Mechanochemical Degrafting of a Surface-Tethered Poly(acrylic acid) Brush Promoted Etching of Its Underlying Silicon Substrate
Mechanochemical Degrafting of a Surface-Tethered Poly(acrylic acid) Brush Promoted Etching of Its Underlying Silicon Substrate
复制标题
表面系留的聚丙烯酸刷的机械化学去接枝促进了其下面的硅基板的蚀刻
DOI：
10.1021/acs.langmuir.9b02610
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
Genzer Jan
中科院分区：
文献类型：
--
作者：
Li Yuanchao;Lin Yiliang;Dai Yunkai;Ko Yeongun;Genzer Jan
在过去的几年里，人们对表面系固聚电解质电刷的稳定性进行了研究。我们以前报道过在平板硅衬底上脱接聚丙烯酸（PAA）聚合物刷。在0.1 M乙醇胺缓冲液（pH 9.0）中，研究了NaCl浓度、接枝密度和分子量对PAA毛刷稳定性的影响。缓冲溶液中没有NaCl， PAA毛刷保持完整。NaCl的加入加速了顶部二氧化硅层的溶解，促进了PAA链的脱接枝，从而有利于衬底的蚀刻。PAA接枝密度和分子量通过影响蚀刻剂的穿透势垒和局部浓度，在衬底蚀刻中起重要作用。我们还测试了锚定在硅衬底上的疏水性烷基三氯硅烷自组装单层（sam）的稳定性。结果表明，与厚的聚甲基丙烯酸甲酯刷相比，SAMs太薄，无法保护基底免受蚀刻。我们的研究结果表明，聚合物刷（特别是聚电解质刷）和锚定在硅衬底上的sam在基本环境中可能会在衬底上受到侵蚀/蚀刻，从而损害其稳定性，从而危及其在涂层、生物传感等领域的应用。
The stability of surface-tethered polyelectrolyte brushes has been investigated during the past few years. We have previously reported on the degrafting of poly(acrylic acid) (PAA) polymer brushes from flat silicon substrates. Here, we present a detailed study on the effects of NaCl concentration and the grafting density and molecular weight on the stability of PAA brushes during incubation in 0.1 M ethanolamine buffer (pH 9.0) solutions. Without NaCl in the buffer solution, the PAA brushes remain intact. Adding NaCl facilitates etching of the substrate due to accelerating dissolution of the top silica layer and promoting degrafting of the PAA chains. The PAA grafting density and molecular weight play an important role in the substrate etching by affecting the penetration barrier and local concentration of the etchants. We also tested the stability of self-assembled monolayers (SAMs) made of hydrophobic alkyltrichlorosilanes anchored on silicon substrates. The results demonstrated that the SAMs were too thin to protect the substrates from etching, in contrast to thick poly(methyl methacrylate) brushes. Our findings suggest that both polymer brushes (especially polyelectrolyte brushes) and SAMs anchored to silicon substrates may undergo erosion/etching on the substrates in basic environments, which compromises their stability and therefore jeopardizes their applications in coating, biosensing, and so forth.