Photorefractive polymer chromophore properties

E. Hendrickx, Y. D. Zhang, K. B. Ferrio, J. A. Herlocker, J. Anderson, N. R. Armstrong, E. A. Mash, A. P. Persoons, N. Peyghambarian, and B. Kip-pelen. Photoconductive properties of PVK-based photorefractive polymer composites doped with fluorinated styrene chromophores. J. Mater. Chem., 9(9) 2251-2258, September 1999. 

Hendrickx E, Zhang YD, Ferrio KB, Herlocker JA, Anderson J, Armstrong NR, et al. Photo-conductive properties of PVK-based photorefractive polymer composites doped with fluo-rinated styrene chromophores. J Mater Chem 1999 9(9) 2251-8. 

Because of the versatility of the polyurethane system it is possible to introduce comonomers which can affect the physical properties of the derived polymers. For example, photo cross-linkable polyurethanes are formulated using 2,5-dimethoxy-2,4 -diisocyanato stilbene as a monomer (76). Comonomers, having an azoaromatic chromophore, are used in optical bleaching applications (77), or in the formation of photorefractive polymers (78). The latter random poljnners have second-order nonlinear optical (NLO) properties. Linear poljnners are also obtained from HDI/PTMG and diacetylenic diols. These polymers can be cross-linked through the acetylenic linkages producing a network polymer with properties similar to poly(diacetylenes) (79). 

This polymer contains an electro-optic chromophore (labeled as EO), a chargetransporting group (labeled as CT) and an alkyl group to control the Tg of the polymer (labeled as CTG). The relative ratio of these groups can be varied to optimize the photorefractive property (5). 

Also, polymers that contain carbazole moieties in the backbone with two acceptor groups as multifunctional chromophores were synthesized. The sytheses were carried out by a Knoevenagel polycondensation of divinylcarbazoles with bis(cyanoacetate)s using 4-(N,N -dimethyl)pyridine as a base. Second-order nonlinear optical properties of the polymers were confirmed by second harmonic generation. The photorefractive optical gain of these polymers was demonstrated to be high. 

On the other hand, formation of photorefi active silicone composite with good performance was reported A carbazole-substituted polysiloxane that was sensitized by 2,4,7-trinitro-9-fluorenone was used as a photoconducting medium and l-[4-(2-nilrovinyl)phenylpiperidine was added as an optically nonlinear chromophore. The photorefractive property of polymer was determined by diffraction efficiency using a 100 pm-thick film. The maximum diffraction efficiency (rj max) of 71% was obtained at the electric field of 70 V/pm. 

Dissymmetric systems shows exciton splitting of dichroic absorptions and optical activity and photochromic materials having NLO, photoresponsiveness and photorefractivity properties, which occurred due to the presence of azoaromatic and chiral functionalities in the polymers [62]. Finally, novel optically active multifunctional methacrylic copolymers were synthesized, which contained side-chains chiral moieties and linked to a photoconductive carbazolic and to a photochromic azoaromatic chromophores... 

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