Synthesis of 1,4-Bis(3-amino-5-trifluoromethylphenoxy)Benzene and Properties of the Polyimide Film Therefrom

Firstly, 1,4-bis(3-nitro-5-trifluoromethylphenoxy)benzene(I) was synthesized through the nucleophilic substitution reaction of 3,5-dinitrobenzotrifluoride and 1,4-dihydroxybenzene in the presence of potassium carbonate. Then, the diamine monomer 1,4-bis(3-amino-5-trifluoromethylphenoxy)benzene (II) was obtained through the catalytic reduction with hydrazine and Pd/C. These fluorinated polyimides (PI) were synthesized from the fluorinated diamine II with four kinds of dianhydrides, including pyromellitic dianhydride (PMDA), 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3’,4,4’-oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-benzophenonetetracarboxylicdianhydride (BTDA) respectively, via thermal imidization of poly(amic acid) (PAA). The structure and properties of these obtained fluorinated PIs were characterized. These experimental results showed that these fluorinated PI films exhibited excellent optical transmittance in the visible region and thermal resistance. The PI derived from ODPA showed the best optical transparency with the transmittance higher than 85.38 % at 450 nm. These PIs also exhibited good thermal properties with 5 wt% thermal decomposition temperature above 533 °C.