Preparation and characterization of polyion complex micelles with phosphobetaine shells.

A pair of oppositely charged diblock copolymers, poly(2-(methacryloyloxy)ethyl phosphorylcholine)-block-poly((3-(methacryloylamino)propyl)trimethylammonium chloride) (PMPC-b-PMAPTAC) and poly(2-(methacryloyloxy)ethyl phosphorylcholine)-block-poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) (PMPC-b-PAMPS), was prepared via reversible addition–fragmentation chain transfer radical polymerization using a PMPC-based macro chain transfer agent. The pendant phosphorylcholine group in the hydrophilic PMPC block has anionic phosphate and cationic quaternary amino groups, which are neutralized within the pendant group. Therefore, the mixing of aqueous solutions of PMPC-b-PMAPTAC and PMPC-b-PAMPS leads to the spontaneous formation of simple core–shell spherical polyion complex (PIC) micelles comprising of a segregated PIC core and PMPC shells. The PIC micelles were characterized using 1H NMR spin–spin (T2) and spin–lattice relaxation times (T1), diffusion-ordered NMR spectroscopy, static light scattering, dynami...