Long-Term Reduction in Poly(dimethylsiloxane) Surface Hydrophobicity via Cold-Plasma Treatments
Long-Term Reduction in Poly(dimethylsiloxane) Surface Hydrophobicity via Cold-Plasma Treatments
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DOI：
10.1021/la403077q
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发表时间：
2013-10-22
期刊：
影响因子：
3.9
通讯作者：
Lagally, M. G.
中科院分区：
文献类型：
--
作者：
Larson, B. J.;Gillmor, S. D.;Lagally, M. G.
聚（二甲基硅氧烷），PDMS，一种多功能弹性体，是微流体系统的首选聚合物。它价格便宜，相对容易图案化，并且可渗透氧气。未改性的PDMS是高度疏水的。它通常暴露于氧等离子体以降低这种疏水性。不幸的是，PDMS表面很快就恢复到其原始的疏水状态。我们提出了两种替代的等离子体处理，产生长期的PDMS表面的润湿性能的修改。氧等离子体预处理，然后暴露于SiCl 4等离子体和氧-CCl 4混合物等离子体都导致PDMS表面的疏水性永久降低。我们用X射线光电子能谱（XPS）和接触角测量研究了等离子体处理表面的性质。我们建议，等离子体处理的PDMS表面是一个动态的马赛克的高和低接触角的功能。SiCl 4和CCl 4等离子体附着极性基团，这些极性基团阻止PDMS中存在的低分子量基团覆盖表面。我们描述了一个应用程序，受益于这些新的等离子体处理，使用PDMS模板形成密集的DNA阵列的表面上。
Poly(dimethylsiloxane), PDMS, a versatile elastomer, is the polymer of choice for microfluidic systems. It is inexpensive, relatively easy to pattern, and permeable to oxygen. Unmodified PDMS is highly hydrophobic. It is typically exposed to an oxygen plasma to reduce this hydrophobicity. Unfortunately, the PDMS surface soon returns to its original hydrophobic state. We present two alternative plasma treatments that yield long-term modification of the wetting properties of a PDMS surface. An oxygen plasma pretreatment followed by exposure to a SiCl4 plasma and an oxygen-CCl4 mixture plasma both cause a permanent reduction in the hydrophobicity of the PDMS surface. We investigate the properties of the plasma-treated surfaces with X-ray photoelectron spectroscopy (XPS) and contact angle measurements. We propose that the plasma treated PDMS surface is a dynamic mosaic of high- and low-contact-angle functionalities. The SiCl4 and CCl4 plasmas attach polar groups that block coverage of the surface by low-molecular-weight groups that exist in PDMS. We describe an application that benefits from these new plasma treatments, the use of a PDMS stencil to form dense arrays of DNA on a surface.