Eu(3+)-induced aggregates of diblock copolymers and their photoluminescent property

A general protocol to prepare photoluminescent polymeric aggregates with multiple morphological structures was proposed in this article. The amphiphilic diblock copolymer, polystyrene-block-poly (acrylic acid) (PS-b-PAA) which acted as the polymer ligand, was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Eu(3+) ions were selected as the cross-linkers to coordinate with the carboxyl groups along PAA segments of the diblock copolymer, resulting in cross-linked PAA networks as the core. At the same time, PS coronas still kept their solubility to the solvent phase, preventing the precipitation of the complex. The obtained aggregates dispersed well in dimethyl formamide (DMF) instead of precipitation occurred in complex systems between non-block copolymers and lanthanide ions. It is the first time that the aggregates with rich morphological structures, including ordinary micelles, rod-wrapped micelles, sun-shaped micelles, vesicles and large compound micelles (LCMs), were obtained by adjusting the molar ratio or the concentration of Eu(3+) ions and diblock copolymer. Importantly, the aggregates have enhanced photoluminescent properties via the coordination between Eu(3+) and diblock copolymer at their optimal ratio. The obtained aggregates are convenient for further processing, such as spin-coating and casting. This strategy can also be applied to other coordination systems between diblock copolymers and lanthanide ions.