Solution Behavior of Double-Hydrophilic Block Copolymers in Dilute Aqueous Solution

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• 作者：Olivier Casse ; Andriy Shkilnyy ; J眉rgen Linders ; Christian Mayer ; Daniel H盲ussinger ; Antje V枚lkel ; Andreas F. Th眉nemann ; Rumiana Dimova ; Helmut C枚lfen ; Wolfgang Meier ; Helmut Schlaad ; Andreas Taubert
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：June 12, 2012
• 年：2012
• 卷：45
• 期：11
• 页码：4772-4777
• 全文大小：297K
• 年卷期：v.45,no.11(June 12, 2012)
• ISSN：1520-5835

文摘

The self-assembly of double-hydrophilic poly(ethylene oxide)鈥損oly(2-methyl-2-oxazoline) diblock copolymers in water has been studied. Isothermal titration calorimetry, small-angle X-ray scattering, and analytical ultracentrifugation suggest that only single polymer chains are present in solution. In contrast, light scattering and transmission electron microscopy detect aggregates with radii of ca. 100 nm. Pulsed field gradient NMR spectroscopy confirms the presence of aggregates, although only 2% of the polymer chains undergo aggregation. Water uptake experiments indicate differences in the hydrophilicity of the two blocks, which is believed to be the origin of the unexpected aggregation behavior (in accordance with an earlier study by Ke et al. [Macromolecules2009, 42, 5339鈥?344]). The data therefore suggest that even in double-hydrophilic block copolymers, differences in hydrophilicity are sufficient to drive polymer aggregation, a phenomenon that has largely been overlooked or ignored so far.