Fabrication of superhydrophobic coating via a facile and versatile method based on nanoparticle aggregates

Herein, we report a facile and low cost method for the fabrication of superhydrophobic surface via spin coating the mixture of polydimethylsiloxane precursor (PDMS) and silicon dioxide (SiO2) nanoparticles. The surface hydrophobicity can be well tuned by adjusting the weight percent of PDMS and SiO2. The water contact angle (WCA) can increase from 106.8 ± 1.2° on PDMS film to 165.2 ± 2.3° on PDMS/SiO2 coating, companying with a change from adhering to rolling which was observed from tilting angle (TA) characterization. Multi-scale physical structures with SiO2 nanoparticle aggregates and networks of SiO2 nanoparticle aggregates are characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM), and they can be observed more clearly from the AFM images treated with software (WSxM). Then the relationship between surface hydrophobicity and structures is further discussed based on Wenzel and Cassie models, indicating that the appearance of networks of nanoparticle aggregates is important in the Cassie state. The superhydrophobic coating can keep the superhydrophobicity at least for one month under environment conditions and readily regenerate after mechanical damage. Additionally, the superhydrophobic coating can be fabricated using other methods including dip coating, spray coating and casting. Thus, a large area of superhydrophobic coatings can be easily fabricated. Therefore the range of possible applications for these facile and versatile methods can be expanded to various actual conditions.

The multi-scale structures and formed networks of SiO2 nanoparticle aggregates can be observed clearly by SEM and treated AFM images. The large area superhydrophobicity is readily regenerated after mechanical damage.Highlight► A facile and versatile method is provided to fabricate superhydrophobic coating. ► Multi-scale structures and the networks of nanoparticle aggregates are shown more clearly with treated AFM images. ► The networks of nanoparticle aggregates are equally important for surface superhydrophobicity with multi-scale structures. ► The large area superhydrophobic surface is long-term stable and readily regenerated after mechanical damage. ► The provided method is facile and versatile enough to be expanded to other approaches to obtain superhydrophobicity.