Synthesis of diol monomers and organosoluble fluorinated polyimides with low dielectric

Abstract

Four diimide–diol monomers were synthesized from 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride and aminophenol/aminonaphthol. The structures of the monomers were characterized by spectroscopic analysis. A series of fluorinated polyimides (FPI-1 to FPI-8) were synthesized from these new diols and 4,4′-difluorobenzophenone/4,4′-dichlorodiphenyl sulphone, through nucleophilic displacement reaction. The FPIs were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, X-ray diffraction, thermogravimetry, differential scanning calorimetry, solution viscosity, solubility test, and dielectric properties test. FPIs were amorphous and showed good solubility due to the presence of >C(CF3)2 unit and flexible groups in the polyimides backbone. These FPIs also showed good thermal stability and the 10% weight loss occurred in the range 353–505°C. The limiting oxygen index values of FPIs were in the range of 31.5–39.1 and such FPIs can be used as self-extinguishing polymers. These FPIs have a dielectric constant in the range of 3.10–4.23 and can be used as high temperature electrical insulation materials.