Thermally Stable Polyarylenes with Low Dielectric Constant: Direction towards the Lowest Limit of Dielectrics

Abstract

We successfully prepared a series of soluble, thermally stable Polyarylenes with low dielectric constant (k) by coupling polymerization of aromatic dihalides and/or bismesylates of the corresponding bisphenols using Zn and Ni-phosphine catalysts. Among the non-fluorinated polyarylenes, a soluble copolyarylene derived from bismesylates of 9, 9-bis(4-hydroxyphenyl)fluorene and 4, 4′-dihydroxyphenyl-diphenylmethane showed with k=2.7 (@1MHz), Tg:>300°C, and Td (5%, N₂):549°C the lowest k value. The polyarylene with the lowest k, a fluorinated polymer prepared from the bismesylate of 2, 2-bis-(4-hydroxyphenyl)hexafluoropropane, showed k=2.2 (@1MHz), Tg:249°C and Td (5%, N₂):508°C. Among organic polymers, soluble polyarylenes proved to be very promising as low k materials with high thermal stability. In addition, we show based on these new results and previous results with fluorenyliden-substituted polyimides how to estimate the dielectric constant in polyimides and polyarylenes as a function of polar linkage (imide) concentration and fluorine content.