Azobenzene polymers

Yamaguchi, I. Osakada, K. and Yamamoto, T. (2000) Pseudopolyrotaxane composed of an azobenzene polymer and y-cyclodextrin. Reversible and irreversible photoisomerization of the azobenzene groups in the polymer chain, Chem. Commun. 1335-1336. 

Monolayers representing two-dimensional arrays of membrane-mimetic assemblies, consisting of azobenzene (poly-L-lysine) with 43 % loading of the photoisomerizable units, were prepared.1441 The compressed trans-azobenzene polymer mono-layer exhibited a surface pressure of 7 mN m 1, whereas photoisomerization of the monolayer to the cis-azobenzene state by UV light decreased the surface pressure to... 

Fukuda T, Matsuda H, Shiraga T et al. (2000) Photofabrication of surface relief grating on films of azobenzene polymer with different dye functionalization. Macromolecules 33 4220-4225... 

Saphiannikova M, Geue T M, Hennenberg O, Morawetz K, Pietsch U. (2004) Linear viscoelastic analysis of formation and relaxation of azobenzene polymer gratings. J Chem Phys 120 4039 045... 

Eisenbach C. D., Dimberger, K., and Ficht, K. (1998). Matrix relaxation and local free volume effects in mono- and bichromophoric azobenzene polymers. Polym. Prepr. 39, 279-280. 

Gu, J., Liang, B., Liu, L., Xian, Y., Chen, Y., Lu, B., and Lu, Z. Photoinduced properties of liquid crystalline azobenzene polymer in Langmuir-Blodgett films investigated bv surface plasmon resonance. Thin Solid Films 327—329, 427 (1998). 

Azobenzene chromophores have been incorporated not only in side chain polymers, but also in other polymer structures. There are several examples of incorporation of azobenzene into the polymer backbone or in the backbone and in the side chain. In these works, the main interest was to realize photoinduced changes of the polymer coil in solution. Some of the main-chain azobenzene polymers were investigated in monolayers at the... 

The role of the supramolecular order of LBK films on the photoreorientation of azobenzene moieties upon polarized irradiation was investigated in detail. It was found that the photo(re)orientation proceeds reaclily in disordered, spin-coated films of azobenzene polymer 34 or azobenzene-containing polypeptide 38, whereas the photoreorientation is hindered in highly ordered LBK films of these polymers. In the case of polyacrylaerylat 34 and polypeptides 38 with shorter spacers (n = 2), the photoreorientation proceeds readily after the structure of the LBK film has been randomized by UV irradi-... 

Pietsch, U., Rochon, P., Natansohn, A. (2000). Formation of a buried lateral density grating in azobenzene polymer films. Adv. Mater. 12, 1129-1132. 

FIG. 14.4 A typical sinusoidal-shaped SRG inscribed on a side-diain azobenzene polymer. 

Pedersen, T. G., Johansen, P. M., Holme, N. C. R., and Ramanujam, P. S. Mean-field theory of photoinduced formulation of surface reliefs in side-chain azobenzene polymers. Phys. Rev. Lett. 199S, m, 89-91. 

Fukuda, X., Sumaru, K., Yamanaka, X, and Matsuda, H. Photo-induced formation of the surface relief grating on azobenzene polymers Analysis based on the fluid mechanics. Mol. Cryst. and Liq. Cryst. 2000, 345, pp. 263-268. 

Leopold, A., Wolff, J., Baldus, O., Huber, M. R., Bieringer, X, and Zilker, S. J. Xhermally induced surface relief gratings in azobenzene polymers. J. Chem. Phys. 2000, 113, pp. 833-837. 

Fukuda, X, Matsuda, H., Viswanathan, N. K., Xripathy, S. K., Kumar, J., Shiraga, X., Kato, M., and Nakanishi, H. Systematic study on photofabrication of surface relief grating on high-Xg azobenzene polymers. Synethetic Met. 1999, 102, pp. 1435-1436. 

Jiang, X. L., Li, L., Kumai J., Kim, D. Y., and Xripathy, S. K. Unusual polarization dependent optical erasure of surface relief gratings on azobenzene polymer films. Appl. Phys. Lett. 1998, 72, pp. 2502-2504. 

Stockermans, R. J., and Rochon, P. L. Narrow-band resonant grating waveguide filters con-strueted with azobenzene polymers. Appl. Opt. 1999, 38, pp. 3714-3719. 

In contrast to the first-order kinetics of the conventional azobenzene isomerization in solution, a slight deviation from first-order kinetics was observed even in aqueous solutions for polyelectrolytic azobenzene polymers substituted with hydrophobic alkyl residues (14, Fig. 4).43 In an aqueous solution of the amphiphilic polysulfonates containing a small amount of azobenzene moiety, the extent of E-to-Z photoisomerization under UV irradiation was reduced as a result of the compartmentalization of the azo chromophores in a hydrophobic core, which resulted in motion of their restriction. 

The photoselection in azobenzene polymers (Figure 11) is rather a general phenomenon.77-84 Systematic studies have been conducted by Natansohn and coworkers on the photoinduced molecular reorientation of azobenzene units to induce birefringence and dichroism of thin films of acrylate amorphous polymers with Dispose Red (DR) pendant residues, which have been attracting extensive... 

Y. Kawanishi, T. Tamaki, and K. Ichimura, Photochemical control of nematic liquid crystalline orientation by the anisotropic photochromism of surface azobenzenes, Polym. Mater. Sci. Eng. 66, 263-264 (1992). 

Y. Kawanishi, T. Tamaki, T. Seki, M. Sakuragi, Y. Suzuki, and K. Ichimura, Multifarious liquid crystalline textures formed on a photochromic azobenzene polymer film, Langmuir 7,1314-1315 (1991). 

Liquid crystalline azobenzene polymers can undergo photoisomerization on irradiation at 360 or 450 nm on gold films. This permits changing the refractive index of the film depending upon the wavelength used136. A study has examined the photopolymerization of p-styrene sulphonate counteranions associated with monolayers of disulphide amphiphiles as self-assembled monolayers on gold137. 

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