Synthesis And Proerties Of Novel Aromatic Poly-Amides Containing 2,6-Diphenyl-4-arylpyridine Units Or Cardo Groups In The Main Chains And Pendant Trinuoromethyl Groups

This thesis mainly reviews the synthetic method and development of aromatic polyamides. In order to further improve the performance of aromatic polyamides, we synthesized a series of novel aromatic polyamides containing 2,6-diphenyl-4-arylpyridine units or cardo groups in the main chains and pendant trifluoromethyl groups by incorporating both 2,6-diphenyl-4-arylpyridine units or cardo groups and trifluoromethyl side groups into the polyamide backbone. This thesis mainly consists of three parts as follow:1. Three aromatic diamines containing 2,6-diphenyl-4-arylpyridine unit were prepared from 1-naphthaldehyde, 2-naphthaldehyde and p-(trifluoromethyl)benzaldehyde via improved Chichibabin pyridine synthesis reaction with p-nitroacetophenone, followed by reduction with hydrazine hydrate using Pd/C as catalyst. We synthesized a series of novel aromatic polyamides containing 2,6-diphenyl-4-arylpyridine units in the main chains and pendant trifluoromethyl groups by low temperature solution polycondensation of these aromatic diamines with di-aroyl chlorides with pendant trifluoromethyl group in DMAc. The inherent viscosities of polymers obtained are above 0.5 d L/g and they were soluble in strong polar solvents such as DMAc and NMP at room temperature. These polymers exhibited high thermal stability and good mechanical properties. The glass transition temperatures of these polymers were in the range of 270-314 oC and the decomposition temperatures at 5% weight loss were in the range of 370-428 oC. These polymer films had good optical transparency and lower dielectric constants(100Hz, 3.26-4.41).2. Four aromatic diamines containing cardo groups were prepared from 4,4'-(9Hfluorene-9,9-diyl)diphenol and 4,4'-(9H-xanthene-9,9-diyl)diphenol via the condensation with 4-chloronitrobenzene, 2-chloro-5-nitro-(trifluoromethyl)benzene, followed by reduction with hydrazine hydrate using Pd/C as catalyst. We synthesized a series of novel aromatic polyamides containing cardo groups in the main chains and pendant trifluoromethyl groups by low temperature solution polycondensation of these aromatic diamines with di-aroyl chlorides with pendant trifluoromethyl group in DMAc. The inherent viscosities of resulting polymers are above 0.65 d L/g and they were soluble in strong polar solvents such as DMAc and NMP at room temperature. These polymers exhibited high thermal stability and good mechanical properties. The glass transition temperatures of these polymers were in the range of 241-258 oC and the decomposition temperatures at 5% weight loss were in the range of 431-470 oC. These polymer films had good optical transparency and lower dielectric constants(100Hz, 2.96-4.75).3. A series of aromatic copolyamides containing fluorene groups in the main chains and pendant trifluoromethyl groups were synthesized via low temperature solution copolycondensation of 9,9-di[4-(4-aminophenoxy)phenyl]fluorine, 4,4'-diaminodiphenyl ether with 5-(4-trifluoromethylphenoxy)isophthaloyl chloride by varying the molar ratio of 9,9-di[4-(4-aminophenoxy)phenyl]fluorine to 4,4'-diaminodiphenyl ether. The inherent viscosities of resulting polymers are above 0.65 d L/g and they were soluble in strong polar solvents such as DMAc and NMP at room temperature. These polymers exhibited high thermal stability and good mechanical properties. The glass transition temperatures of these polymers were in the range of 249-261 oC and the decomposition temperatures at 5% weight loss were in the range of 417-450 oC. These polymer films had good optical transparency and lower dielectric constants(100Hz, 3.25-5.02).