A new series of liquid crystalline diblock copolymers composed of a polystyrene and a polymethacrylate with an azobenzene moiety in the side chain were synthesized through atom transfer radical polymerization and characterized by various techniques. Photoinduced birefringence of diblock copolymers and the azobenzene homopolymer was investigated and compared under different excitation conditions. The results show that the microdomain structures characteristic of diblock copolymers hinder the photoalignment of azobenzene mesogenic groups.