NOVEL TYPES OF POLYESTERS CONTAINING 2ND-ORDER NONLINEAR OPTICALLY-ACTIVE CHROMOPHORES WITH HIGH-DENSITY

This article describes the syntheses and second-order nonlinear optica l (NLO) properties of novel types of polyesters containing second-orde r NLO active chromophores with high density, which were obtained by co ndensation polymerization using two comonomers with the N,N-dialkyl-4- nitroaniline or N,N-dialkyl-4-((4-cyanophenyl)azo)anilin moiety. The p olyesters were synthesized by condensation polymerization between isop hthalic acid derivatives and N-substituted diethanolamines using triph enylphosphine and diethyl azodicarboxylate as the condensation reagent s in dimethyl sulfoxide (DMSO) or 1-methyl-2-pyrrolidinone (NMP). The obtained amorphous polyesters exhibited good solubility in common orga nic solvents and provided optical-quality films by spin-coating. The S HG measurements of the spin-coated films of the resulting polyesters w ere carried out by the Maker fringe method using a Q-switched Nd:YAG l aser (1064 nm) as an exciting beam after corona-poling. One of the pol yesters, which was prepared from 5-[2-(N-methyl-4-nitroanilino)ethoxy] isophthalic acid and N-[4-((4-cyanophenyl)azo)phenyl]diethanolamine, e xhibited the large second-order NLO coefficient, d(33), of 202 pm/V. O n the other hand, a polyester containing chromophore moieties with the highest density, which was prepared from nyl)azo)-N-methylanilino]-2- propyl]oxy}isophthalic acid and N-[4-((4-cyanophenyl)azo)phenyl]dietha nolamine, exhibited good temporal stability of the second-order nonlin earity at ambient temperature.