Influence of the presence of organic crystals in the optical response of polimeric networks modified with DO3

OROFINO, A.; GALANTE, M. J.; OYANGUREN, P. A.

Los Cocos, Provincia de Córdoba

Simposio; V Argentine-Chilean Polymer Symposium, VIII Argentine Polymer Symposium & IX Chilean Symposium of Polymer Chemistry and Physical-Chemistry; 2009

Polymers with high optical sensitivity, short access and switching times, reversibility, and high storage densities are being developed for use as optical recording media. It was found that polymers containing azobencene groups had these properties (Wu et al., 1998). When a thin film of the azopolymer is exposed to linearly polarized light, optical anisotropy is generated as a result of molecular photoreorientation of the chromophores to give dichroic and birrefringent films, which are applicable to rewritable optical storage media. The photoresponse of the polymer is based on a cis/trans photoisomerization of azobencene groups (Han et al., 2001), and is affected by the mobility of the groups and any supramolecular order of the polymer. One of the most interesting observations on these polymers is that, if a mixture of mesogens is present in the side chains, the nonphotoactive mesogens undergo a reorientation together with the azo mesogens, thus amplifying the effects over the limits given by the azo groups´ concentration. Initially it was proposed that the cooperative orientation was occurring only above the glass transition temperature of the polymer, but there are evidences that the reorientation by “sympathy” of the nonactive mesogens takes place both above and below Tg. (Wu et al., 1998)