New superhydrophobic nanocomposites as anti-corrosion coating films. Part I: Synthesis and characterization of poly (styrene/vinyl acetate)-SiO2 nanocomposites as a water-repelling surface via nanoemulsion polymerization technique

Abstract

This paper aims to synthesize new robust superhydrophobic coated films to protect the carbon steel petroleum pipelines from corrosion. Three (styrene/vinyl acetate) copolymers with monomer molar ratio of (0.17:0.43), (0.17:0.22), and (0.34:0.22) denoted as C1-, C2-, and C3-copolymers, respectively, were synthesized as hydrophobic coating materials. SiO2 nanoparticles (SiO2-NPs) with an average size ranging from 91 to 98 nm were prepared via the sol-gel technique. Two functionalized SiO2-NPs using dodecyl triethoxysilane and hexadecyl trimethoxysilane as precursors were synthesized. Two composites denoted as N- and M-composites were physically fabricated by incorporating the functionalized SiO2-NPs into a C3-copolymer matrix. The chemical structures of the prepared copolymers and the purified SiO2 nanoparticles were elucidated by FT-IR and 1H NMR spectroscopies. The molecular weights of the prepared copolymers were measured using gel permeation chromatography. Thermo-gravimetric analysis (TGA) was used to investigate the thermal properties of the prepared copolymers and the composites. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques displayed the surface topography of the carbon steel surfaces coated by C3-copolymer and (N- and M-) composites. The results showed that a highly superhydrophobic (water-repellent) coating film was achieved by M-composite with a static contact angle of 162.87 ± 0.81o.