Synthesis of miktoarm star amphiphilic block copolymers via combination of NMRP and ATRP and investigation on self‐assembly behaviors |
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| Authors: | Weidong Zhang Wei Zhang Nianchen Zhou Jian Zhu Zhenping Cheng Xiulin Zhu |
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| Institution: | Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China |
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| Abstract: | The novel trifunctional initiator, 1‐(4‐methyleneoxy‐2,2,6,6‐tetramethylpip‐eridinoxyl)‐3,5‐bi(bromomethyl)‐2,4,6‐trimethylbenzene (TEMPO‐2Br), was successfully synthesized and used to prepare the miktoarm star amphiphilic poly(styrene)‐(poly(N‐isopropylacrylamide))2 (PS(PNIPAAM)2) via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMRP) techniques. Furthermore, the star amphiphilic block copolymer, poly (styrene)‐(poly(N‐isopropylacrylamide‐b‐4‐vinylpyridine))2 (PS(PNIPAAM‐b‐P4VP)2), was also prepared using PS(PNIPAAM)2 as the macroinitiator and 4‐vinylpyridine as the second monomer by ATRP method. The obtained polymers were well‐defined with narrow molecular weight distributions (Mw/Mn ≤ 1.29). Meanwhile, the self‐assembly behaviors of the miktoarm amphiphilic block copolymers, PS(PNIPAAM)2 and PS(PNIPAAM‐b‐P4VP)2, were also investigated. Interestingly, the aggregate morphology changed from sphere‐shaped micelles (4.7 < pH < 3.0) to a mixture of spheres and rods (1.0 < pH < 3.0), and rod‐shaped nanorods formed when pH value was below 1.0. The LCST of PS(PNIPAAM)2 (pH = 7) was about 31 °C and the LCST of PS(PNIPAAM‐b‐P4VP)2 was about 35 °C (pH = 3). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6304–6315, 2009 |
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| Keywords: | atom transfer radical polymerization (ATRP) living polymerization miktoarm amphiphilic copolymer nitroxide‐mediated radical polymerization self‐assembly |
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