Molecular variables in the self-assembly of supramolecular nanostructures

Supramolecular structures have the potential to provide macromolecular beha vior using relatively low molar mass building blocks. We present here data on the self-assembly of triblock rodcoil molecules which contain a rigid bi phenyl ester segment covalently linked to structurally diverse oligomeric s egments. These molecules form supramolecular aggregates with molar masses i n the range 10(5)-10(6) Da, and our experiments probe how supramolecular st ructure can be manipulated by varying the volume fraction of the coillike f lexible segments with respect to that of rod segments. The oligostyrene-oli goisoprene diblock coils were synthesized via anionic polymerization and va ried in average length from (6(sty), 6(iso)) to (30(sty), 30(iso)). Small-a ngle X-ray scattering scans revealed layer spacings corresponding to monola yers that increase in size as the coil's molar mass increases. We observed that an increase in coil volume fraction reduces the thermal stability of t he supramolecular structure, but a corresponding increase in rod segment le ngth can counteract this effect. Finally the self-organized nanostructures seem to pack into a superlattice based on evidence obtained by X-ray scatte ring and transmission electron microscopy.