title: Preparation and characterization of polyion complex micelles with phosphobetaine shells.
abstract: 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 (1)H NMR spin-spin (T2) and spin-lattice relaxation times (T1), diffusion-ordered NMR spectroscopy, static light scattering, dynamic light scattering (DLS), and transmission electron microscopy techniques. The hydrodynamic size of the PIC micelle depended on the mixing ratio of PMPC-b-PMAPTAC and PMPC-b-PAMPS; the maximum size occurred at the mixing ratio yielding stoichiometric charge neutralization. The PIC micelles disintegrated to become unimers with the addition of salts.
authors.affiliation: Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo , 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Nakai
authors.forename: Midori
authors.initials: M
authors.lastname: Nishiuchi
authors.forename: Masamichi
authors.initials: M
authors.lastname: Inoue
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sanada
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakurai
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yusa
mesh_terms: D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry*; D007477:Ions / Q000138:chemical synthesis / Q000737:chemistry; D008823:Micelles; D008958:Models, Molecular; D015394:Molecular Structure; D010316:Particle Size; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D007477:Ions; D008823:Micelles; D011108:Polymers; D010767:Phosphorylcholine; D001622:Betaine