Synthesis and properties of fluorinated semi–alicyclic transparent polyimide films for optocommunication applications

Three alicyclic dianhydrides,1,2,3,4-cyclobutanetetracarboxylic dianhydride(CBDA,Ⅰ),1,2,4,5-cyclopentanetetracarboxylic dianhydride(CPDA,Ⅱ),and 1,2,4,5-cyclohexane tetracar- boxylic dianhydride(CHDA,Ⅲ) were polymerized with two aromatic diamines,1,4-bis(4-amino-2- trifluoromethylphenoxy) benzene(6FAPB,a) and 4,4'-bis(4-amino-2-trifluoromethyl phenoxy) biphenyl (6FBAB,b) respectively,via a two-step polycondensation procedure to afford two series of fluorinated semi-alicyclic polyimides(PIs).The PIs showed good thermal stability with the initial thermal decompos- ing temperatures higher than 450℃in nitrogen and glass transition temperatures higher than 250℃.The PI films exhibited good optical transparency in the visible light region(450-700 nm) with the transmittance higher than 88% at 450 nm.The PI films showed little absorption at the optocommunication wavelengths of 1.30μm and 1.55μm.