Polysiloxane/multiwalled carbon nanotubes nanocomposites and their applications as ultrastable, healable and superhydrophobic coatings

Superhydrophobic coatings with high water contact angles, ultralow sliding angles, excellent stability and good healing capability were prepared by spray-coating the homogeneous suspensions of the fluorine-free polysiloxane/multiwalled carbon nanotubes (POS/MWCNTs) nanocomposites onto various substrates and cured for a period of time. The nanocomposites were synthesized by hydrolytic co-condensation of n-hexadecyltriethoxylsilane and tetraethoxysilane in the presence of acid activated MWCNTs. The nanocomposites composed of POS-modified MWCNTs and free POS are highly dispersible in various alkanes and arenes. The nanocomposites and their coatings were characterized using a wide range of electron microscopy and other analytical techniques. In addition, the effects of various parameters, e.g., acid activation of MWCNTs, diameter of MWCNTs, spray-coating density and annealing temperature, on superhydrophobicity and morphology of the coatings were investigated. Moreover, the stability and healing capability of the coatings were studied. The coatings show negligible change in CAs and maintain low SAs after various harsh stability tests, e.g., intensive sand abrasion from a height of 300 cm. Also, the slightly damaged coatings are healable with the help of toluene and annealing. The mechanisms for the excellent stability and good healing capability were proposed. The ultrastable, healable and superhydrophobic POS/MWCNTs coatings are very promising for various practical applications.