Robust Superhydrophobic Graphene-Based Composite Coatings with Self-Cleaning and Corrosion Barrier Properties

Superhydrophobic surfaces for self-cleaning
applications often suffer from mechanical instability and do not function
well after abrasion/scratching. To address this problem, we present
a method to prepare graphene-based superhydrophobic composite coatings
with robust mechanical strength, self-cleaning, and barrier properties.
A suspension has been formulated that contains a mixture of reduced
graphene oxide (rGO) and diatomaceous earth (DE) modified with polydimethylsiloxane
(PDMS) that can be applied on any surface using common coating methods
such as spraying, brush painting, and dip coating. Inclusion of TiO2 nanoparticles to the formulation shows further increase in
water contact angle (WCA) from 159 ± 2° to 170 ± 2°
due to the structural improvement with hierarchical surface roughness.
Mechanical stability and durability of the coatings has been achieved
by using a commercial adhesive to bond the superhydrophobic “paint”
to various substrates. Excellent retention of superhydrophobicity
was observed even after sandpaper abrasion and crosscut scratching.
A potentiodynamic polarization study revealed excellent corrosion
resistance (96.78%) properties, and an acid was used to provide further
insight into coating barrier properties. The ease of application and
remarkable properties of this graphene-based composite coating show
considerable potential for broad application as a self-cleaning and
protective layer.