Synthesis of photoconducting nonlinear optical side-chain polymers containing carbazole derivatives

Two kinds of multifunctional monomers, 2-methyl-acrylic acid 6-[3-[2-cyano-2-(4-nitrophenyl)-vinyl]-carbazol-9-yl]hexyl ester (M1) and 2-methyl-acrylic acid 6-[3-[2-(4-nitrophenyl)-vinyl]-carbazol-9-yl]hexyl ester (M2) were synthesized to possess both photoconductivity and nonlinear optical (NLO) properties. Photoconducting NLO polymers (P1, P2) were obtained by the copolymerization of these multifunctional monomers with methylmethacrylate. Charge-transporting monomer, 2-methyl-acrylic acid 6-[3-(diphenyl-hydrazonomethyl)-carbazol-9-yl]hexyl ester (M3) was also synthesized and copolymerized with M1 or M2 to give the photoconducting NLO polymers (P3, P4) with enhanced photoconductivity. The successful polymerization was identified by spectroscopic means and gel permeation chromatography analysis. These polymers were very soluble in common solvents and high optical quality films could be easily fabricated by spin coating. Second harmonic generation (SHG) measurement confirmed P1 and P2 possessed high NLO activity. From the preliminary measurement of photoconductivity, it was found that P1 possessed distinct photoconductivity. It was also found that P3 and P4 showed much higher photoconductivity than Fl, presumably due to the enhanced charge transporting property of M3 structure. (C) 1999 Elsevier Science B.V. All rights reserved.