Wetting Dynamics on Superhydrophilic Surfaces Prepared by Photonic Microfolding
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- 作者：Thomas Bahners ; Lutz Prager ; Jochen S. Gutmann
- 刊名：Langmuir
- 出版年：2014
- 出版时间：March 25, 2014
- 年：2014
- 卷：30
- 期：11
- 页码：3127-3131
- 全文大小：254K
- 年卷期：v.30,no.11(March 25, 2014)
- ISSN：1520-5827
文摘
The wetting dynamic on microrough and perfectly wetting (superhydrophilic) acrylates was studied. These surfaces were achieved by coating polymer films made of poly(ethyleneterephthalate) (PET) with a hydrophilic acrylate based on hydroxypropylacrylate and polyethyleneglycolmonoacrylate, which was then cured and microroughened by photonic microfolding. The high transparency of the thin acrylate layers and polymer films allowed us to record the spreading of an applied water droplet through the film samples. Subsequently, the dynamic radius of the spreading pattern rc(t) was determined from the video recording. Various models for the wetting dynamics of superhydrophilic surfaces, namely, Tanner鈥檚 law and a roughness-modified derivation published by McHale et al. in 2009, were then compared to the experimental results. Basically, the development of rc(t) in time was found to be in good agreement with McHale鈥檚 model. Data analysis showed, however, that the initial phase of the spreading, that is, for t < 1 s, was not predicted well. This differing behavior relates well to a theory published by Cazabat and Cohen Stuart, who proposed that, on rough surfaces, spreading follows a power law in three time regimes. In this model, the (very) initial spreading is expected to be similar to the spreading on a smooth surface.