Effect of Surface Microstructures on Hydrophobicity and Barrier Property of Anticorrosive Coatings Prepared by Soft Lithography

Dawei Zhang,Xiaoli Chen,Haiyang Li,Hongchang Qian,Xiaogang Li

doi:10.1155/2014/342184

Abstract

Enhancing the hydrophobicity of organic coatings retards their interaction with water and often leads to better protectiveness over metal corrosion. In this study, a soft lithography method was used to prepare epoxy coatings which showed surface microstructures in high replication to sandpapers. The effect of microstructures on coating’s hydrophobicity and barrier property was investigated. Compared to flat coatings, the microstructured coatings showed much higher water contact angles, which further increased with finer sandpapers. Determined by electrochemical impedance spectroscopy (EIS), the flat coating exhibited a higher anticorrosive performance than the microstructured coatings. With the use of finer sandpaper, the groove size of the corresponding microstructured coating was reduced. And a lower anticorrosive performance was observed since more defects might be formed in a given area of coating during the imprinting process. As the groove size of the coatings was further decreased to 5.7 µm, the microstructures became too small for water to easily penetrate through. Therefore, trapped air acted as an additional barrier and contributed to an increased anticorrosive performance compared to other microstructured coatings.

Highlights

Corrosion poses significant threats to the reliability of engineering materials and structures and costs an economic loss of ∼3% GDP
Solvent-free epoxy anticorrosive coatings were prepared via a soft lithography method to obtain surface microstructures similar to sandpapers (Scheme 2)
Solvent-free epoxy coatings with sandpaper-like microstructured surfaces were prepared via a soft lithography method

Summary

Introduction

Corrosion poses significant threats to the reliability of engineering materials and structures and costs an economic loss of ∼3% GDP. Compared to flat surfaces which rarely show water contact angles (θ) above 120∘, rough surfaces can achieve higher hydrophobicity and even a superhydrophobic state with θ > 150∘ On these surfaces, the air trapped in the micro/ nanostructures forms an additional barrier against water penetration [11]. These micro/nanostructures can produce an excellent self-cleaning effect on the superhydrophobic surface, where water droplets and dissolved corrosive species can roll off [12, 13] To date, such surfaces are mostly prepared by etching or hydrothermal conversion to generate micro/nanoscale roughness, followed by grafting hydrophobic chains [14,15,16]. The hydrophobicity of the obtained coatings was compared via contact angle analysis and the effect of microstructures on barrier property of the coatings was investigated by electrochemical measurements

Materials and Methods

Results and Discussion

Conclusions