- Email: [email protected]
Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property
Applied Surface Science 355 (2015) 495–501
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property Tingting Song a , Qi Liu a , Jingyuan Liu a , Wanlu Yang a , Rongrong Chen b , Xiaoyan Jing a , Kazunobu Takahashi b , Jun Wang a,b,∗ a b
Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001, PR China Institute of Advanced Marine Materials, Harbin Engineering University, 150001, PR China
a r t i c l e
i n f o
Article history: Received 4 June 2015 Received in revised form 16 July 2015 Accepted 20 July 2015 Available online 26 July 2015 Keywords: Bioinspired Super slippery surface Sheet-layered pores EIS AAO template
a b s t r a c t Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment. © 2015 Elsevier B.V. All rights reserved.
1. Introduction With the development of science, natural creatures have attracted many researchers due to their special structures and functions. In recent years, biomemetic materials have been applied in broad fields ranging from biomedical devices [1–5], to naval vessels [6–9], which are inspired by natural plants and animals, such as lotus leaves, wings of Gerris, and gecko feet, which naturally inherit superhydrophobic characteristics [10–12]. Therefore, super hydrophobic surfaces with the properties of self-cleaning [13,26], anti-ice [14,15], anti-corrosion [16,17], self-healing [18], anti-fouling [19], and anti-frost [20], are fabricated by many methods. These include hydrothermal synthesis [16,21], electrospining [22,23], and self-assembly [24,25]. However, there are still several drawbacks, such as failing to self-healing, physical damage, high cost, resistance to high pressure and repulsion of complex liquids with low contact angle hysteresis [26–31]. To obtain better super surfaces, super slippery surfaces inspired by Nepenthes pitcher are designed. The advantageous features of the plants are: they are composed of distinguishable sections in different
∗ Corresponding author at: Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001, PR China. Tel.: +86 451 8253 3026; fax: +86 451 8253 3026. E-mail address: [email protected] (J. Wang). http://dx.doi.org/10.1016/j.apsusc.2015.07.140 0169-4332/© 2015 Elsevier B.V. All rights reserved.
functional morphologies [32,33] and they can secrete nectar liquid or absorb UV light around their opening for attracting insects [34,35]. After making contact with the pitchers, most insects fall into the traps and cannot escape. An obvious difference between super slippery surfaces and artificial superhydrophobic surfaces is due to the nature of liquid repellence. Superhydrophobicity can be explained by the Wenzel and Cassie-Baxter theories [36,37]. Nevertheless, the super slippery property depends on locking lubricating liquid in the nano/microstructure [38,39]. On the basis of the above characteristics, Wong et al. fabricated super slippery surface by infusing lubricating liquid into porous surfaces—“slippery liquid-infused porous surface(s)” (SLIPS), which possessed self-repairing [39], anti-ice and anti-frost [40,41] and anti-fouling [42] properties. Zhang et al. fabricated pyramidson-pores slippery surfaces by molding method on aluminium substrates with the properties of resistivity to acid, weak base, high temperature and organic solvents [43]. Peng et al. prepared “SLIPS” surfaces on pyramids structured aluminium also with anti-bacteria-corrosion property [44]. Kim and his co-workers constructed lubricant-infused slippery surfaces via a sol–gel method, in which the surfaces are kept smooth under a spin speed of 10 000 rpm [45]. Xue et al. made slippery superhydrophobic surfaces by chemical etching with a self-cleaning effect [46]. However, most surface morphologies on the substrates result from retextured structures, and the slippery property is performed after immersing in the lubricating liquid. It is difficult for these surfaces
496
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Scheme 1. the formation process of super slippery (a) the formation of porous AAO template after two-step anodic process on aluminium substrate; (b) the template was infused Methyl Silicon Oil; (c) the template was modified by FAS; (d) the template was immersed in lubricating oil-DuPont Krytox.
to store lubricating oil [47,48]; in other words, they lose their super slippery characteristics after a few days due to a gravity effect when the samples come into contact with air or they move [49–51]. However, maintaining slippery quality for a long time is still a pressing challenge for the provision of super slippery surfaces with excellent anticorrosion property. In this report, we fabricated super slippery AAO surface through simple elctrochemical and solution-impregnated self-assembly method according to the three criteria of super slippery surface raised by Wong et al. [39]. Firstly, we applied an electrochemical process to produce porous AAO templates (Scheme 1a) [52–58]. Then, the samples with special pores are immersed in Methyl Silicone Oil (Scheme 1b). After surface modification by FAS (Scheme 1c, also see Fig. S1 in Supporting information), the super slippery surfaces with the storage of lubricating oil based on aluminium were obtained (Scheme 1d). On the basis of the above mentioned challenge, the as-prepared super slippery AAO surfaces in our report exhibit the steady storage function, excellent anti-corrosion property and anti-low-temperature changes. Moreover, the slippery properties of as-obtained super slippery surface keep more than three months. These excellent properties of super slippery AAO surfaces may be potential candidates for metallic application in anti-corrosion and extreme environment. 2. Experimental 2.1. Materials All reagents were of analytical grade and used as received without further purification. Aluminium sheets, 0.2 mm thickness, were used as the substrate (composition: 99.5 wt% Al, 0.15 wt% Si, 0.015 wt% Cu, 0.015 wt% Fe, 0.005 wt% N), Methyl Silicone Oil, DuPont Krytox104, alcohol (Heptadecaflu-oro-1,1,2,2-tetradecyl)trimethoxysilane (FAS).
