Molecular and Structure-Properties Comparison of an Anionically Synthesized Diblock Copolymer of the PS--PI Sequence and Its Hydrogenated or Sulfonated Derivatives.

An approach to obtaining various nanostructures utilizing a well-studied polystyrene--poly(isoprene) or PS--PI diblock copolymer system through chemical modification reactions is reported. The complete hydrogenation and partial sulfonation to the susceptible carbon double bonds of the PI segment led to the preparation of [polystyrene--poly(ethylene--propylene)] as well as [polystyrene--poly(sulfonated isoprene--isoprene)], respectively. The hydrogenation of the polyisoprene block results in enhanced segmental immiscibility, whereas the relative sulfonation induces an amphiphilic character in the final modified material. The successful synthesis of the pristine diblock copolymer through anionic polymerization and the relative chemical modification reactions were verified using several molecular and structural characterization techniques. The thin film structure-properties relationship was investigated using atomic force microscopy under various conditions such as different solvents and annealing temperatures. Small-angle X-ray scattering was employed to identify the different observed nanostructures and their evolution upon thermal annealing.