Silicone/Ag@SiO2 core-shell nanocomposite as a self-cleaning antifouling coating material.

Mohamed S Selim,Feng Q Wang,Yong Huang,Hui Yang,Nesreen A Fatthallah,Xue Li

doi:10.1039/c8ra00351c

Abstract

The effects of Ag@SiO2 core–shell nanofiller dispersion and micro-nano binary structure on the self-cleaning and fouling release (FR) in the modelled silicone nano-paints were studied. An ultrahydrophobic polydimethylsiloxane/Ag@SiO2 core–shell nanocomposite was prepared as an antifouling coating material. Ag@SiO2 core–shell nanospheres with 60 nm average size and a preferential {111} growth direction were prepared via a facile solvothermal and a modified Stöber methods with a controlled shell thickness. Ag@SiO2 core–shell nanofillers were inserted in the silicone composite surface via solution casting technique. A simple hydrosilation curing mechanism was used to cure the surface coating. Different concentrations of nanofillers were incorporated in the PDMS matrix for studying the structure–property relationship. Water contact angle (WCA) and surface free energy determinations as well as atomic force microscopy and scanning electron microscope were used to investigate the surface self-cleaning properties of the nanocomposites. Mechanical and physical properties were assessed as durability parameters. A comparable study was carried out between silicone/spherical Ag@SiO2 core–shell nanocomposites and other commercial FR coatings. Selected micro-foulants were used for biological and antifouling assessments up to 28 days. Well-distributed Ag@SiO2 core–shell (0.5 wt%) exhibited the preferable self-cleaning with WCA of 156° and surface free energy of 11.15 mN m−1.

Highlights

Biofouling on ship hulls increases drag resistance and hydrodynamic weight which result in reducing shipping velocity and increasing fuel consumption and emissions of harmful air pollutants.[1,2] Antifouling coatings based on organotin compounds pose a threat to the marine environment
Ag@SiO2 core–shell nanospheres with 60 nm average size and a preferential {111} growth direction were prepared via a facile solvothermal and a modified Stober methods with a controlled shell thickness
Well-distributed Ag@SiO2 core–shell (0.5 wt%) exhibited the preferable self-cleaning with Water contact angle (WCA) of 156 and surface free energy of 11.15 mN mÀ1

Summary

Introduction

Biofouling on ship hulls increases drag resistance and hydrodynamic weight which result in reducing shipping velocity and increasing fuel consumption and emissions of harmful air pollutants.[1,2] Antifouling coatings based on organotin compounds pose a threat to the marine environment. Alternative tin-free antifouling coatings employing copper and/or booster biocides are the principal replacement coatings but these materials are deleterious to the environment. Their toxic effects have been found to extend to non-target species with an ecological risk to 95% of organisms in the water column even at very low concentrations.[3] The substantial environmental toxicity issues and the increased global restrictions on the applications of biocidal antifouling paints have motivated. Innovation of organic/inorganic hybrid nanocomposites is a modern strategy for superior FR coating.[9,10]

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Results

Conclusion