Low Dielectric Constant Polyimides Derived from Novel 1,6-Bis[4-(4-aminophenoxy)phenyl]diamantane

This work reports the synthesis and characterization of diamantane-based polyimides obtained from 1,6-bis[4-(4-aminophenoxy)phenyl]diamantane and various aromatic tetracarboxylic dianhydrides. This novel polyimide exhibits a low dielectric constant (2.56−2.78), low moisture absorption (<0.292%), good solubility, and high number-average molecular weights ( M n: 3.7 × 10 4 to 12.8 × 10 4 ). This kind of diamantane-based polyimide can form a tough and transparent film after cyclodehydration. 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 mechanical analysis (DMA) reveals that there is subglass relaxation above 300 °C for structures 7a, 7d, and 7g, which is unusual for most of the typical polyimides. This type of novel diamantane-based polyimide is very promising for electronic applications due to its good mechanical properties, good thermal stability, low dielectric constant, and low moisture absorption.