Low dielectric constant polyimides derived from 1,3-bis(4-aminophenyl)adamantane

This work describes the synthesis of new adamantane-based polyimides by reaction of 1,3-bis(4-aminophenyl)adamantane (4) with various aromatic tetracarboxylic dianhydrides (5). The films have low dielectric constants ranging from 2.76 to 2.92. The poly(amic-acid)s 6 have inherent viscosities of 0.98∼1.42 dL/g. The polyimide 7 d is soluble in o-chlorophenol, m-cresol, chloroform and cyclohexanone. The inherent viscosity and number-average molecular weight of polyimide 7 d is 0.61 dL/g and 45 000, respectively. The films from 7 have tensile strengths of 69.7-110.8 MPa, elongation to breakage values of 2.1∼11.3%, and initial moduli of 2.0-2.3 GPa. Dynamic mechanical analysis (DMA) reveals that most polyimides 7 have two transitions. However, another subglass transition appears at 300°C in the extremely rigid polyimide 7 a . The glass transition temperatures of most polyimides 7, except 7 e and 7 f , exceed 360 °C according to DMA and DSC.