Combined hydrophobicity and mechanical durability through surface nanoengineering.

Paul R Elliott,Thomas P Filburn,Sergei F Burlatsky,David U Furrer,Stephen P Stagon,Hanchen Huang

doi:10.1038/srep09260

Abstract

This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Specifically, the hydrophobicity derives from nanoscale features of mechanically hard ZnO nanorods and the mechanical durability derives from the composite structure of a hard ZnO nanorod core and soft polymer shell. Experimental characterization correlates the morphology of the nanoengineered surfaces with the combined hydrophobicity and mechanical durability, and reveals the responsible mechanisms. Such surfaces may find use in applications, such as boat hulls, that benefit from hydrophobicity and require mechanical durability.

Highlights

This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites
Lanthanide oxides form an intrinsically hydrophobic surface that is resistant to high temperatures and abrasive wear, but such materials are prohibitively expensive for large-scale technological applications due to the scarcity of rare earth materials[6]
While we chose zinc oxide (ZnO) nanorods fabricated using high temperature CVD as a prototype, ZnO nanorods of similar morphologies can be fabricated through low-cost, chemical vapor deposition methods, or solution-phase synthesis methods, which are advantageous for manufacturing[17,18]

Summary

Introduction

This paper reports combined hydrophobicity and mechanical durability through the nanoscale engineering of surfaces in the form of nanorod-polymer composites. Silica micro- and nano-particles in an epoxy spray coating have been used to achieve super-hydrophobicity with a low change in surface roughness after wear testing, but wetting properties after mechanical wear are not reported[8]. We design the degree of air trapping for hydrophobicity control, and further design a zinc oxide (ZnO)-polymer composite for mechanical durability. ZnO nanorods with polymer shells have been shown to be applicable in photovoltaic cells[13], and light emitting diodes[14] The coupling of these properties and mechanical toughness may be beneficial for emerging technologies. We choose polyurethane as the polymer because it is resistant to outdoor environment, has the right viscosity for desirable thickness of film and coating on the nanorods, and has a wetting angle of about 90u for both hydrophilic and hydrophobic control

Methods

Results

Conclusion