Regular Article
Robust, heat-resistant and multifunctional superhydrophobic coating of carbon microflowers with molybdenum trioxide nanoparticles

https://doi.org/10.1016/j.jcis.2017.07.091Get rights and content

Abstract

Superhydrophobic materials have triggered large interest due to their widespread applications, such as self-cleaning, corrosion resistance, anti-icing, and oil/water separation. However, suffering from weak mechanical strength, plenty of superhydrophobic materials are limited in practical application. Herein, we prepared hierarchical carbon microflowers (CMF) dispersed with molybdenum trioxide (MoO3) nanoparticles (MoO3/CMF) via a two-step preparation method. Taking advantage of high-adhesion epoxy resin and the modification with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES), the modified MoO3/CMF (PDES-MoO3/CMF) coating on various substrates shows great waterproof ability, excellent chemical stability, good mechanical durability, and self-cleaning property. More significantly, the prepared PDES-MoO3/CMF powder with high thermal stability (250 °C) can be used for oil/water separation due to its special flower-like structure and superhydrophobicity/superoleophilicity. All of these advantages endow the superhydrophobic powders with huge potential in the practical applications.

Graphical abstract

Multifunctional superhydrophobic PDES-MoO3/CMF powders created by a two-step method can be used in robust, heated-resistant superhydrophobic coating and separate oil/water mixture.

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Introduction

Superhydrophobic surface, with a water contact angle greater than 150° and a sliding angle lower than 10°, has aroused tremendous attentions because of its characteristic properties and potential commercial value [1], [2], [3], [4], [5], [6]. There are some superhydrophobic examples in nature, such as lotus leaves, water strider, and some insect wings, which have inspired people to explore superhydrophobic field [7], [8]. After abundant systematic researches, it has been demonstrated that the two key factors for formation of superhydrophobic surfaces are the micro/nano-hierarchical structures and low-surface-energy components [9], [10], [11]. In the past decades, plenty of superhydrophobic materials have been developed and applied in many fields, including waterproofing, anti-fouling, self-cleaning, anti-icing, antibacterial, corrosion resistance, energy-conversion system, water collection, patterned crystallization, and oil/water separation [12], [13], [14], [15], [16], [17], [18], [19], [20].

Up to date, with the remarkable development in material science and biomimetic studies, numerous techniques have been used to create superhydrophobic materials, including hydrothermal technique [21], etching [22], assembling [23], phase separation [24], electrodeposition [25], chemical vapor deposition (CVD) [26], and electrospinning method [27]. Among all methods, coating method is a relatively promising approach to prepare superhydrophobic surfaces because it is substrate-independent and simple. For example, Xue and co-workers used polystyrene/SiO2 core/shell nanoparticles as a coating skeleton and polydimethylsiloxane as hydrophobic interconnection to fabricate lasting superhydrophobic surfaces [28]. Li’s group prepared colored self-cleaning superhydrophobic coatings by using a facile one-step spray-coating process to coat the stearate particle suspensions on stainless steel substrates [29]. The prepared coatings maintained excellent chemical stability under harsh acidic and alkaline circumstances. Hu at el. created a superhydrophobic TiO2 film on Hastelloy substrate by dip-coating method and heat-treatment [30]. The obtained sample had water contact angle greater than 170° and excellent corrosion-resistance property. In addition to the application of solid substrates as functional or protective coatings, the superhydrophobic coating can also be used to porous soft materials for oil/water separation. Guo at el. synthesized hollow superhydrophobic SiO2 powders by typical template method and self-assembly functionalization [31]. The sponge coated with as-prepared SiO2 powders could be used to separate oil/water mixtures. Li and co-workers fabricated superhydrophobic and superoleophilic SiO2-coated polyurethane sponges for the continuous capture and removal of oils from water by a facile solution deposition process [32]. However, there are still two important factors which have not been solved perfectly: mechanical stability and thermal stability. Low adhesion strength between coating and substrates leads to the weak mechanical strength of the superhydrophobic coating [33], [34]. Moreover, the thermal stability of superhydrophobic materials is limited by its poor structural stability of low-surfaces-energy modifiers [35], [36]. Unsurprisingly, these two important factors have become the stumbling blocks to the progress of the superhydrophobic coating for a long time.

