Polyisocyanate prepolymers prepared from rigid polyaromatic precursor materials, and polyurethanes prepared therefrom

A polyurethane and/or polyurea polymer prepared in the reaction of an active hydrogen-containing composition with a liquid prepolymer composition containing free isocyanate groups which comprises the reaction product of a stoichiometric excess of a polyisocyanate and an polyaromatic active hydrogen-containing compound which is represented by the structure ##STR6## wherein each D is independently an inert substituent group which, when ortho to the--A--linkage, can form a cyclic structure with the--A--linkage and the aromatic rings, b is a number from about 1 to about 10, each z is independently an active hydrogen-containing group, each R is independently a divalent radical which is inert to the reaction of the isocyanate-reactive polyphenylene compound with a polyisocyanate, and A is a covalent bond or a rigid linking group, or forms a cyclic structure with the aromatic rings and the groups D ortho to the--A--linkage.