Synthesis and properties of novel polyurethanes containing 2,4-dioxybenzylidenecyanoacetate group as a NLO-chromophore for electro-optic applications

SummaryMethyl 2,4-bis-(2'-hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 2,4-bis-(2'-vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4-toluenediisocyanate, 3,3'-dimethoxy-4,4'-biphenylene-diisocyanate, and 1,6-hexamethylenediisocyanate to yield polyurethanes 4–6 containing the NLO-chromophore 2,4-dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and DMF. Polymers 4–6 showed a thermal stability up to 280°C in TGA thermograms with Tg values obtained from DSC thermograms in the range of 66–114°C. The SHG coefficients (d33) of poled polymer films were around 7.8 × 10−9 esu.