Synthesis of double-hydrophilic poly(methylacrylic acid)-poly(ethylene glycol)-poly(methylacrylic acid) triblock copolymers and their micelle formation

• Published in: Polymer international 2011-02, Vol.60 (2), p.327-332
• Main Authors: Liu, Ren, Tao, Youhua, Zhu, Ye, Chen, Mingqing, Yang, Cheng, Liu, Xiaoya
• Format: Article
• Language: English
• Subjects: Applied sciences; Block copolymers; double-hydrophilic; Exact sciences and technology; Fluid dynamics; Fluid flow; Lasers; Micelles; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; Radicals; reversible-deactivation radical polymerization; Self assembly; triblock copolymers
• ISSN: 0959-8103; 1097-0126; 1097-0126
• DOI: 10.1002/pi.2953

The aim of the work reported was to synthesize a series of double‐hydrophilic poly(methacrylic acid)‐block‐poly(ethylene glycol)‐block‐poly(methacrylic acid) (PMAA‐b‐PEG‐b‐PMAA) triblock copolymers and to study their self‐assembly behavior. These copolymeric self‐assembly systems are expected to be potential candidates for applications as carriers of hydrophilic drugs. Bromo‐terminated difunctional PEG macroinitiators were used to synthesize well‐defined triblock copolymers of poly(tert‐butyl methacrylate)‐block‐poly(ethylene glycol)‐block‐poly(tert‐butyl methacrylate) via reversible‐deactivation radical polymerization. After the removal of the tert‐butyl group by hydrolysis, double‐hydrophilic PMAA‐b‐PEG‐b‐PMAA triblock copolymers were obtained. pH‐sensitive spherical micelles with a core–corona structure were fabricated by self‐assembly of the double‐hydrophilic PMAA‐b‐PEG‐b‐PMAA triblock copolymers at lower solution pH. Transmission electron microscopy and laser light scattering studies showed the micelles were of nanometric scale with narrow size distribution. Solution pH and micelle concentration strongly influenced the hydrodynamic radius of the spherical micelles (48–310 nm). A possible reason for the formation of the micelles is proposed. Copyright © 2010 Society of Chemical Industry Double‐hydrophilic poly(methacrylic acid)‐block‐poly(ethylene glycol)‐block ‐poly(methacrylic acid) (PMAA‐b‐PEG‐b‐PMAA) triblock copolymers were synthesized via reversible‐deactivation radical polymerization, and subsequent removal of the tert‐butyl group by hydrolysis. The spherical micelles formed by the PMAA‐b‐PEG‐b‐PMAA copolymers at lower pH were of nanometric size with a narrow size distribution. Solution pH and micelle concentration strongly influenced the hydrodynamic radius of the micelles.