Bis(maleimido) phenoxy phenylphosphine oxide

Bis(maleimido) phenoxy phenylphosphine oxide monomers are formed by reacting a bis(aminophenoxyphenyl) phosphine oxide, e.g., bis(3-aminophenoxy) triphenylphosphine oxide, with maleic anhydride forming the intermediate bismaleamic acid species which is cyclodehydrated to the desired bismaleimido compound. The improved properties include: (1) a low melting point (T.sub.m =90.degree. C.); (2) a wide processing temperature range (T.sub.cure =210.degree. C.); and (3) a high T.sub.g value of 400.degree. C.; and (4) a high char yield which suggests flame resistance.