liq. Cryst. 246, 347-350 (1994). 

Barnik M I, Kozenkov V M, Shtykov N N, Palto S P and Yudin S G 1989 Photoinduced optical anisotropy in Langmuir-Blodgett films J. Mol. Electron. 5 53-6... 

Stumpe J, et al. 1991. Photoreaction in mesogenic media. 5. Photoinduced optical anisotropy of liquid crystalline side chain pol5uners with azochromophores by linearly polarized light of low intensity. Makromol Chem, Rapid Commun 12(2) 81 87. 

The development of H-bonded complexes is now considered. An influence of UV irradiation on optical properties of low-molecular-weight azobenzene-con-taining material (Fig. 2.4b) has been investigated (Aoki et ah, 2000) on the basis of such interactions. The first observation of photoinduced optical anisotropy in H-bonded complexes of azobenzene dyes and copolymers (Fig. 2.4b) has been recently demonstrated (Medvedev et ah, 2005). In this case, the induced anisotropy was stable, and the maximum dichroic ratio of 2 has been observed. A kinetics of the induction of birefringence (maximum value of ca. 0.01) in one of these complexes is shown in Fig. 2.5. An influence of H-bonding on the mesomorphic and photoorientation properties was recently demonstrated (Cui and Zhao, 2004). In this approach, the amorphous azopyridine side-chain polymer was converted into liquid crystalline polymers through self-assembly with a series of commercially available, aliphatic, and aromatic carboxylic acids (Fig. 2.4d). 

Stumpe J, Muller L, Kreysig D, Hauck G., Koswig HD, Ruhmann R, Rubner J. 1991. Photoinduced optical anisotropy of liquid crystalline side chain polymer with azochro mophores by low intensity of linearly polarized light. Makromol Chem Rapid Commun... 

A vast amount of investigations on photoalignment of LCs has been reported during the past one and a half decades. Irradiation with LPL induces photo-induced anisotropy, in which molecules are generally oriented to an unexcitable direction, namely, perpendicular to the electric vector of the polarization direction. This effect is called photoinduced optical anisotropy (Seki, 2004 Natansohn and Rochon, 2002 Ichimura, 2000). 

E. Schab-Balcerzak, B. Sapich, and J. Stumpe. Photoinduced optical anisotropy in new poly(amide imide)s with azobenzene units. Polymer, 46(1) 49-59, January 2005. 

Berges, C., Gimeno, N., Oriol, L., Pinol, M., Forcdn, E, Sanchez, C. and Alcala, R. (2012a) Photoinduced optical anisotropy in azobenzene containing block copolymer-homopolymer blends. Influence of mrcrostructure and molecular weight , Eur. Polym. J., 48, 613. 

Hernandez-Ainsa, S., Alcala, R., Barbera, J., Marcos, M., Sanchez, C. and Serrano, J.L. (2011) Ionic azo-codendrimers Influence of the acids contents in the hq-uid crystalhne properties and the photoinduced optical anisotropy , liMr. Polym. L, 37,311-318. 

Kidowaki, M., Fujiwara,T.,Morino, S.Y., Ichimura, K. and Stumpe, J. (2000) Thermal amplification of photoinduced optical anisotropy of p-cyanoazobenzene polymer films monitored by temperature scanning ellipsometry ,/. Appl. Phys. Lett., 76,1377 (3 pages). 

S. Hernandez-Ainsa, R. Alcala, J. Barbera, M. Marcos, C. Sanchez, J.L. Serrano, Ionic azo-codendrimers influence of the acids contents in the liquid crystalline properties and the photoinduced optical anisotropy. Europ. Poly. J. 47, 311-318 (2011)... 

Figure 2.16 Order parameter in the photochemical reaction of photodegradation as a function of UV exposure time (upper, [70]) and UV exposure dosage (lower, [20]). Reproduced from M. Hasegawa, Modeling of photoinduced optical anisotropy and anchoring energy of polyimide exposed to linearly polarized deep UV light. Japanese Journal of Applied Physics 38, L457 (1999), Institute of Pure and Applied Physics...

S. P. Palto, N. M. Shtykov, V. A. Khavrichev, and S. G. Yudin, Photoinduced optical anisotropy in Langmuir-Blodgett films. Molecular Materials 1, 3 (1992). 

M. Hasegawa, Modeling of photoinduced optical anisotropy and anchoring energy of polyimide exposed to linearly polarized deep UV light. Japanese Journal of Applied Physics 38, L457 (1999). 

S. Palto, J. Malthete, C. Germain, and G. Durand, On the nature of photoinduced optical anisotropy in diacetylene Langmuir-Blodgett films. Molecular Crystals and Liquid Crystals 282, 451 (1996). 

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