Polymers and copolymers of formula I: in which m is typically 30 to 500 and n is 0 to 500; Ar is for example, 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, or 2,6-pyridylene; Ar2 and Ar3 are selected from various bivalent aryl and heteroaryl groups; and X is for example, the bivalent SO2 or CO. have high temperature properties which make them useful as films, matrices in carbon fiber reinforced composites and high performance adhesives; processes for preparing the polymers and copolymers employ a novel C—N coupling reaction.