LOW DIELECTRIC-CONSTANT POLYIMIDES DERIVED FROM 1,3-BIS(4-AMINOPHENYL)ADAMANTANE

This work describes the synthesis of new adamantane-based polyimides b y reaction of 1,3-bis(4-aminophenyl)adamantane (4) with various aromat ic tetracarboxylic dianhydrides (5). The films have low dielectric con stants ranging from 2.76 to 2.92. The poly(amic-acid)s 6 have inherent viscosities of 0.98 similar to 1.42 dL/g. The polyimide 7(d) is solub le in o-chlorophenol, m-cresol, chloroform and cyclohexanone. The inhe rent viscosity and number-average molecular weight of polyimide 7(d) i s 0.61 dL/g and 45 000, respectively. The films from 7 have tensile st rengths of 69.7 similar to 110.8 MPa, elongation to breakage values of 2.1 similar to 11.3%, and initial moduli of 2.0 similar to 2.3 Gpa. D ynamic mechanical analysis (DMA) reveals that most polyimides 7 have t wo transitions. However, another subglass transition appears at 300 de grees C in the extremely rigid polyimide 7(a). The glass transition te mperatures of most polyimides 7, except 7(e) and 7(f), exceed 360 degr ees C according to DMA and DSC.