Synthesis of nonlinear optical polymers with large photoconductive sensitivity and transparency

Novel nonlinear optical (NLO) chromophore, 2‐{3‐[2‐(4‐methylsulfonylphenyl)vinyl]carbazol‐9‐yl}ethanol was synthesized and subsequently reacted with methacryloyl chloride to give a photoconducting NLO monomer ( M1 ). 2‐Methylacrylic acid 2‐[3‐(diphenylhydrazonomethyl)carbazol‐9‐yl]ethyl ester ( M2 ) was also synthesized as a comonomer to enhance the carrier mobility of the NLO polymer. Photoconducting NLO polymers, P1 and P2 were obtained by the copolymerization of Ml with methyl methacrylate and M2 , respectively. These polymers were well soluble in organic solvents and showed glass transition at 177 °C and 196 °C, respectively. Polymer films of P1 and P2 were optically clear, and were transparent at wavelengths longer than 420 nm. The electro‐optic coefficient (r 33 ) of poled P1 films was measured to be ∼5 pm/V at 632.8 nm. The photoconductive sensitivities of P1 and P2 were 6.2 × 10 −14 S·cm −1 /mW·cm −2 and 5.6 × 10 −11 S·cm −1 /mW·cm −2 .