Superhydrophobic coating of silicone/β–MnO2 nanorod composite for marine antifouling

Abstract

A novel superhydrophobic series of silicone/β–MnO2 nanorod composite was successfully fabricated for marine fouling release (FR) coatings. We studied how the self-cleaning and antifouling features were affected by controlling the β–MnO2 nanorod preparation and distribution in the silicone matrix. The nanorods exhibited a single crystal structure, a mean diameter of 20–30 nm and a length of 0.5–1 μm, and they had a wurtzite structure that preferentially grew in the [100] direction which has the most stable surface, high antimicrobial, and low free energy. Nanorod fillers of different concentrations were distributed in the silicone matrix for enhancing the surface roughness, water repellency and FR features. Surface characteristics were evaluated by using the contact angle of water experiments, atomic force microscope and scanning electron microscope for studying the superhydrophobicity and antifouling attributes. Well-dispersed nanorods exhibited a particular increase in the coating roughness, superhydrophobicity, and low surface energy properties. Thermal and mechanical properties, as well as stability in different pH solutions, were tested as durability parameters. For assessing the biological and fouling repellency effects of the coating systems, chosen micro-fouling organisms were used in the laboratory for one month. Also, a field experiment was carried out by immersing the coated samples in natural seawater up to 90 days and the screening method and image analysis were used to test the FR behavior. The well-dispersed nanorods (0.5 wt.%) presented the most profound superhydrophobic FR nanostructured coating; which demonstrated a 158° and 12.65 mN/m for the surface contact angle and free energy.