aluminium was immersed in 1 M NaOH for 5 min to remove the oxide film. After washing with distilled water and dried in the air, aluminium was electro-polished in the polishing liquid. Finally, in a two-step process, electrochemical anodizing was first introduced to prepare the ordered and sheet-layered aluminium oxide membrane in oxalic acid solution. The experimental prerequisite of the first step of electrochemical anodizing was carried out in 0.3 M oxalic acid at voltage range of 40 V and temperature range of 5–10 ◦ C for 2 h. The same conditions were adopted in the second step, but the process was for 4 h. 2.3. The fabrication of super slippery surface on AAO Aluminium templates were immersed in the Methyl Silicone Oil for 24 h, and modified by FAS for 24 h. Super slippery surfaces were fabricated after immersing in DuPont Krytox 104 for 24 h. 2.4. Characterization The surface morphologies of prepared samples were examined by Field Emission Scanning Electron Microscopy (FESEM, JEOL JSM6480A); the surfaces were sputter-coated by a thin gold layer. The surface compositions were analyzed using X-ray photo electron spectroscopy (XPS, ESCALAB 250Xi, USA, Thermo). The corrosion properties of the samples were carried out by electrochemical workstation (IM6, German, Zahner) using 3.5 wt% aqueous solutions of NaCl at room temperature. A three-electrode system was used, in which the samples with an exposed area of 1 cm2 acted as the working electrode, Ag/AgCl as reference electrode, and platinum as the counter electrode. Static water contact angles were measured by FTA200 drop shape analysis system at room temperature. The results were averaged by ten points. The photos were taken by Canon. 3. Results and discussion
2.2. AAO preparation 3.1. Morphology of aluminium templates after anodizing process Firstly, commercial aluminium (30 mm × 30 mm × 2 mm) was annealed at a temperature of 450 ◦ C to eliminate the internal stress of aluminium plates formed in the process of rolling and to obtain an appropriate size of recrystallization grains, which is conducive to the generation of uniform and sheet-layered pores on alumina membranes. Secondly, aluminium was ultrasonically degreased in ethanol for 30 min and was then rinsed with distilled water. Thirdly,
As shown in Fig. 1, the as-prepared AAO surfaces are covered by micro-nano sheet-layered and well-aligned pores in this electrochemical process. Comparing with recent research [59,60], most of the pores are self-ordered and directly aligned from top to bottom. the morphology of AAO pores (Fig. 1). The morphology of aluminium templates after the two-step
T. Song et al. / Applied Surface Science 355 (2015) 495–501
497
Fig. 1. FESEM image of porous anodic aluminium oxide after two-step anodic process (a) 1 m; (b) 300 nm.
anodizing process is shown from FESEM images (Fig. 1). The micrograph of surface and cross-section (Fig. 1a–d) shows a large amount of ordered and sheet-layered pores on aluminium templates, which can store lubricating oil steadily and release slowly for maintaining super slipperiness. The top sheet-layered pores are around 60 nm in diameter. Fig. 1b and d shows the magnification of Fig. 1a and c, respectively. In addition, a compared picture of AAO (Fig. S2a) and AAO super slippery surface (Fig. S2b) demonstrates that AAO super slippery surface is shinnier than AAO because of lubricating oil in the supporting information. However, the microscopic morphologies of these two surfaces are the same as shown in Fig. 1.
