Self-assembly of polystyrene nano particles into patterns of random-close-packed monolayers via chemically induced adsorption
Self-assembly of polystyrene nano particles into patterns of random-close-packed monolayers via chemically induced adsorption
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DOI：
10.1039/b108631f
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发表时间：
2002-01-01
影响因子：
3.3
通讯作者：
Takei, H
中科院分区：
文献类型：
--
作者：
Himmelhaus, M;Takei, H
我们已经发现，将1-乙基3-（3-（二甲氨基）丙基）碳二亚胺（EDC）添加到硫酸化聚苯乙烯（PS）纳米颗粒的悬浮液中导致在均匀的以及化学图案化的表面上形成不规则的、致密堆积的单层自组装颗粒。吸附过程敏感地依赖于EDC浓度，临界浓度为13 mM。在高于此临界值的较高浓度下，随机密堆积（RCP）单层形成，而不管基底是否为天然金、由疏水或亲水烷硫醇改性的金表面或铬/氧化铬。另一方面，在较低浓度下，仅在羧基封端的表面上观察到颗粒吸附。我们将描述如何利用这种现象来形成PS纳米颗粒的二维图案。首先，通过微接触印刷（muCP）在自然金上形成由羧基和甲基封端的硫醇组成的图案。随后将图案暴露于具有在1.3至5.2mM范围内的适当EDC浓度的硫酸化PS颗粒的悬浮液，导致图案化的rcp单层。在本文的后半部分，我们讨论了各种吸附机制的基础上观察与紫外-可见光谱和扫描电子显微镜（SEM）。提出了两种吸附机制所观察到的现象。
We have found that addition of 1-ethyl 3-(3-(dimethylamino)propyl)carbodiimide (EDC) to a suspension of sulfated polystyrene (PS) nanoparticles leads to formation of an irregular, dense-packed monolayer of self-assembled particles on homogeneous as well as chemically patterned surfaces. The adsorption process depends sensitively on the EDC concentration with a critical concentration of 13 mM. At higher concentrations above this critical value, random-close-packed (rcp) monolayers form irrespective of whether the substrate is native gold, a gold surface modified by either hydrophobic or hydrophilic alkanethiols, or chromium/chromium oxide. On the other hand, at lower concentrations particle adsorption is observed only on carboxy-terminated surfaces. We will describe how this phenomenon can be utilized to form 2-dimensional patterns of PS nanoparticles. First, a pattern consisting of carboxy and methyl-terminated thiols is formed on native gold by means of microcontact printing (muCP). Subsequent exposure of the pattern to a suspension of sulfated PS particles with an appropriate EDC concentration in the range 1.3 to 5.2 mM leads to a patterned rcp monolayer. In the second half of the paper we discuss various adsorption mechanisms based on observations with UV-vis spectroscopy and scanning electron microscopy (SEM). Two adsorption mechanisms governing the observed phenomena are proposed.