Zinc ion induced polymorphism in macromolecular self-assembly of diblock copolymers

A novel interconnected cylindrical micellar network was prepared from a diblock copolymer, poly(maleic anhydride-alt-styrene)-b-polystyrene, in ethanol under a self-assembly directing agent: Zn2+ ions. The solution containing interconnected cylindrical network is bluish and transparent, which is stable for more than 6 months at room conditions without any observable macroscopic phase separation. In aqueous solution, however, hydrolysis of the anhydride yields hydrophilic carboxyl groups, which result in formation of uniform positive spherical micelles from the same diblock polymer. The nanostructures of both the spherical micelles and cylindrical assemblies are characterized with light scattering and transmission electron microscopy (TEM).