3.2. Characteristics of super slippery AAO surfaces The chemical compositions of the super slippery AAO surfaces were analyzed by XPS. There were five signals: C1s, O1s, F1s, Al2p and Si2p (Fig. 2a–d). The O1s spectrum of the super slippery AAO surface is divided into three components: the signal at around 530.6 eV is Al-O [61], which indicates aluminum oxide has formed on the surface. The other two peaks at around 531.4 eV and 529.8 eV represent C–O and C O [62], respectively (Fig. 2b). The C1s spectrum of the super slippery AAO surfaces was shown in Fig. 2c. There are two main peaks in the graph. The peaks at around 283.16 eV, 282.7 eV, 283.7 eV, 287.3 eV, 290.4 eV, 292.5 eV are assigned to C–O, C–C, C–Si, –CH2 –CF2 , –CF2 and –CF3 , respectively. The super slippery AAO surfaces were modified by a low surface energy reagent. The bond of Al2p was exhibited in Fig. 2d. The main peak, observed at around 73.1 eV on the curve (Fig. 2d), is Al3+ . The other peak at about 74.7 eV is related to aluminum suboxide formation [63], which indicates that the aluminum substrate is modified by FAS clearly.
3.3. Analysis of super slippery properties The smooth, anti-fouling and anti-creature attachment properties of surfaces were tested by water, green tea, coffee, soy sauce and ants, respectively. Water rolled from the super slippery surfaces successfully (Fig. S3). As shown in Figs. S4–S7 and Video S1–S5 in supporting information, water, green tea, coffee and soy sauce were still slipped from the surfaces easily after finger contacting. The motion of the ant on the super slippery surfaces was demonstrated in Video S6 and Fig. S8. The above mentioned data verifies that the super slippery surfaces possess the property of anti-creature adhesion. In addition, super slippery surfaces in this report could keep super slippery property for more than three months, the results from Fig. 3a–b showed 5 L WCA (water contact angle) and slide angle on super slippery surfaces. WCA and slide angle of super slippery surfaces was about 133◦ (Fig. 3a) and 4◦ (Fig. 3b), respectively. After placing super slippery surfaces in the air for about three months, WCA and slide angle of super slippery surfaces was about 118◦ (Fig. 3c) and 6◦ (Fig. 3d), respectively. The above results demonstrated that lubricating liquid evaporated a little at atmosphere environment, so WCAs were decreased, but slide angles were increased. Fig. 4 exhibits changes of WCAs and slide angles at average of ten points during three months. As shown in Fig. 4, there were no obvious changing trends in WCAs slide angles. The consequences indicated that super slippery surfaces could keep super slippery property for at least three months based on the sheet-layered pores. Moreover, the as-prepared AAO surface can immerse in super slipper liquid repeatedly when lubricating liquid evaporate thoroughly and continue to keep super slippery property. Furthermore, it also shows that the super slippery surfaces could not be affected by temperature changes. The obtained surfaces were placed at the temperature of 18 ◦ C, −15 ◦ C and −30 ◦ C, respectively. As depicted in Fig. 5a and b, there were few changes
498
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 2. XPS survey (a) and high-resolution XPS spectra of O 1s (b), C 1s (c) and Al 2p (d) of the pure aluminium substrate was immersed in the Methyl Silicone Oil and modified by FAS and lubricating oil.
Fig. 3. Water contact angle (a), slide angle (b) and water contact angle (c), slide angle (d) after placing three months in air on super slippery surfaces.
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 4. Changes of WCAs and slide angles at average of ten points during three months.
on super slippery surfaces and pure aluminum at the temperature of 18 ◦ C, and there was no still appearence of ice on super slippery surfaces at −15 ◦ C and −30 ◦ C (Fig. 5a1 and a2), while ice appeared on all of the pure aluminum at the temperature of −15 ◦ C and −30 ◦ C (Fig. 5b1 and b2). It indicates that our fabricated samples can keep stable at low temperature environment. 3.4. Corrosion resistance of super slippery surfaces in 3.5% NaCl solution Corrosion resistance of super slippery surfaces was investigated by electrochemical impedance spectroscopy (EIS). The measurement was performed on the standard three-electrode system with the 50 mV disturbing value. Nyquist and Bode plots of super slippery surfaces were shown in Fig. 6 after immersing in 3.5% NaCl solution for 25 h, 50 h, 295 h and 1008 h, respectively. From Fig. 6a, the Z value of super slippery surfaces is about 7.5E+009 and
499
7.4E+009 after immersing in 3.5% NaCl solution for 295 h and 1008 h, respectively. The above mentioned Z values have increased five orders of magnitude in comparison to those after immersing in 3.5% NaCl solution for 25 h, 50 h (Fig. 6b), and six orders of magnitude in comparison to the untreated aluminum (Fig. 7). The results demonstrate that super slippery surfaces have excellent anti-corrosion properties. It is related to the structure of AAO surface, the sheet-layered pores on AAO substrate can store lubricating oil steadily, even though the lubricating oil is released completely, the modified Methyl Silicone Oil and FAS can protect this surface from eroding. Fig. 7 shows Nyquist plots of pure aluminium after immersing in 3.5% NaCl solution for 25 h and 50 h, respectively. The untreated aluminium had been etched completely by the salty liquid after immersing in 3.5% NaCl solution for 1008 h. The electrochemical properties of the super slippery AAO surfaces can also obtained from Bode plots (Fig. 6c–d). There are two loops at 25 h and 50 h (Fig. 6b), respectively. The results are in accord with Bode plots (Fig. 6d), which appear two corresponding peaks at 25 h and 50 h, respectively, each peak representing a time constant. Two time constants of the film exist after immersing in 3.5% NaCl solution for 25 h and 50 h, respectively, which imply that the electric double layer has probably formed between the solution/film interface and the film. Besides, electrochemical behavior of the film is exhibited in Fig. 6d after immersing in 3.5% NaCl solution for 295 h and 1008 h. Furthermore, we can see a change from two time constants after immersing in 3.5% NaCl solution for 25 h and 50 h to one time constant after immersing in 3.5% NaCl solution for 295 h and 1008 h, as shown in Fig. 6d. Dense oxide membranes form on the substrates leading to excellent anti-corrosion properties. A time constant at 295 h and 1008 h is in agreement with Nyquist plots (Fig. 6a). In addition, a platform appeared in the low frequency section, which may be related to the breakage of the film after immersing in 3.5% NaCl solution for 1008 h. According to the above analysis, the super slippery surfaces of aluminium substrates have excellent anti-corrosion property.
