| 초록 |
Amorphous polymers with high concentrations of dipole moments exhibit piezoelectric properties after poling. A potentially piezoelectric polymer must have a large concentration of dipoles. We have recently proposed that three- and four-membered rings with several cyano substituents held rigidly in alignment will have large dipole moments and these polymers are potential piezoelectric materials. The present report describes the synthesis of polyurethanes containing tricyanocyclopropyl group. We selected tricyanocyclopropane as a piezoelectric chromophore because it has larger dipole moment and expected to exhibit higher piezoelectric activity. To verify this fact, molecular modeling calculations were performed on the compound 4 using atom superposition and electron delocalization molecular orbital (ASED-MO). 1-(2,2,3-Tricyano-3-carbomethoxycyclopropyl)-2,5-di-(2-hydroxyethoxy)benzene (4) was prepared by the reaction of bromomalononitrile with 2,5-di-(2-hydroxyethoxy)benzylidenecyanoacetate (3>). The dipole moment of diol 4, calculated by ASED-MO method, was 8.29 D. Diol 4 was condensed with 2,4-toluenediisocyanate and 3,3-dimethoxy-4,4-biphenylenediisocyanate to yield T-type polyurethanes 5-6 containing tricyanocyclopropane functionalities in the pendant group. The resulting polymers 5-6 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25-0.30 dL/g. Solution-cast films showed a thermal stability up to 280oC with glass-transition temperatures of 163-167oC. Study on the piezoelectric activity of poled polymer films are in progress. |
