| 초록 |
New unsymmetrical diamine monomer containing both bezimidazole-ring and trifluoromethyl group, 6,4'-diamino-2'-trifluoromethyl-2-phenylbenzimidazole, was prepared and polymerized with PMDA, BPDA, BTDA, and ODPA by using one-pot synthetic method to obtain corresponding polyimides. All the rigid rod-like polyimides except the polyimide from PMDA were soluble in polar aprotic solvents. Incorporation of trifluoromethyl groups unsymmetrically in the rigid polyimides improved their solubility without decreasing their physical properties. The polymers showed high glass transition temperature (Tg = 289-368 oC), high thermal stability (Td5 ＞ 500 oC), and relatively low coefficient of thermal expansion (CTE = 17.8-46.4 ppm/oC) due to their rigid-rod like structure. Also, they showed low refractive indexes (n=1.64-1.68) and low birefringence (0.02) due to the trifluoromethyl pendent groups.
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