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Visualization of Mechanochemically-Assisted Degrafting of Surface-Tethered Poly(Acrylic Acid) Brushes
ACS Macro Letters ( IF 5.1 ) Pub Date : 2018-05-14 00:00:00 , DOI: 10.1021/acsmacrolett.8b00241
Yuanchao Li 1, 2 , Yiliang Lin 2 , Yeongun Ko 2 , Douglas Kiserow 3 , Jan Genzer 2
Affiliation  

We report visualization of mechanochemically assisted degrafting of surface-tethered poly(acrylic acid) (PAA) brushes in a basic aqueous buffer at nanometer to micrometer length scale by monitoring changes in local etching of silicon substrates. PAA brushes were prepared by surface-initiated atom transfer radical polymerization and incubated in 0.1 M ethanolamine buffer (pH 9.0) with 0.5 M NaCl. Morphological changes of the underlying substrates were monitored by scanning electron microscopy and atomic force microscopy. The appearance of regular-shaped pits indicated etching of the substrate, and both their number and size grew with increasing incubation time. We compared the etching behaviors for PAA, poly(methyl methacrylate) (PMMA), and poly(poly(ethylene glycol) methacrylate) (PPEGMA) brushes grafted on silicon substrates. After incubation for 7 days, the substrate of PMMA brush remained intact. In PAA brush systems, we detected the formation of a few large pits whose size grew in time. Many pits showed up on the substrate of PPEGMA brush but with substantially smaller size compared to PAA. Our findings suggest that hydrophobicity and stability of the grafted polymers play an important role in the morphological changes of the underlying silicon substrates under given incubation conditions.

中文翻译:

表面束缚聚(丙烯酸)刷的机械化学辅助脱枝的可视化

我们报告通过监测硅基板局部蚀刻的变化,在纳米到微米长度尺度的基本水性缓冲液中对表面拴聚丙烯酸 (PAA) 刷进行机械化学辅助脱枝的可视化。PAA 刷通过表面引发的原子转移自由基聚合制备,并在 0.1 M 乙醇胺缓冲液 (pH 9.0) 和 0.5 M NaCl 中孵育。通过扫描电子显微镜和原子力显微镜监测底层基板的形态变化。规则形状的凹坑的出现表明基板的蚀刻,并且它们的数量和大小都随着孵育时间的增加而增加。我们比较了接枝在硅基板上的 PAA、聚(甲基丙烯酸甲酯)(PMMA)和聚(聚(乙二醇)甲基丙烯酸酯)(PPEGMA)刷的蚀刻行为。孵育 7 天后,PMMA 刷的底物保持完整。在 PAA 刷系统中,我们检测到一些大坑的形成,这些坑的大小随着时间的推移而增长。PPEGMA 刷的基材上出现了许多凹坑,但与 PAA 相比,其尺寸要小得多。我们的研究结果表明,接枝聚合物的疏水性和稳定性在给定孵育条件下对底层硅基板的形态变化起重要作用。
更新日期:2018-05-14
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