Low dielectric constant of soluble polyimides containing diisopropyl, trifluoromethyl, and methyl structures

To further improve the solubility, film formation ability and dielectric properties of polyimides, an aromatic diamine and its polyimides (<b>PI 3a∼3e</b>) containing diisopropyl, trifluoromethylandmethyl structures were successfully synthesized based on molecular structure design and modification. The relationship between the chemical structure and properties of <b>PI 3a∼3e</b>wassystematically investigated. It is found that the introduction of various structural modification units has effectively improved some properties of the polymers. <b>PI 3a∼3e</b> can be dissolved in both high and low boiling solvents and show good film formation ability. When the frequency is 1 MHz, their dielectric constant (D_k) and dielectric loss (D_f) are reduced to the ranges of 2.49 ∼ 2.86 and 0.00547 ∼ 0.00691, respectively. In addition, these modified polyimide films have high thermal and mechanical properties and also exhibit low water absorption and hydrophobic properties.