Polyion complex (PIC) micelles formed from oppositely charged styrene-based polyelectrolytes via electrostatic, hydrophobic, and π-π interactions

Polyion complex (PIC) micelles were fabricated by directly mixing aqueous solutions of oppositely charged diblock copolymers, poly(2-(methacryloyloxy) ethylphosphorylcholine)-block-poly(vinylbenzyl trimethylammonium chloride) (PMPC-b-PVBTAC; P91V100) and PMPC-block-poly(sodium p-styrenesulfonate) (PMPC-b-PNaSS; P91N100). Cationic and anionic diblock copolymers were synthesized via controlled/living radical polymerization using the poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) macrochain transfer agent. The subscript number represents the degree of polymerization (DP) of each block. A pair of oppositely charged diblock copolymers was mixed in an aqueous medium to prepare the PIC micelle using electrostatic, hydrophobic, and pi-pi interactions. The PIC micelles attained the maximum size and aggregation number when the charges of the cationic and anionic blocks were neutralized. The spherical core-shell micelle structure of the PIC micelle was confirmed. Generally, upon the addition of salt to the PIC micelle aqueous solution, the micelles dissociated because of the screening effect. However, the P91V100/P91N100 PIC micelle was stable against NaCl because the PVBTAC/PNaSS core of the PIC micelle was formed by electrostatic, hydrophobic, and pi-pi interactions. The P91V100/P91N100 PIC micelle can encapsulate charged and hydrophobic guest molecules.

Automated summary

Polyion complex (PIC) micelles were prepared by mixing aqueous solutions of oppositely charged diblock copolymers. The micelles exhibited a stable core-shell structure and were able to encapsulate charged and hydrophobic guest molecules.