Structure of Polymer Layers Grafted to Nanoparticles in Silica鈥揚olystyrene Nanocomposites

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• 作者：Georgios G. Vogiatzis ; Doros N. Theodorou
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：June 11, 2013
• 年：2013
• 卷：46
• 期：11
• 页码：4670-4683
• 全文大小：726K
• 年卷期：v.46,no.11(June 11, 2013)
• ISSN：1520-5835

文摘

The structural features of polystyrene brushes grafted on spherical silica nanoparticles immersed in polystyrene are investigated by means of a Monte Carlo methodology based on polymer mean field theory. The nanoparticle radii (either 8 or 13 nm) are held constant, while the grafting density and the lengths of grafted and matrix chains are varied systematically in a series of simulations. The primary objective of this work is to simulate realistic nanocomposite systems of specific chemistry at experimentally accessible length scales and study the structure and scaling of the grafted brush. The profiles of polymer density around the particles are examined; based on them, the brush thickness of grafted chains is estimated and its scaling behavior is compared against theoretical models and experimental findings. Then, neutron scattering spectra are predicted both from single grafted chains and from the entire grafted corona. It is found that increasing both the grafting density and the grafted chain molar mass drastically alters the brush dimensions, affecting the wetting behavior of the polymeric brush. On the contrary, especially for particles dispersed in high molecular weight matrix, variation of the matrix chain length causes an almost imperceptible change of the density around the particle surface.