For several decades, block copolymer with broad molecular weight distribution (MWD) has been interested due to its influence on processability and block copolymer self-assembly such as phase behavior and microdomain periodicity. However, new controlled synthetic methods for diblock copolymers and the properties of polydisperse diblock copolymers are still required to control the dispersities and composition of a distribution. In this thesis, we report the synthesis and characterization of poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers where dispersity in both blocks are varied systematically. The PS and PMMA homopolymers are synthesized via controlled free radical polymerization, and their block dispersities are varied by manipulating either initiator feed rate or chain transfer agent addition rate. The desired diblock copolymers are then obtained by coupling the azido-end functionalized PS and alkyne-end functionalized PMMA homopolymers of desired dispersity via click reaction. For the domain spacing and morphology characterization, the synthesized PS-b-PMMA diblock copolymers are analyzed by SAXS and AFM.