Synthesis and electro-optical properties of novel Y-type polyurethanes containing dioxynitrostilbene

3,4-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (2) was prepared by the reaction of 2-iodoethanol with 3,4-dihydroxy-4'-nitrostilbene. Diol 2 was condensed with 2,4-toluenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylenediisocyanate and 1,6-hexamethylenediisocyanate to yield novel Y-type polyurethanes 3-5 containing dioxynitrostilbene as a non-linear optical (NLO)-chromophore. Polymers 3-5 were soluble in common organic solvents, such as acetone and DMF. These polymers showed thermal stability up to 280degreesC in TGA thermograms with T-g values in the range of 100-143degreesC in DSC thermograms. The approximate lengths of aligned NLO-chromophores of the polymers estimated from AFM images were around 2 nm. The SHG coefficients (d(33)) of poled polymer films were around 4.5 x 10(-8) esu. Poled polymer films had improved temporal and long-term thermal stability owing to the hydrogen bonding of urethane linkage and the main-chain character of the polymer structure, which are acceptable for NLO device applications. (C) 2004 Society of Chemical Industry.