Monomers having the formula X1—Ar1-[triarylamine]—Ar2-X2 wherein the triarylamine unit comprises at least one nitrogen atom in the backbone of the monomer and at least three substituted or unsubstituted aryl or heteroaryl groups and wherein X1 and X2 are the same or different polymerizable groups and wherein Ar1 and Ar2 are the same or different substituted or unsubstituted aryl or heteroaryl groups. Polymers and copolymers comprising such monomers are also described. The polymers have particular application in organic optoelectronic devices such as organic electroluminescent devices and organic photovoltaic devices.