Polyion Complex (PIC) Flower-shaped Nano-micelles formed from Anionic Triblock and Cationic Diblock Copolymers

Abstract

Poly (sodium 2-(acrylamido)-2-methylpropanesulfonate)-block-poly(ethylene glycol)-block-poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) (PAMPS48-PEG227-PAMPS48) and poly(ethylene glycol)-block-poly(3-(methacryloylamino)propyl) trimethylammonium chloride (PEG47-PMAPTACm, m = 27,53, and 106) with different PMAPTAC chain lengths were prepared via reversible addition-fragmentation chain transfer controlled living radical polymerization using PEG-based macro chain transfer agents. The subscript numbers in abbreviation represent the degree of polymerization of the block. Mixing of aqueous solutions of the oppositely charged anionic triblock copolymer, PAMPS48-PEG227-PAMPS48 and cationic diblock copolymers, PEG47-PMAPTACm led to the spontaneous formation of Polyion Complex (PIC) micelles. The characterization data of NMR, light scattering, ζ-potential, and transmission electron microscopic measurements indicated that the PIC flower micelles were formed comprising the segregated PIC core and surrounded hydrophilic linear and loop PEG shell chains. Aggregation number and hydrodynamic radius achieved maximum values when anionic and cationic block chain lengths of the block copolymers were approximately the same.