Fig. 5. Super slippery AAO surface changes (a-a2)and pure aluminium changes (b-b2) at 18 ◦ C, −15 ◦ C and −30 ◦ C,respectively.
500
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 6. (a) EIS results of super slippery surfaces after immersing in 3.5% NaCl solution for 25 h, 50 h, 295 h, 1008 h, respectively, (b) magnification at 25 h and 50 h. (c) Bode plots of Z vs. frequency and (d) Bode plots of phase angle vs. frequency, respectively.
angles tests, the as-prepared super slippery AAO surfaces exhibit the steady storage function and slippery properties more than three months due to the micro-nano sheet-layered structure. According to EIS and Bode plots analysis, the as-prepared AAO surfaces have excellent anti-corrosion property. What’s more, the super slippery AAO surfaces also show the properties of anti-low-temperature changes, anti-creature adhesion and anti-finger contact. Therefore, such excellent properties of the as-obtained AAO surfaces may promote metallic application in extreme and anti-corrosion environment. Acknowledgements
Fig. 7. EIS image of pure aluminium after immersing in 3.5% NaCl solution for 50 h.
The excellent property of super slippery surface can be attributed to the following factors. Firstly, the micro-nano sheetlayered structure can store lubricating liquid after being modified by FAS and Methyl silicone oil, super slippery surface have such great property due to these modifiers. Secondly, aluminium substrates are performed by electrochemical anodic process generating dense oxide layers, the surface can be protected by these dense oxide layers.
This work was supported by Heilongjiang Province Natural Science Funds for Distinguished Young Scholar (JC201404), Special Innovation Talents of Harbin Science and Technology for Distinguished Young Scholar (2014RFYXJ005), Fundamental Research Funds of the Central University (HEUCFZ), Key Program of the Natural Science Foundation of Heilongjiang Province (20151008), and Program of International S&T Cooperation special project (2015DFA50050). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.apsusc.2015.07. 140
4. Conclusions In summary, the super slippery AAO surfaces have been fabricated by a simple electrochemical method with Methyl Silicone Oil, FAS and DuPont Krytox lubricating oil. Through WCAs and slide
References [1] A.M. Telford, M. James, L. Meagher, C. Neto, ACS Appl. Mater. Interfaces 2 (2010) 2399–2408.
