Polyimides Prepared from 4,4′-(2-Diphenylphosphinyl-1,4-Phenylenedioxy)Diphthalic Anhydride for Potential Space Applications

As part of an ongoing materials development activity to produce high performance polymers that are space environmentally stable, phosphine oxide containing polyimides were prepared by reacting a novel aromatic dianhydride, 4,4′-(2-diphenylphosphinyl-1,4-phenylenedioxy)diphthalic anhydride 3, with aromatic diamines. The dianhydride was prepared from 2,5-dihydroxyphenyldiphenylphosphine oxide in three steps in relatively good yield. In general, the polyimides exhibited physical and mechanical properties comparable to other wholly aromatic polyimides. Depending upon the diamine, nearly all of the polyimides formed near colorless to yellow films. The polyimides were amorphous and in most cases soluble in polar aprotic solvents. However, one polymer film prepared using 1,4-phenylenediamine exhibited some degree of ordering when prepared by chemical imidization. The chemistry, physical and mechanical properties of the polymers are discussed.