A method for making a polymer containing a first repeat unit having formula: —Ar—N(R)—Ar(N(R′)—Ar)x— which may be substituted or unsubstituted where x or 0 or 1; each Ar is the same or different and independently is a substituted or unsubstituted aryl or heteroaryl group and R and R′ each is hydrogen or a substituent group and a second repeat unit that is the same or different from the first repeat unit and comprises a substituted or unsubstituted, aryl or heteroaryl group.