We report a simple, inexpensive and rapid method for fabrication of a stable and transparent superhydrophobic (TSHB) surface and its reversible transition to a transparent superhydrophilic (TSHL) surface. We provide a mechanistic understanding of the superhydrophobicity and superhydrophilicity and the reversible transition. The proposed TSHB surface was created by candle sooting a partially cured n-hexane + PDMS surface followed by washing with DI water. The nano/microscopic grooved structures created on the surface conforms Cassie - Baxter state and thus gives rise to superhydrophobicity (water contact angle (WCA) = 161° ± 1°). The TSHB surface when subjected to oxygen plasma develops -OH bonds on the surface thus gets transformed into a TSHL surface (WCA < 1°). Both surface chemistry and surface morphology play important roles for the superhydrophobic to superhydrophilic transition. In the Cassie - Baxter relation for a composite surface, due to the capillary spreading of liquid in the nano/micro grooves, both θ₁, θ₂ = 0, thus giving rise to complete wetting. Rapid recovery of superhydrophobicity from superhydrophilicity was achieved by heating the TSHL surface at 150 °C for 30 min, due to a much faster adsorption of the -OH bonds into the PDMS. Thus it is possible to achieve reversible transition from TSHB to TSHL and vice versa by exposing to oxygen plasma and heat, respectively.

中文翻译：

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透明可逆超疏水-超亲水表面的简便制造和机械理解。

我们报告了一种简单，便宜且快速的方法，用于制造稳定且透明的超疏水性（TSHB）表面及其可逆转变为透明的超亲水性（TSHL）表面。我们提供了对超疏水性和超亲水性以及可逆转变的机械理解。提出的TSHB表面是通过将部分固化的正己烷+ PDMS表面用蜡烛吹灰，然后用去离子水洗涤来创建的。在表面上形成的纳米/微观沟槽结构符合Cassie-Baxter状态，因此会产生超疏水性（水接触角（WCA）= 161°±1°）。TSHB表面在经受氧等离子体作用时会在表面上形成-OH键，从而转变为TSHL表面（WCA <1°）。表面化学和表面形态对于超疏水至超亲水转变都起着重要作用。在复合表面的Cassie-Baxter关系中，由于液体在纳米/微沟槽中的毛细管扩散，两个θ₁，θ ₂  = 0，从而引起完全润湿。通过将TSHL表面在150°C下加热30分钟，可以从超亲水性中快速恢复超疏水性，这是因为-OH键在PDMS中的吸收要快得多。因此，通过分别暴露于氧等离子体和热量下，可以实现从TSHB到TSHL的可逆转变，反之亦然。