Polydimethylsiloxane (PDMS) is a widely used inexpensive, non-toxic material which has many advantages. But it is generally considered that PDMS does not adhere to the other substrates without the special treatments due to its low surface energy. However, in this paper, it is the first time that we found that the PDMS adhered on the silicon dioxide substrate to form an adhesive layer only by the routine cast molding process. The mechanism of the PDMS adhesion on the silicon dioxide substrate during the process was illustrated in detail. The smooth, thin, transparent, hydrophobic and selective PDMS adhesion layer can be used as a functional coating to improve the special performances of the micro/nano devices. Finally, as an example, a facile approach is proposed to realize the superhydrophobic surfaces by combining the SiO2 microstructure with the PDMS adhesion layer.

Reversibly switching wettability between superhydrophobicity and superhydrophilicity has attracted widespread interest because of its important applications. In this work, we propose a reversible superhydrophobic–superhydrophilic conversion induced by charge injection and heating. Different from the conventional electrowetting phenomenon caused by the accumulation of solid–liquid interfacial charges, we discovered a phenomenon where charge injection and accumulation at the solid surface results in a sharp increase in wettability. The wettability of a sprayed SiO2 nanoparticle coating on a glass slide was shown to change from superhydrophobic to superhydrophilic by charge injection and heating, and the superhydrophobicity was restored by heating, verifying a reversible superhydrophobic–superhydrophilic conversion. The influence of voltage, temperature, and time on the coating wettability and its durability under reversible conversion have been studied.

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