On the nano-morphology and dielectric properties of 6FXDA/6FDAm based polyimide nanofoams

A polyimide triblock copolymer, based on 9,9-bis(trifluoromethyl)xanthenetetracarboxylic dianhydride (6FXDA), 2,2-bis(4-aminophneyl)hexafluoropropane (6FDAm) and poly(propylene oxide) (PO) was foamed to yield polyimide nanofoams with low permittivity. Microphase separated nano-domains were observed for the 6FXDA/6FDAM-PO copolymer films. The domain shapes were irregular due to the nature of non-equilibrium processing conditions. The size of the irregularity increased with foaming. The measured dielectric constant was decreased to ca. 2.3 for foamed polyimide with 24% PO initial incorporation as compared with ca. e′ to approximately 2.6 for the 6FXDA/6FDAm homopolymer.