Elsevier

Applied Surface Science

Volume 256, Issue 12, 1 April 2010, Pages 3972-3976
Applied Surface Science

Preparation of lotus-like superhydrophobic fluoropolymer films

https://doi.org/10.1016/j.apsusc.2010.01.059Get rights and content

Abstract

Styrene and 2,2,3,4,4,4-hexafluorobutyl methacrylate copolymers were synthesized by bulk polymerization, and the superhydrophobic copolymer films were prepared subsequently using phase separation technique. The copolymer was dissolved in tetrahydrofuran, and then added ethanol into the solution thereafter, to induce phase separation. The microstructures of the polymer films were controlled by the degree of phase separation, which was enhanced properly by the concentration of ethanol. The surface morphology of the films, observed by environmental scanning electron microscope, is similar to that of the lotus leaf. The contact angle and sliding angle were measured as 154.3° and 5.8°, respectively. The excellent superhydrophobic property demonstrated that the phase separation technique is useful for preparing lotus-like fluoropolymer films.

Introduction

The wetting behavior of solid surface is governed by both surface roughness and chemical composition. Consequently, increasing surface roughness and lowering surface tension can dramatically enhance surface water repellency [1], [2], [3], [4]. Nature provides a unique example in the lotus flower, in which the leaves utilize superhydrophobicity as the basis of a mechanism to control the surface morphology for the protection and self-cleaning of that surface [5], [6], [7], [8]. Inspired by the natural superhydrophobicity, similar mimetic surfaces with water contact angles greater than 150°, have attracted considerable interest over the past few years for both fundamental research and practical applications. Generally, in order to create a superhydrophobic surface, two strategies are adopted. One is fabricating a rough surface by using low surface energy materials; the other is preparing a rough surface first and then modifying the rough surface with low surface energy compounds. More recently, superhydrophobic surfaces with a hierarchical structure in nano-scale and micron scale mimicking that of a lotus leaf have also been reported [9], [10], [11], [12], [13], [14].

Based on previous reports, most methods for obtaining superhydrophobic surfaces typically use either expensive materials or severe conditions, limiting the applications of superhydrophobic surfaces [15], [16]. In this study, a rough surface with low surface tension exhibits superhydrophobicity and stability, which can be facilely fabricated in one step by casting the copolymer solution. Rough surface morphology, prepared by phase separation technique in the work [17], [18], is like that of nature lotus leaf. Meanwhile, the film surface roughness can be controlled by the degree of phase separation.

Section snippets

Synthesis of copolymer

A typical preparation procedure was as follows: a dry round-bottom flask was filled with styrene (St, 5 ml), 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA, 5 ml) and benzoyl peroxide (BPO, 0.17 g), [St]:[HFMA]:[BPO] = 62:38:1. After fully mixing, the flask was immersed in an oil bath at 95 °C for 8 h. After synthesis the copolymer was purified by dissolving in THF and precipitating in the mixture of methanol and water, and then the purified copolymer was placed into oven for drying. The procedure

Characterization of the copolymer

According to the results of elemental analysis, we can calculate the composition of the copolymer (see Table 1). The molar ratio of St and HFMA is 1.32 in the copolymer. PS in the copolymer is 35.4 wt%, and PHFMA in the copolymer is 64.6 wt%. According to the results of GPC measurement (See Table 2), we can know Mn, Mw and PDI of the copolymer were 34966.1 g/mol, 55544.1 g/mol and 1.59 respectively.

A typical 1H NMR spectrum, shown in Fig. 1, confirms the formation of the copolymers. The peaks at

Conclusions

The superhydrophobic films of the fluoropolymer with binary hierarchical structure can be obtained by a facile approach. The surface roughness of the films can be controlled by the degree of phase separation. When the content of ethanol was tuned to 50% by volume, the surface resembled the structure of the lotus leaf, was superhydrophobic with water contact angle 154.3° and sliding angle 5.8°. Because of the excellent performance, this fluoropolymer film is expected to be a potential candidate

Acknowledgements

This work is supported by the Youth Scientist Fund of Shandong Province (2007BS04007), the Doctoral Startup Foundation of Shandong Institute of Light Industry, National Natural Science Foundation of China (50772059) and the foundation for the author of National Excellent Doctoral Dissertation (No. 200539) for PR China.

References (18)

  • R.N. Wenzel

    Ind. Eng. Chem. Res.

    (1936)
  • A. Cassie et al.

    Trans. Faraday Soc.

    (1944)
  • S. Herminghaus

    Europhys. Lett.

    (2000)
  • W. Chen et al.

    Langmuir

    (1999)
  • W. Barthlott et al.

    Planta

    (1997)
  • L. Feng et al.

    Adv. Mater.

    (2002)
  • X. Gao et al.

    Nature

    (2004)
  • R. Blossey

    Nat. Mater.

    (2003)
  • X. Lu et al.

    Macromol. Rapid Commun.

    (2004)
There are more references available in the full text version of this article.

Cited by (74)

  • Facile fabrication of superhydrophobic surfaces via spraying with silicone-urea copolymers

    2023, Colloids and Surfaces A: Physicochemical and Engineering Aspects
  • Distribution of block copolymers in drying polymer films

    2022, Journal of Colloid and Interface Science
  • Superhydrophobic behavior of coatings based on fluoroalkyl methacrylate copolymers on a textured aluminum surface

    2021, Surfaces and Interfaces
    Citation Excerpt :

    Therefore, the textured aluminum samples were cured in solutions of FMA- and GMA-based copolymers for 1 h for uniform diffusion and orientation of macromolecular coils within the surface microtexture. The interaction between the GMA epoxy groups and hydroxyl groups of the substrate occurred under subsequent heat treatment at 140°C (Fig. 2) [25, 26]. Of note, the attachment of the FMA- and GMA-based copolymers preserved the microtexture of the aluminum surface layer obtained as a result of etching (Fig. 1 c, d).

View all citing articles on Scopus
View full text