Preparation of Water-Soluble Polyion Complex (PIC) Micelles with Random Copolymers Containing Pendant Quaternary Ammonium and Sulfonate Groups

Cationicrandom copolymers (PCm) consisting of2-(methacryloyloxy)ethyl phosphorylcholine (MPC; P) with methacroylcholinechloride (MCC; C) and anionic random copolymers (PSn) consisting of MPC and potassium 3-(methacryloyloxy)propanesulfonate(MPS; S) were prepared via a reversible addition-fragmentationchain transfer method. "m" and "n" represent the compositions (mol %) of the MCCand MPS units in the copolymers, respectively. The degrees of polymerizationfor the copolymers were 93-99. Water-soluble MPC unit containsa pendant zwitterionic phosphorylcholine group whose charges are neutralizedin pendant groups. MCC and MPS units contain the cationic quaternaryammonium and anionic sulfonate groups, respectively. The stoichiometricallycharge-neutralized mixture of a matched pair of PCm and PSn aqueous solutions resulted in the spontaneousformation of water-soluble PCm/PSn polyion complex (PIC) micelles. These PIC micelles have the MPC-richsurface and MCC/MPS core. These PIC micelles were characterized using H-1 NMR, dynamic and static light scattering, and transmissionelectron microscopic measurements. The hydrodynamic radius of thesePIC micelles depends on the mixing ratio of the oppositely chargedrandom copolymers. The charge-neutralized mixture formed maximum-sizePIC micelles.