Preparation of a copolymer for second order nonlinear optics

During the last decade the interest in polymeric materials for second-order nonlinear optical properties has been constantly growing. They combine structural electronic properties, with good thermal and mechanical stability, a relatively low cost and easy processability. The second order nonlinear optical (NLO) properties of such materials have electronic origin, with an ultra-fast response time. In the present paper, we report the preparation and characterisation of a new material with a higher concentration of a NLO chromophore. We have synthesised a new dye monomer by the phase transfer catalysed reaction. We have prepared the copolymer with styrene, by bulk copolymerization; the initiator was di-t-butyl peroxide at 120 degrees C. We have characterised the monomer and the copolymer by IR; UV-Vis; H-1-NMR spectroscopy. The glass transition temperature (T-G) and the melting point have been obtained using the differential scanning calorimetry. For studying the NLO properties, the samples have been poled by the Corona poling method, in an electric field of approx. 100V/mu m. We have appreciated the second-order nonlinear coefficient by comparing the light signal passing through the sample, with the signal passing through a standard quartz plate.