Photoreactive groups reactions

Of the following amine-reactive and photoreactive cross-linkers, the overwhelming majority use an aryl azide group as the photosensitive function. Only a few use alternative photoreactive chemical reactions, particularly perfluorinated aryl azide, benzophenone, or diazo compounds. For general background information on photoreactive cross-linkers see Das and Fox (1979), Kiehm and Ji (1977), Vanin and Ji (1981), Meijer et al., 1988), and Brunner (1993). 

Most polymers are not miscible. Introducing chemical reactions to an initially miscible polymer mixture often leads to phase separation (50). Autocatalytic behavior driven by tchemical reactions and concentration fluctuations in miscible polymer mixtures was recently found in photo-cross-linked polymer mixtures 31). Concentration fluctuations increase as the reaction proceeds, leading to the condensation of photoreactive groups labeled on one of the polymer components. This condensation leads to an increase in the reaction yield that, in turn, accelerates the concentration fluctuations.. A positive feedback can thus be built in the reacting mixture under appropriate conditions. 

Corona poling technique in the wire to plane geometry as well as parallel electrode poling techniques have been used to pole these classes of polymers in film form. Poling is carried out prior to crosslinking to align the NLO units and possibly poise the photoreactive groups for photo-induced solid state reaction. 

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