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Updated: Jan 26, 2026

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
pH-Responsive Intra- and Inter-Molecularly Micelle Formation of Anionic Diblock Copolymer in Water
Masanobu Mizusaki1, Yoshihiko Shimada2, Yotaro Morishima3
1Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan. mizusaki.masanobu@sharp.co.jp.
Abstract:
Poly(sodium2-(acrylamido)-2-methylpropanesulfonate)-block-poly(sodium11-(acrylamido)undecanoate) (PAMPS⁻PAaU) was synthesized via reversible addition-fragmentation chain transfer (RAFT)-controlled radical polymerization. The "living" polymerization of PAaU was evidenced by the fact that the molecular weight distribution was narrow (Mw/Mn = 1.23). The pH-induced association behavior of PAMPS⁻PAaU in 0.1 M NaCl aqueous solutions as a function of solution pH was investigated by ¹H NMR spin-spin relaxation time, dynamic light scattering (DLS), static light scattering (SLS), and fluorescence probe techniques. These results indicated that PAMPS⁻PAaU formed polymer micelles in 0.1 M NaCl aqueous solutions at pH < 9. At pH = 8⁻9, the polymer formed the micelles intramolecularly due to hydrophobic self-association of the PAaU block within the single polymer chain. On the other hand, at pH < 8, micellization occurred intermolecularly to form polymer micelles comprising hydrophobic PAaU cores and hydrophilic PAMPS shells.
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