Multiple Morphologies of PAA-b-PSt Assemblies throughout RAFT Dispersion Polymerization of Styrene with PAA Macro-CTA

The assembly behavior of diblock copolymers in solution can be modulated by block length, block ratio, solvent properties, and preparation route. Different assembly morphologies such as spherical micelles, cylindrical micelles, vesicles, and large compound vesicles have been obtained for diblock copolymers with shorter solvated block, such as poly(acrylic acid)-b-polystyrene (PAA-b-PSt). In the present work, we reported an easy-going route to prepare PAA-b-PSt assemblies with different morphologies through reversible addition−fragmentation-transfer (RAFT) dispersion polymerization of styrene in methanol with trithiocarbonated PAA as macromolecular chain transfer agent. Because this RAFT dispersion polymerization exhibited controlled features, the consecutive growth of PSt block led to the successive transition of the obtained PAA-b-PSt assemblies from spherical micelles, cylindrical micelles, vesicles, to large compound vesicles, confirmed by the combination of electron microscopy, laser light scattering,...