T. Song et al. / Applied Surface Science 355 (2015) 495–501 [2] G.S. Wilson, R. Gifford, Biosens. Bioelectron. 20 (2005) 2388–2403. [3] N. Wisniewski, F. Moussy, W.M. Reichert, Fresenius J. Anal. Chem. 366 (2000) 611–621. [4] J. Wang, Electroanalysis 13 (2001) 983. [5] S.N. Olof, J.A. Grieve, D.B. Phillips, H. Rosenkranz, M.L. Yallop, M.J. Miles, A.J. Patil, S. Mann, D.M. Carberry, Nano Lett. 12 (2012) 6018–6023. [6] Q. Ye, F. Zhou, W. Liu, Chem. Soc. Rev. 40 (2011) 4244–4258. [7] J.F. Schumacher, N. Aldred, M.E. Callow, J.A. Finlay, J.A. Callow, A.S. Clare, A.B. Brennan, Biofouling 23 (2007) 307–317. [8] T. Sullivan, F. Regan, Bioinsp. Biomim. 6 (2011) 046001. [9] A.M. Brzozowska, F.J. Parra-Velandia, R. Quintana, Z. Xiaoying, S.S. Lee, L. Chin-Sing, J.G. Vancso, Langmuir 30 (2014) 9165–9175. [10] Q.F. Cheng, M.Z. Li, Y.M. Zheng, B. Su, S.T. Wang, L. Jiang, Soft Matter 7 (2011) 5948–5951. [11] W. Barthlott, C. Neinhuis, Planta 202 (1997) 1–8. [12] D.Y. Lee, D.H. Lee, S.G. Lee, K. Cho, Soft Matter 8 (2012) 4905–4910. [13] G.D. Bixler, B. Bhushan, Nanoscale 5 (2013) 7685–7710. [14] S.A. Kulinich, M. Honda, A.L. Zhu, A.G. Rozhin, X.W. Du, Soft Matter 11 (2015) 856–861. [15] R. Ramachandran, M. Nosonovsky, Soft Matter 10 (2014) 7797–7803. [16] N. Wang, D.S. Xiong, Appl. Surf. Sci. 305 (2014) 603–608. [17] N. Wang, D.S. Xiong, Y.L. Deng, Y. Shi, K. Wang, ACS Appl. Mater. Interfaces 7 (2015) 6260–6272. [18] Y. Li, S. Chen, M. Wu, J.Q. Sun, Adv. Mater. 26 (2014) 3344–3348. [19] G.D. Bixler, B. Bhushan, Nanoscale 6 (2014) 76–96. [20] M. He, J.X. Wang, H.L. Li, X.L. Jin, J.J. Wang, B.Q. Liu, Y.L. Song, Soft Matter 6 (2010) 2396–2399. [21] F. Shi, X.X. Chen, L.Y. Wang, J. Niu, J.H. Yu, Z.Q. Wang, X. Zhang, Chem. Mater. 17 (2005) 6177–6180. [22] P.S. Kumar, J. Sundaramurthy, D. Mangalaraj, D. Nataraja, D. Rajarathnamd, M.P. Srinivasan, J Colloid Interface Sci. 363 (2011) 51–58. [23] Y.I. Yoona, H.S. Moonb, W.S. Lyooc, T.S. Leea, W.H. Park, J. Colloid Interface Sci. 320 (2008) 91–95. [24] M.A. Raza, E.S. Kooij, A.V. Silfhout, H.J.W. Zandvliet, B. Poelsema, J. Colloid Interface Sci. 385 (2012) 73–80. [25] Q. Wang, Y.J. Li, B.C. Liu, Q. Dong, G.G. Xu, L. Zhang, J. Zhang, J. Mater. Chem. A 3 (2015) 139–147. [26] D. Quére, Annu. Rev. Mater. Res. 38 (2008) 71–99. [27] D. Quére, Rep. Prog. Phys. 68 (2005) 2495. [28] L. Bocquet, E. Lauga, Nat. Mater. 10 (2011) 334–337. [29] T.P.N. Nguyen, P. Brunet, Y. Coffinier, R. Boukherroub, Langmuir 26 (2010) 18369–18373. [30] R. Poetes, K. Holtzmann, K. Franze, U. Steiner, Phys. Rev. Lett. 105 (2010) 166104. [31] A. Tuteja, W. Choi, J.M. Mabry, G.H. McKinley, R.E. Cohen, Natl Acad. Sci. U.S.A. 105 (2008) 18200–18205. [32] F.E. Lloyd, The Carnivorous Plant, Ronald Press, New York, 1942. [33] B.E. Juniper, R.J. Robins, D.M. Joel, The Carnivorous Plants, Academic, London, 1989. [34] J.A. Moran, J. Ecol. 84 (1996) 515–525. [35] J.A. Moran, W.E. Booth, J.K. Charles, Ann. Bot. 83 (1999) 521–528.
