SYNTHESIS AND CHARACTERIZATION OF NEW ADAMANTANE-BASED POLYIMIDES

A new adamantane-based dietheramine, 2,2-bis[4-(4-aminophenoxy)phenyl] adamantane, was prepared in two steps from chloro displacement of p-c hloronitrobenzene with the potassium phenolate of 2,2-bis(4-hydroxyphe nyl)adamantane, followed by hydrazine catalytic reduction of the inter mediate dinitro compound. A series of polyimides with the adamantane-2 ,2-diyl unit as a cardo group was prepared from the adamantane-based d ietheramine and various aromatic dianhydrides by a conventional two-st age synthesis in which the poly(amic acid)s obtained in the first stag e were heated stage-by-stage at 150-270 degrees C to give the polyimid es. The intermediate poly(amic acid)s had inherent viscosities between 0.82 and 1.66 dL/g. Except for the polyimide from pyromellitic dianhy dride, all of the polyimides could be dissolved in NMP, and several po lyimides also showed good solubility in other organic solvents. All of the polyimides were amorphous in nature as evidenced by X-ray diffrac tograms. The glass-transition temperatures (T-g) of these polyimides w ere recorded between 248 and 308 degrees C by differential scanning ca lorimetry (DSC), and the softening temperatures (T-s) determined by th ermomechanical analysis (TMA) stayed in the range of 254-335 degrees C . Decomposition temperatures for 10% weight loss all occurred above 50 0 degrees C in both air and nitrogen atmospheres.