LOW DIELECTRIC-CONSTANT POLYIMIDES DERIVED FROM NOVEL 1,6-BIS[4-(4-AMINOPHENOXY)PHENYL]DIAMANTANE

This work reports the synthesis and characterization of diamantane-bas ed polyimides obtained from 1,6-bis [4-(4-aminophenoxy)phenyl] diamant ane and various aromatic tetracarboxylic dianhydrides. This novel poly imide exhibits a low dielectric constant (2.56-2.78), low moisture abs orption (<0.292%), good solubility, and high number-average molecular weights (M-n: 3.7 x 10(4) to 12.8 x 10(4)). This kind of diamantane-ba sed polyimide can form a tough and transparent film after cyclodehydra tion. The films have tensile strengths of 74.4-118.2 MPa, elongations to break of 5.2-24.3%, and initial moduli of 1.9-2.2 GPa. Dynamic mech anical analysis (DMA) reveals that there is subglass relaxation above 300 degrees C for structures 7a, 7d, and 7g, which is unusual for most of the typical polyimides. This type of novel diamantane-based polyim ide is very promising for electronic applications due to its good mech anical properties, good thermal stability, low dielectric constant, an d low moisture absorption.