Chain Length Recognition: Core-Shell Supramolecular Assembly from Oppositely Charged Block Copolymers

Molecular recognition based on length was found to occur between oppositely charged pairs of flexible and randomly coiled block copolymers in an aqueous milieu. Matched pairs with the same block lengths of polyanions and polycations exclusively formed even in mixtures with different block lengths. These assemblies of the charged segments with matched chain lengths then formed larger core-shell–type supramolecular assemblies with an extremely narrow size distribution due to the strict phase separation between core- and shell-forming segments.