Sphere-to-Wormlike Network Transition of Block Copolymer Micelles Containing CdSe Quantum Dots in the Corona

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• 作者：Meng Zhang ; Mingfeng Wang ; Shu He ; Jieshu Qian ; Amir Saffari ; Anna Lee ; Sandeep Kumar ; Yasser Hassan ; Axel Guenther ; Gregory Scholes ; Mitchell A. Winnik
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：June 8, 2010
• 年：2010
• 卷：43
• 期：11
• 页码：5066-5074
• 全文大小：1023K
• 年卷期：v.43,no.11(June 8, 2010)
• ISSN：1520-5835

文摘

Poly(styrene-b-4-vinylpyridine) (PS₄₀₄-b-P4VP₇₆, where the subscripts refer to the number-averaged degree of polymerization) forms spherical crew-cut micelles with a PS core and a P4VP corona when 2-propanol is added to a solution of the polymer in chloroform. When the CHCl₃ solution also contains CdSe quantum dots, hybrid micelles form with the QDs bound to the corona. Here we report that vigorous magnetic stirring of a solution of these hybrid micelles in a solution containing 73 vol % 2-propanol leads to a morphology transformation to form three-dimensional wormlike networks that have structural features similar to that first reported by Jain and Bates [Science 2003, 300, 460−464] for a poly(butadiene-b-ethylene oxide) block copolymer in water. Under the influence of shear, PS₄₀₄-b-P4VP₇₆ micelles appear to aggregate and then rearrange to form colloidally stable networks consisting of wormlike micelles, uniform in width, that are present as loops and tails connected by T- and Y-junctions. The wormlike micelles are similar in width to the original hybrid micelles, whereas the tails of the micelles have thicker bulbous end-caps. This morphology transition is extremely sensitive to solvent composition and is also affected by the stirring rate.