501
[36] R.N. Wenzel, Ind. Eng. Chem. 28 (1936) 988–994. [37] (a) N.J. Shirtcliffe, G. McHale, M.I. Newton, C.C. Perry, Langmuir 19 (2003) 5626–5631; (b) H. Budunoglu, A. Yildirim, M.O. Guler, M. Bayindir, ACS Appl. Mater. Interface 3 (2011) 539–545. [38] C. Shillingford, N. Maccallum, T.S. Wong, P. Kim, J. Aizenberg, Fabrics coated with lubricated nanostructures display robust omniphobicity, Nanotechnology 25 (1) (2014). [39] T.S. Wong, S.H. Kang, S.K. Tang, E.J. Smythe, B.D. Hatton, A. Grinthal, J. Aizenberg, Nature 477 (2011) 443–447. [40] P. Kim, T.S. Wong, J. Alvarenga, M.J. Kreder, W.E. Adorno-Martinez, J. Aizenberg, ACS Nano 6 (2012) 6569–6577. [41] X. Sun, V.G. Damle, S. Liu, K. Rykaczewski, Bioinspired stimuli-responsive and antifreeze-secreting anti-icing coatings, Adv. Mater. Interfaces 2 (5) (2015). [42] A.K. Epstein, T.S. Wong, R.A. Belisle, E.M. Boggs, J. Aizenberg, Proc. Natl. Acad. Sci. U.S.A. 109 (2012) 13182–13187. [43] S.J. Zhu, Y.F. Li, J.H. Zhang, C.L. Lü, X. Dai, F. Jia, H.N. Gao, B. Yang, J. Colloid Interface Sci. 344 (2010) 541–546. [44] W. Peng, Z. Lu, D. Zhang, Corro. Sci. 93 (2015) 159–166. [45] K. Philseok, M.J. Kreder, J. Alvarenga, J. Aizenberg, Nano Lett. 13 (2013) 1793–1799. [46] C.H. Xue, Y.R. Li, P. Zhang, ACS Appl. Mater. Interfaces 6 (2014) 10153–10161. [47] S. Anand, K. Rykaczewski, S.B. Subramanyam, D. Beysens, K.K. Varanasi, How droplets nucleate and grow on liquids and liquid impregnated surfaces, Soft Matter 3 (1) (2015) 69–80. [48] J.S. Wexler, I. Jacobi, H.A. Stone, Shear-driven failure of liquid-infused surfaces, Phys. Rev. Lett. 114 (16) (2015) 168301. [49] S. Anand, A.T. Paxson, R. Dhiman, J.D. Smith, K.K. Varanasi, ACS Nano 6 (2012) 10122–10129. [50] J.D. Smith, R. Dhiman, S. Anand, E. Reza-Garduno, R.E. Cohen, G.H. McKinley, K.K. Varanasi, Soft Matter 9 (2013) 1772–1780. [51] K. Rykaczewski, S. Anand, S.B. Subramanyam, K.K. Varanasi, Langmuir 29 (2013) 5230–5238. [52] B. Kim, J.S. Lee, Bull. Korean Chem. Soc. 35 (2014) 349–352. ˛ [53] W.J. Stepniowski, Z. Bojar, Surf. Coat. Technol. 206 (2011) 265–272. [54] K. Nielsch, J. Choi, K. Schwirn, Nano lett. 2 (2002) 677–680. [55] S. Ono, N. Masuko, Surf. Coat. Technol. 169 (2003) 139–142. [56] G.D. Sulka, W.J. Stepniowski, Electrochim. Acta 54 (2009) 3683–3691. [57] J. Liu, S. Liu, H.H. Zhou, Thin Solid Films 552 (2014) 75–81. [58] J.G. Buijnsters, R. Zhong, N. Tsyntsaru, J.P. Celis, ACS Appl. Mater. Interfaces 5 (2013) 3224–3233. [59] S.Z. Chu, K. Wada, S. Inoue, M. Isogai, Y. Katsuta, A. Yasumori, J. Electrochem. Soc. 153 (2006) B384–B391. [60] S.Y. Zhao, K. Chan, A. Yelon, T. Veres, Adv. Mater. 19 (2007) 3004–3007. [61] N. Saleema, D.K. Sarkar, D. Gallant, R.W. Paynter, X.G. Chen, ACS Appl. Mater. Interfaces 3 (2011) 4775–4781. [62] X. Cao, T. Zhang, J.Y. Deng, L. Jiang, W.T. Yang, ACS Appl. Mater. Interfaces 5 (2013) 494–499. [63] C.S. Yang, J.S. Kim, J.W. Choi, M.H. Kwon, Y.J. Kim, J.G. Choi, G.T. Kim, J. Ind. Eng. Chem. 6 (2000) 149–156.
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property Tingting Song a , Qi Liu a , Jingyuan Liu a , Wanlu Yang a , Rongrong Chen b , Xiaoyan Jing a , Kazunobu Takahashi b , Jun Wang a,b,∗ a b
Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001, PR China Institute of Advanced Marine Materials, Harbin Engineering University, 150001, PR China
a r t i c l e
i n f o
Article history: Received 4 June 2015 Received in revised form 16 July 2015 Accepted 20 July 2015 Available online 26 July 2015 Keywords: Bioinspired Super slippery surface Sheet-layered pores EIS AAO template
a b s t r a c t Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment. © 2015 Elsevier B.V. All rights reserved.
