monomers having the formula x 1 — ar 1 -— ar 2 - x 2 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 x 1 and x 2 are the same or different polymerizable groups and wherein ar 1 and ar 2 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 .