Heat‐resistant polyimides and polyamides prepared from 2, 7‐diamino‐9‐dicyanomethylene‐fluorene

Abstract

SYNOPSIS9-Fluorenone was nitrated with fuming nitric acid to yield 2,7-dinitro-fluorenone (1). It was condensed with malononitrile in the presence of glacial acetic acid and a catalytic amount of piperidine to afford 2,7-dinitro-9-dicyanomethylene-fluorene (2). It was catalytically hydrogenated to the corresponding diamine (3). The latter was used as starting material for the preparation of new polyimides and polyamides bearing dicyanomethylene units. In addition, a bismaleimide was synthesized from the reaction of 3 with maleic anhydride and subsequent cyclodehydration of the intermediate bismaleamic acid. The FT-IR spectra of polymers were in agreement with those of the synthesized model compounds. The polymers and bismaleimide yielded crosslinked resins upon curing at 300°C for 40 h in the presence of a catalytic amount of 4,4'-diaminodiphenylmethane. They were stable up to 355-430°C in N2 or air and afforded anaerobic char yield of 52%57% at 800°C. 0

Preparation and characterization of bismaleimides containing ether bonds

“…The cured resins of bismaleimides, however, are extremely brittle because of their high crosslink density [8,9]. We have synthesized new bismaleimides containing ether bonds.…”