Organic/Inorganic NLO materials based on reactive polyimides and a bulky alkoxysilane dye via sol/Gel process

A series of the organic–inorganic materials based on reactive polyimides and a bulky alkoxysilane dye (ASD) for second‐order nonlinear optics have been developed. Sol‐gel reaction of ASDs is utilized to grow a network in polymer matrices (composite) or to create inter‐polymer network among polyimide chains (hybrid). Moreover, a full interpenetrating polymer network (IPN) was formed through simultaneous free radical polymerization of a methacryloyl group containing polyimide, and sol‐gel process of ASDs. Scanning electron microscopy (SEM) results indicate that the inorganic networks are distributed uniformly throughout the polymer matrices on the molecular scale. The silica particle sizes are well under 1 µm based on AFM study. Second harmonic coefficients, d₃₃ of 4.5 to 48.5 pm/V have been obtained for the optically clear poled/cured polyimide/ASD samples. Excellent temporal stability was obtained for these NLO materials at 100 °C. The dynamic thermal and temporal stabilities of the IPN system were much better than those of composite and hybrid systems. Copyright ­© 2003 John Wiley & Sons, Ltd.