Li Yuanchao, Lin Yiliang, Ko Yeongun, Kiserow Douglas, Genzer Jan
Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China.
Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, United States.
ACS Macro Lett. 2018 Jun 19;7(6):609-613. doi: 10.1021/acsmacrolett.8b00241. Epub 2018 May 14.
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.
我们通过监测硅基底局部蚀刻的变化，报告了在碱性水性缓冲液中，纳米到微米长度尺度下表面 tethered 聚（丙烯酸）（PAA）刷的机械化学辅助脱接枝的可视化。PAA 刷通过表面引发的原子转移自由基聚合制备，并在含有 0.5 M NaCl 的 0.1 M 乙醇胺缓冲液（pH 9.0）中孵育。通过扫描电子显微镜和原子力显微镜监测下层基底的形态变化。规则形状凹坑的出现表明基底被蚀刻，并且它们的数量和尺寸随着孵育时间的增加而增加。我们比较了接枝在硅基底上的 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 刷的基底保持完整。在 PAA 刷系统中，我们检测到形成了一些大凹坑，其尺寸随时间增长。PPEGMA 刷的基底上出现了许多凹坑，但与 PAA 相比尺寸要小得多。我们的研究结果表明，在给定的孵育条件下，接枝聚合物的疏水性和稳定性在下层硅基底的形态变化中起着重要作用。
