The Effect of a Composite Hydrophobic Coating with Zinc Oxide on the Characteristics of Polyester Matrix Composite Surfaces

In this study, a low-cost thermosetting unsaturated polyester resin (UPR) reinforced with ceramic wastes was produced and employed as a substrate, which was then coated with a hydrophobic solution comprising nano/micro scale ZnO particles. Ultra-water-repellent composite substrate surfaces were produced by a two-step process. Firstly, the composite surfaces were abraded with 600 SiC paper in order to create rough surface. In order to lower their surface energy and create unique surface topography, the textured composite substrate surfaces were next covered with a single or double layer of hydrophobic solution containing nano/micro ZnO particles. Contact angle measurements, surface free energy calculations, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrum (EDS), and optical profilometer were all used in the surface characterisation process. The highest contact angle was obtained as 157.8° when a double layer of micro ZnO-containing hydrophobic coating was applied. Surfaces coated with nano ZnO particles did not have a self-cleaning effect, whereas surfaces coated with micro ZnO additions had both superhydrophobic and self-cleaning properties. The hydrophobic coating, which contains ZnO particles of various sizes, also plays a vital role for the contact angle and specific surface energy, highlighting how crucial it is to acquire and create the right texture and surface chemistry. The synergistic effect of the processes on superhydrophobic and self-cleaning properties has been verified and discussed.