With the continual improvement of the use requirements, the superhydrophobic materials with a single property cannot satisfy the need of the practical application. Therefore, multifunctional superhydrophobic materials have sprung up and become a mainstream. Inspired by the work of Huang’s group [37], we prepared the carbon microflowers dispersed with MoO3 nanoparticles (MoO3/CMF) via a two-step preparation method. After being modified by 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (PDES), the superhydrophobic PDES-MoO3/CMF powders with high thermal stability up to 250 °C were obtained and could be used for oil/water separation. Taking advantage of high-adhesive epoxy resin, the PDES-MoO3/CMF powders can be applied to fabricate superhydrophobic coatings on varieties of substrates with excellent mechanical stability and chemical stability. For MoO3, with low electrical resistivity, high chemical stability, and a superior theoretical capacity, it has drawn particular interest as anode material used in ion batteries or organic solar cells [38], [39]. But we applied the MoO3/CMF powders to superhydrophobic materials here. Due to multiple properties of the superhydrophobic PDES-MoO3/CMF powders, it can satisfy the need of our real life and be applied to construction, transportation, and even to the military.

Section snippets

Materials

Dopamine hydrochloride (C8H11NO2·HCl) and ammonium molybdate tetrahydrate ((NH4)6Mo7O24·4H2O) were purchased from Sigma-Aldrich. Epoxy resin (E51) and curing agent were got from Beijing Yuhong Waterproof Technology Co. Ltd. Ammonia hydroxide (NH3·H2O, 28%), anhydrous ethanol, n-hexane, 1,2-dichloroethane, sulfuric acid (H2SO4), and sodium hydroxide (NaOH) were purchased from Sinopharm Chemical Reagent Co., Ltd., China. PDES was purchased from Sigma-Aldrich. In addition, all other chemicals were

Structure and characterization of MoO3/CMF powders

The structure and morphology of CMS and MoO3/CMF powders were investigated by SEM and TEM. As shown in Fig. 2a-c, the smooth CMS particles exist without micro/nano-hierarchical structures on their surfaces because of the absence of (NH4)6Mo7O24·4H2O during synthesis process. In order to prepare the MoO3/CMF powders, the dopamine was chosen as the carbon precursor because it can spontaneously self-polymerize under weak alkaline conditions and form self-supported structures. It also has a great

Conclusions

In summary, we have successfully prepared superhydrophobic hierarchical carbon microflowers dispersed with MoO3 nanoparticles (PDES-MoO3/CMF). The MoO3 originally used in battery anode has been innovatively applied to the superhydrophobic materials to change the surface morphologies and properties of PDES-MoO3/CMF. With the aid of the high-adhesion epoxy resin, these superhydrophobic particles can be applied to various substrates. And the prepared PDES-MoO3/CMF-based coatings show excellent

Acknowledgements

This work is supported by the National Natural Science Foundation of China (NO. 51605254, 51675513 and 517300059).

References (43)

  • N. Yang et al.

    One step phase separation process to fabricate superhydrophobic PVC films and its corrosion prevention for AZ91D magnesium alloy

    Mater. Sci. Eng. B

    (2016)
  • N. Xu et al.

    Corrosion performance of superhydrophobic nickel stearate/nickel hydroxide thin films on aluminum alloy by a simple one-step electrodeposition process

    Surf. Coat. Technol.

    (2016)
  • Z.J. Liu et al.

    Superhydrophobic poly(vinylidene fluoride) membranes with controllable structure and tunable wettability prepared by one-step electrospinning

    Polymer

    (2016)
  • Y.W. Hu et al.

    A corrosion-resistance superhydrophobic TiO2 film

    Appl. Surf. Sci.

    (2012)
  • F. Guo et al.

    Multifunctional hollow superhydrophobic SiO2 microspheres with robust and self-cleaning and separation of oil/water emulsions properties

    J. Colloid Interface Sci.

    (2017)
  • Y.F. Zhang et al.

    Spray-coating of superhydrophobic aluminum alloys with enhanced mechanical robustness

    J. Colloid Interface Sci.

    (2014)
  • M.F. Hassan et al.

    Carbon-coated MoO3 nanobelts as anode materials for lithium-ion batteries

    J. Power Sources

    (2010)
  • W.H. Huang et al.

    Robust superhydrophobic transparent coatings fabricated by a low-temperature sol–gel process

    Appl. Surf. Sci.

    (2014)
  • Y.F. Si et al.

    Superhydrophobic nanocoatings from materials to fabrications and to applications

    Nanoscale

    (2015)
  • Q.Y. Wen et al.

    Recent advances in the fabrication of superhydrophobic surfaces

    Chem. Lett.

    (2016)
  • B. Su et al.

    Bio-inspired interfaces with super-wettability from materials to chemistry

    J. Am. Chem. Soc.

    (2016)
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