1. Introduction With the development of science, natural creatures have attracted many researchers due to their special structures and functions. In recent years, biomemetic materials have been applied in broad fields ranging from biomedical devices [1–5], to naval vessels [6–9], which are inspired by natural plants and animals, such as lotus leaves, wings of Gerris, and gecko feet, which naturally inherit superhydrophobic characteristics [10–12]. Therefore, super hydrophobic surfaces with the properties of self-cleaning [13,26], anti-ice [14,15], anti-corrosion [16,17], self-healing [18], anti-fouling [19], and anti-frost [20], are fabricated by many methods. These include hydrothermal synthesis [16,21], electrospining [22,23], and self-assembly [24,25]. However, there are still several drawbacks, such as failing to self-healing, physical damage, high cost, resistance to high pressure and repulsion of complex liquids with low contact angle hysteresis [26–31]. To obtain better super surfaces, super slippery surfaces inspired by Nepenthes pitcher are designed. The advantageous features of the plants are: they are composed of distinguishable sections in different
∗ Corresponding author at: Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, 150001, PR China. Tel.: +86 451 8253 3026; fax: +86 451 8253 3026. E-mail address: [email protected] (J. Wang). http://dx.doi.org/10.1016/j.apsusc.2015.07.140 0169-4332/© 2015 Elsevier B.V. All rights reserved.
functional morphologies [32,33] and they can secrete nectar liquid or absorb UV light around their opening for attracting insects [34,35]. After making contact with the pitchers, most insects fall into the traps and cannot escape. An obvious difference between super slippery surfaces and artificial superhydrophobic surfaces is due to the nature of liquid repellence. Superhydrophobicity can be explained by the Wenzel and Cassie-Baxter theories [36,37]. Nevertheless, the super slippery property depends on locking lubricating liquid in the nano/microstructure [38,39]. On the basis of the above characteristics, Wong et al. fabricated super slippery surface by infusing lubricating liquid into porous surfaces—“slippery liquid-infused porous surface(s)” (SLIPS), which possessed self-repairing [39], anti-ice and anti-frost [40,41] and anti-fouling [42] properties. Zhang et al. fabricated pyramidson-pores slippery surfaces by molding method on aluminium substrates with the properties of resistivity to acid, weak base, high temperature and organic solvents [43]. Peng et al. prepared “SLIPS” surfaces on pyramids structured aluminium also with anti-bacteria-corrosion property [44]. Kim and his co-workers constructed lubricant-infused slippery surfaces via a sol–gel method, in which the surfaces are kept smooth under a spin speed of 10 000 rpm [45]. Xue et al. made slippery superhydrophobic surfaces by chemical etching with a self-cleaning effect [46]. However, most surface morphologies on the substrates result from retextured structures, and the slippery property is performed after immersing in the lubricating liquid. It is difficult for these surfaces
496
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Scheme 1. the formation process of super slippery (a) the formation of porous AAO template after two-step anodic process on aluminium substrate; (b) the template was infused Methyl Silicon Oil; (c) the template was modified by FAS; (d) the template was immersed in lubricating oil-DuPont Krytox.
to store lubricating oil [47,48]; in other words, they lose their super slippery characteristics after a few days due to a gravity effect when the samples come into contact with air or they move [49–51]. However, maintaining slippery quality for a long time is still a pressing challenge for the provision of super slippery surfaces with excellent anticorrosion property. In this report, we fabricated super slippery AAO surface through simple elctrochemical and solution-impregnated self-assembly method according to the three criteria of super slippery surface raised by Wong et al. [39]. Firstly, we applied an electrochemical process to produce porous AAO templates (Scheme 1a) [52–58]. Then, the samples with special pores are immersed in Methyl Silicone Oil (Scheme 1b). After surface modification by FAS (Scheme 1c, also see Fig. S1 in Supporting information), the super slippery surfaces with the storage of lubricating oil based on aluminium were obtained (Scheme 1d). On the basis of the above mentioned challenge, the as-prepared super slippery AAO surfaces in our report exhibit the steady storage function, excellent anti-corrosion property and anti-low-temperature changes. Moreover, the slippery properties of as-obtained super slippery surface keep more than three months. These excellent properties of super slippery AAO surfaces may be potential candidates for metallic application in anti-corrosion and extreme environment. 2. Experimental 2.1. Materials All reagents were of analytical grade and used as received without further purification. Aluminium sheets, 0.2 mm thickness, were used as the substrate (composition: 99.5 wt% Al, 0.15 wt% Si, 0.015 wt% Cu, 0.015 wt% Fe, 0.005 wt% N), Methyl Silicone Oil, DuPont Krytox104, alcohol (Heptadecaflu-oro-1,1,2,2-tetradecyl)trimethoxysilane (FAS).
