Strategy to achieve ultralow dielectric constant for polyimide: introduction of fluorinated blocks and fluorographene nanosheets by in situ polymerization

Fluorographene (FG) nanosheets have been prepared successfully by the exfoliation of fluorinated graphite. Then, different mass ratios of FG were added into the precursor of polyimide containing fluorinated blocks (FPI) to prepare FG/FPI composite films via in situ polymerization. The effects of the addition of FG on the morphological, mechanical, thermal and dielectric properties of the composite films are investigated. It's found that the neat FPI matrix itself shows a dielectric of 2.92 (1 kHz), lower than that of traditional polyimide, which is about 3.6 (1 kHz). When the FG content reaches 0.5 wt%, a flexible, transparent composite film is obtained with a dielectric constant as low as 1.77 (1 kHz) and loss tangent of 0.005 (1 kHz). The dielectric constant of the FG/FPI composite film is lower than those reported in previous studies and therefore the dielectric film is a potential candidate to be used in microelectronic fields.