Memory of Surface Patterns in Mixed Polymer Brushes: Simulation and Experiment

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• 作者：Svetlana Santer ; Alexey Kopyshev ; Jö ; rn Donges ; J&uuml ; rgen R&uuml ; he ; Xueguang Jiang ; Bin Zhao ; Marcus M&uuml ; ller
• 刊名：Langmuir
• 出版年：2007
• 出版时间：January 2, 2007
• 年：2007
• 卷：23
• 期：1
• 页码：279 - 285
• 全文大小：584K
• 年卷期：v.23,no.1(January 2, 2007)
• ISSN：1520-5827

文摘

The correlation between the morphology of mixed polymer brushes and fluctuations of the grafting points isinvestigated by single-chain-in-mean-field simulations and experiments. The local topography of two types of mixedpolystyrene-polymethylmethacrylate (PS-PMMA) brushes that differ in their modes of attachment has been studiedduring repeated microphase separation into laterally structured and homogeneous morphologies upon changing solvents.In the first type of brush (conventional), each of the surface-attached initiator groups starts the growth of either a PSor a PMMA chain in a random fashion. In the second case (Y-shaped mixed brushes), two chains of different typesare attached to the same anchor group on the substrate. Whereas in the first case statistical fluctuations of the chemicalcomposition occur on a local scale, such composition fluctuations are strongly suppressed in the latter case. Themicrophase-separated morphology is similar in both cases, but Y-shaped brushes exhibit a significantly weaker domainmemory than do conventional PS-PMMA mixed brushes. The results of the experiment are compared with simulations,and a simple phenomenological argument and qualitative agreement are found. The observations demonstrate thatsmall fluctuations in the grafting points are amplified by the microphase separation and nucleate the location of thedomains in the mixed brush.