| 초록 |
In the developments of nonlinear optical (NLO) polymers for electro-optic device applications relaxation of electrically induced dipole alignment is important consideration. Two approaches to minimize the randomization have been proposed. One is to use crosslinked system and the other is to use a high glass transition temperatures (Tg) polymers such as polyimides. Polyimides are one of promising NLO materials because of their high Tgs which can be utilized to stabilize the dipole orientation of the NLO chromophore at high temperature. Another advantage of polyimides is their high thermal stability that enables them to survive at high temperatures during fabrication and operation in electro-optic devices. In this work we prepared novel soluble polyimides containing dioxynitrostilbene as a NLO-chromophore. 2,3-Di-(2-hydroxyethoxy)-4-nitrostilbene (2) was prepared by the reaction of iodoethanol with 2,3-dihydroxy-4-nitrostilbene (1). Diol 2 was reacted with trimellitic anhydride chloride to yield 2,3-bis-(3,4-dicarboxyphenylcarboxyethoxy)-4-nitrostilbene dianhydride (3). Compound 3 was reacted with 1,4-phenylenediamine, 4,4-oxydianiline, and 4,4-diaminobenzanilide to give polyimides 4-6, respectively, containing the NLO-chromophore 2,3-dioxynitrostilbenyl group. The chemical structure of the polymers was confirmed by 1H NMR, IR spectra, and elemental analysis. The resulting polyimides 4-6 were soluble in polar solvents such as acetone and DMF. Polymers 4-6 showed a thermal stability up to 300oC in TGA thermograms. Tg values obtained from DSC thermograms were in the range of 137-162oC. Study on the SHG activities, film morphology, and electro-optic properties of the polymers are under progress. |
