A novel fluorinated aromatic diamine monomer containing ether linkage

trifluoromethylphenyl and sulfonyl groups

2

2'-bis［3-(4-trifluoromethylphenyl)-4-(4-amino-phenoxy)phenyl］sulfone 3

was successfully synthesized through free-radical substitution

Suzuki coupling and nucleophilic substitution reactions using bis(4-fluorophenyl)sulfone and N-bromosuccinimide (NBS) as starting material

and was characterized by IR spectroscpy and 1H-NMR. Then it was employed to prepare a series of fluorinated poly-(sulfone imide)s (PSI 5a~5c ) with various commercial aromatic dianhydrides via a one-step high-temperature polycondensation. IR and 1H-NMR spectra were used to investigate the chemical structure. The results confirmed that the structure of poly(sulfone imide)s was in good agreement with the proposed structure and the imidization was conducted completely. The properties of the polymers were characterized by GPC

TGA

DSC

UV etc. The PSI polymers having number average molecular weight of 70100~80000 and molecular weight distribution of 1.44~1.70 were obtained. These poly(sulfone imide)s exhibited an excellent solubility and optical property. They could be easily dissolved not only in some strong polar organic solvents

such as N-methyl-2-pyrrolidone (NMP)

N

N-dimethylacetamide (DMAC) and N

N-dimethylformamide (DMF)

but also had good solubility in some low-boiling-point solvents

such as chloroform

dichloromethane and tetrahydrofuran (THF) at room temperature. Flexible and transparent membranes were obtained by solution casting. They gave the UV cutoff wavelengths between 366 and 330 nm and high transmittance at 450 nm. Furthermore

these poly(sulfone imide)s also showed good thermal and mechanical properties. The glass-transition temperatures (Tg) were in the range of 254~264℃ and their 10% weight loss temperatures were above 550℃ under ether nitrogen or air atmosphere. These poly(sulfone imide) films had tensile strengths of 87~92 MPa

elongations at break from 9% to 13%

and Young's modulus of 1.8~2.1 GPa. Moreover

all the films possessed good dielectric properties with low dielectric constants between 2.8 and 3.0 at 1 MHz frequency.