Equilibrium Dynamics of a Polymer Bicontinuous Microemulsion

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• 作者：Kristin L. Brinker ; Simon G. J. Mochrie ; Wesley R. Burghardt
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：July 10, 2007
• 年：2007
• 卷：40
• 期：14
• 页码：5150 - 5160
• 全文大小：186K
• 年卷期：v.40,no.14(July 10, 2007)
• ISSN：1520-5835

文摘

The equilibrium dynamics of a bicontinuous microemulsion composed of polystyrene, polyisoprene,and poly(styrene-block-isoprene) was characterized using rheology and X-ray photon correlation spectroscopy(XPCS). XPCS measurements, which probed dynamics at length scales comparable to the microemulsion domainsize, show stretched-exponential relaxation of the dynamic structure factor and a wavevector-dependent Onsagercoefficient. Values of the Onsager coefficient corresponding to zero wavevector (q = 0) and the peak of thestatic structure factor (q = q_max) were independently used to test rheological predictions for bicontinuousmicroemulsions developed by Pätzold and Dawson. The theory, which is based on a Landau-Ginzburg model,describes the shape of the relaxation spectrum and predicts the temperature dependence of the rheological propertiesquite well. However, for either case of the Onsager coefficient (at q = 0 and q = q_max), the theory fails to predictthe absolute values of the zero-shear viscosity and average relaxation time of the microemulsion. The results ofthis study highlight a need for the development of more sophisticated theory to describe the rheology of bicontinuousmicroemulsions.