Preparation and properties of new polyimides derived from 1,6-diaminodiamantane

New polyimides containing diamantane units were prepared by a conventional two-step method starting from 1,6-diaminodiamantane and aromatic dianhydrides. The intermediate poly(amic acid)s had inherent viscosities of 0.33–0.55 dL/g. These polyimides did not decompose below 400°C in air or nitrogen atmosphere, and the temperature at 5% weight loss were above 491°C. The glass transition temperatures of the polyimides were found to be 375–429°C by DSC. These polyimides had almost the same semicrystalline patterns and exhibited crystalline diffraction peak (2 θ) at around 15°. The polyimide Vb exhibited a melting endothermic peak at 514°C.