Three novel narrowly distributed rod-coil diblock copolymers, poly(styrene-block-(2,5-bis-[4-methoxyphenyl]oxycarbonyl)styrene) (PS-b-PMPCS), with same PS block length and different PMPCS lengths, were synthesized by 2,2,6,6-tetramethyl-1-piperidinyloxy- (TEMPO-) mediated living free radical polymerization. The self-assembly behavior of the block copolymers in p-xylene, which is a good solvent for the PS coils and a selective solvent for the PMPCS rods, was studied by dynamic and static laser light scattering (LLS) and transmission electron microscopy (TEM). The critical association concentration (CAC) for each copolymer was determined and was found to decrease as the molecular weight of the rods increases. We found that the molar mass of the self-assembled nanostructures increased very fast near CAC, while this slows at concentrations much higher than CAC. Dynamic and static LLS revealed that the block copolymers formed core-shell nanostructure in the concentrations we observed, and the radius of the core was calculated. The core-shell nanostructure was also confirmed by TEM images. The calculated radius of the core was compared to the TEM results, and it was found to be compatible.