Sul-containing fluorinated polyimides for optical waveguide device

Novel sul-containing fluorinated polyimides have been synthesized by the reaction of 2,2'-bis-(trifluoromethyl)-4,4'-diaminodiphenyl sulfide (TFDAS) with 1,4-bis-(3,4-dicarboxyphenoxy)benzene dianhydride (HQDPA), 2,2'-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4,4'-oxydiphthalicanhydride (ODPA) or 3,4,3',4'-biphenyl-tetracarboxylic acid dianhydride (s-BPDA). The fluorinated polyimides, prepared by a one-step polycondensation procedure, have good solubility in many solvents, such as N-methyl-2-pyrrolidinone (NMP), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cyclohexanone, tetrahydrofuran (THF) and m-cresol. The molecular weights (M-n's) and polydispersities (M-n/M-w's) of polyimides were in the range of 1.24 x 10(5) to 3.21 x 10(5) and 1.59-2.20, respectively. The polymers exhibit excellent thermal stabilities, with glass-transition temperatures (T-g) at 221-275 degrees C and the 5% weight-loss temperature are above 531 degrees C. After crosslinking, these polymers show higher thermal stability. The films of polymers have high optical transparency. The novel sul-containing fluorinated polyimides also have low absorption at both 1310 and 1550 nm wavelength windows. Rib-type optical waveguide device was fabricated using the fluorinated polyimides and the near-field mode pattern of the waveguide was demonstrated. (C) 2008 Elsevier B.V. All rights reserved.