A novel aromatic diamine containing fluorine and thioether groups

4

4'-bis(4-amino-2- (trifluoromethyl)phenylsulfanyl)diphenyl sulfide (6FSDEA)

was synthesized by the condensation and reduction reaction with 1-chloro-4-nitro-2-(trifluoromethyl)benzene and 4

4'-thiobisbenzenethiol as starting material.Then it was polymerized with six various dianhydrides

including BPDA

ODPA

BTDA

6FDA

DSDA and DTDA via one-pot polycondensation to produce a series of novel polyimides.The polyimides are soluble in conventional polar organic solvents

such as NMP

DMF

DMAc

m-cresol

and some of them are even soluble in CDCl3 and acetone.The glass transition temperatures of plyimides were in the range of 197.1~235.1℃ (DMA) and 199.8~231.7℃ (DSC)

respectively.Moreover in nitrogen atmosphere the 5% and 10% weight loss temperatures were in the range of 491~535℃ and 517~557℃

respectively.And the char yields at 800℃ were between 30 wt%~63 wt%.In addition

the PI films showed good optical transparency in the visible light region (400~700 nm) with the cutoff wavelengths range of 380~417 nm

and little absorption at the optical communication wavelengths of 1310 nm and 1550 nm.Furthermore

the average refractive indices (nAV) of the polyimide films at 1310 nm and 1550 nm were 1.5401~1.6142 and 1.5389~1.6124 respectively

measured by using a Variable Angle Spectroscopic Ellipsometer.The birefringence (n) of the polyimide films at 632.8 nm were in the range of 0.0012~0.0043 obtained by the prism coupling device.The above results showed that these PIs could be used as candidates for optical waveguide materials.