Adsorptive Spin Coating To Study Thin-Film Stability in Both Wetting and Nonwetting Regimes
Adsorptive Spin Coating To Study Thin-Film Stability in Both Wetting and Nonwetting Regimes
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吸附旋涂研究润湿和非润湿状态下的薄膜稳定性
DOI：
10.1021/acs.langmuir.9b00923
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
Chen, Wei
中科院分区：
文献类型：
--
作者：
Qi, Yueyue;Nguyen, Haimi;Lim, Kelly Sin;Wang, Wenyun;Chen, Wei
研究了一种新的薄膜制备方法——吸附自旋镀膜法在硅片负载的聚二甲基硅氧烷（PDMS）衬底上制备聚乙烯醇（PVOH）薄膜。该方法利用了PVOH在短接触时间内在基液界面上的快速自发吸附和纺丝过程中干燥的方向性。与浸渍涂层的结果相似，PVOH薄膜在2 kDa的PDMS衬底上湿化，在较厚的PDMS衬底上表现出脱湿的分形形貌。该方法生成的PVOH膜的厚度与浸涂制备的膜相当，除了在较低的自旋速率下获得较厚的PVOH膜，遵循湿润状态下的Meyerhofer关系。采用高速摄影技术捕捉密闭PVOH液滴的逐步脱湿动态。干燥和聚合物聚集始于液滴的外围，并向液滴的中心扩散。每个脱湿薄膜都采用原始液滴的足迹，并显示全局有序的图案，这取决于初始液滴尺寸和自旋速率。如果PVOH薄膜是连续的，并给予足够的时间干燥，那么它们对水冲洗具有优异的稳定性。这种新的吸附自旋涂层方法不仅简单，而且具有独特的能力，能够产生全局有序的形貌，这些形貌是快速自发吸附、自旋对称和时间和空间可调节的干燥速率的结果。它是一种有价值的工具，用于制造各种表面吸附/反应迅速的薄膜系统，无论是在润湿还是非润湿状态下。
A new thin-film fabrication method, adsorptive spin coating, was evaluated in the preparation of poly(vinyl alcohol) (PVOH) thin films on silicon-wafer-supported poly(dimethylsiloxane) (PDMS) substrates. This method takes advantage of the rapid spontaneous adsorption of PVOH at the substrate–solution interface during the brief contact period and the directionality of drying during spinning. Similar to the results obtained using dip coating, the PVOH thin films wet the 2 kDa PDMS substrate and exhibit dewetted fractal morphologies on thicker PDMS substrates. This method generated PVOH films with thicknesses that were comparable to those prepared by dip coating except that thicker PVOH films were obtained at lower spin rates, following the Meyerhofer relationship in the wetting regime. Stepwise dewetting dynamics of confined PVOH drops were captured using high-speed photography. Drying and polymer aggregation initiate at the periphery of the drop and propagate toward the center of the drop. Each dewetted thin film adopts the footprint of the original drop and shows globally ordered patterns, which depend on both initial drop size and spin rate. The PVOH thin films have excellent stability toward water rinse if they are continuous and are given sufficient time to dry. This new adsorptive spin-coating method is not only straightforward but also unique in its ability to generate globally ordered morphologies that are the outcome of fast spontaneous adsorption, spin symmetry, and temporally and spatially adjustable drying rates. It is a valuable tool for fabricating a wide range of thin-film systems where surface adsorption/reaction is rapid, in both wetting and nonwetting regimes.