The ability to control the structure and function of supramolecular self-assemblies gives rise to many patterning possibilities. Making use of the interactions between the copolymers and solvent provides a neat way of controlling the structures. The pyridine residues of each of the diblock copolymer poly styrene-b-poly(4-vinylpyridine) (PS-P4VP) was selectively betainized using 1,3-propane sultone under mild conditions to yield a series of novel betaine diblock copolymers in chloroform and toluene, respectively. The solution properties were studied using dynamic light scattering, static light scattering, and H-1 NMR spectroscopy. The morphology of the resulting micellar film was studied using transmission electron microscopy. The size of the micelles formed was found to be strongly dependent on the amount of sultone grafted and the shape of PS-P4VP-sultone micelle changed from spherical to elongated with different PS-P4VP-to-sultone ratio.