Synthesis of Novel Polyurethanes Containing Tricyanocyclopropyl Group as a Piezoelectric Chromophore and Their Properties

摘要

1-(2`,2`,3`-Tricyano-3-carbomethoxycyclopropyl)-3,4-di-(2`-hydroxyethoxy)benzene (4) was prepared by the reaction of bromomalononitrile with methyl 3,4-di-(2`-hydroxyethoxy)benzylidenecyanoacetate (3). Diol 4 was condensed with tolylene-2,4-diisocyanate, 3,3`-dimethoxy-4,4`-biphenylenediisocyanate, and 1,6-hexamethylenediisocyanate to yield polyurethanes 5, 6, and 7 containing tricyanocyclopropane functionalities in the pendant group. The resulting polymers 5-7 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25-0.30 dL/g. Polyurethanes 5-7 showed a thermal stability up to 300 ∩ in TGA thermograms. Solution-cast films showed T_g values in the range of 100-125 ∩ and piezoelectric coeffcients (d₃₁) of the poled polymer films were 1.3-2.0 pC/N, which are acceptable for piezoelectric device applications.