Synthesis of novel poly(vinyl ether)s containing the oxybenzylidenemalononitrile group as a nonlinear optical chromophore, and their electro-optic properties

Abstract

2,4-Di-(2′,2′-dicyanovinyl)-1-(2′-vinyloxyethoxy)benzene and 2,4-di-(2′-carbomethoxy-2′-cyanovinyl)-1-(2′-vinyloxyethoxy)benzene were prepared by condensation of 4-(2′-vinyloxyethoxy)isophthaldehyde with malononitrile and methyl cyanoacetate, respectively. The two vinyl monomers were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ether)s containing two oxybenzylidenemalononitrile and oxybenzylidenecyanoacetate groups, which are effective chromophores for second-order nonlinear optical applications. These polymers were soluble in common organic solvents such as acetone and dimethyl sulforide. They showed thermal stabilities up to 300 °C from thermogravimetric analysis (TGA), with differential scanning calorimeter (DSC) thermograms giving Tg values in the range 73–87 °C. The second harmonic generation (SHG) coefficients (d33) of poled polymer films were around 1.8 × 10−9 esu, and these polymers showed good long-term thermal stability for 60 days at room temperature, which is acceptable for nonlinear optical (NLO) device applications. Copyright © 2004 Society of Chemical Industry