title: Formation of Polyion Complex (PIC) Micelles and Vesicles with Anionic pH-Responsive Unimer Micelles and Cationic Diblock Copolymers in Water.
abstract: A random copolymer (p(A/MaU)) of sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS) and sodium 11-methacrylamidoundecanate (MaU) was prepared via conventional radical polymerization, which formed a unimer micelle under acidic conditions due to intramolecular hydrophobic interactions between the pendant undecanoic acid groups. Under basic conditions, unimer micelles were opened up to an expanded chain conformation by electrostatic repulsion between the pendant sulfonate and undecanoate anions. A cationic diblock copolymer (P163M99) consisting of poly(3-(methacrylamido)propyl)trimethylammonium chloride (PMAPTAC) and hydrophilic polybetaine, 2-(methacryloyloxy)ethylphosphorylcholine (MPC), blocks was prepared via controlled radical polymerization. Mixing of p(A/MaU) and P163M99 in 0.1 M aqueous NaCl under acidic conditions resulted in the formation of spherical polyion complex (PIC) micelles and vesicles, depending on polymer concentration before mixing. Shapes of the PIC micelles and vesicles changed under basic conditions due to collapse of the charge balance between p(A/MaU) and P163M99. The PIC vesicles can incorporate nonionic hydrophilic guest molecules, and the PIC micelles and vesicles can accept hydrophobic guest molecules in the hydrophobic core formed from p(A/MaU).
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo , 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Ohno
authors.affiliation: Department of Materials Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ishihara
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo , 2167 Shosha, Himeji, Hyogo 671-2280, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Yusa