aluminium was immersed in 1 M NaOH for 5 min to remove the oxide film. After washing with distilled water and dried in the air, aluminium was electro-polished in the polishing liquid. Finally, in a two-step process, electrochemical anodizing was first introduced to prepare the ordered and sheet-layered aluminium oxide membrane in oxalic acid solution. The experimental prerequisite of the first step of electrochemical anodizing was carried out in 0.3 M oxalic acid at voltage range of 40 V and temperature range of 5–10 ◦ C for 2 h. The same conditions were adopted in the second step, but the process was for 4 h. 2.3. The fabrication of super slippery surface on AAO Aluminium templates were immersed in the Methyl Silicone Oil for 24 h, and modified by FAS for 24 h. Super slippery surfaces were fabricated after immersing in DuPont Krytox 104 for 24 h. 2.4. Characterization The surface morphologies of prepared samples were examined by Field Emission Scanning Electron Microscopy (FESEM, JEOL JSM6480A); the surfaces were sputter-coated by a thin gold layer. The surface compositions were analyzed using X-ray photo electron spectroscopy (XPS, ESCALAB 250Xi, USA, Thermo). The corrosion properties of the samples were carried out by electrochemical workstation (IM6, German, Zahner) using 3.5 wt% aqueous solutions of NaCl at room temperature. A three-electrode system was used, in which the samples with an exposed area of 1 cm2 acted as the working electrode, Ag/AgCl as reference electrode, and platinum as the counter electrode. Static water contact angles were measured by FTA200 drop shape analysis system at room temperature. The results were averaged by ten points. The photos were taken by Canon. 3. Results and discussion
2.2. AAO preparation 3.1. Morphology of aluminium templates after anodizing process Firstly, commercial aluminium (30 mm × 30 mm × 2 mm) was annealed at a temperature of 450 ◦ C to eliminate the internal stress of aluminium plates formed in the process of rolling and to obtain an appropriate size of recrystallization grains, which is conducive to the generation of uniform and sheet-layered pores on alumina membranes. Secondly, aluminium was ultrasonically degreased in ethanol for 30 min and was then rinsed with distilled water. Thirdly,
As shown in Fig. 1, the as-prepared AAO surfaces are covered by micro-nano sheet-layered and well-aligned pores in this electrochemical process. Comparing with recent research [59,60], most of the pores are self-ordered and directly aligned from top to bottom. the morphology of AAO pores (Fig. 1). The morphology of aluminium templates after the two-step
T. Song et al. / Applied Surface Science 355 (2015) 495–501
497
Fig. 1. FESEM image of porous anodic aluminium oxide after two-step anodic process (a) 1 m; (b) 300 nm.
anodizing process is shown from FESEM images (Fig. 1). The micrograph of surface and cross-section (Fig. 1a–d) shows a large amount of ordered and sheet-layered pores on aluminium templates, which can store lubricating oil steadily and release slowly for maintaining super slipperiness. The top sheet-layered pores are around 60 nm in diameter. Fig. 1b and d shows the magnification of Fig. 1a and c, respectively. In addition, a compared picture of AAO (Fig. S2a) and AAO super slippery surface (Fig. S2b) demonstrates that AAO super slippery surface is shinnier than AAO because of lubricating oil in the supporting information. However, the microscopic morphologies of these two surfaces are the same as shown in Fig. 1.
3.2. Characteristics of super slippery AAO surfaces The chemical compositions of the super slippery AAO surfaces were analyzed by XPS. There were five signals: C1s, O1s, F1s, Al2p and Si2p (Fig. 2a–d). The O1s spectrum of the super slippery AAO surface is divided into three components: the signal at around 530.6 eV is Al-O [61], which indicates aluminum oxide has formed on the surface. The other two peaks at around 531.4 eV and 529.8 eV represent C–O and C O [62], respectively (Fig. 2b). The C1s spectrum of the super slippery AAO surfaces was shown in Fig. 2c. There are two main peaks in the graph. The peaks at around 283.16 eV, 282.7 eV, 283.7 eV, 287.3 eV, 290.4 eV, 292.5 eV are assigned to C–O, C–C, C–Si, –CH2 –CF2 , –CF2 and –CF3 , respectively. The super slippery AAO surfaces were modified by a low surface energy reagent. The bond of Al2p was exhibited in Fig. 2d. The main peak, observed at around 73.1 eV on the curve (Fig. 2d), is Al3+ . The other peak at about 74.7 eV is related to aluminum suboxide formation [63], which indicates that the aluminum substrate is modified by FAS clearly.
3.3. Analysis of super slippery properties The smooth, anti-fouling and anti-creature attachment properties of surfaces were tested by water, green tea, coffee, soy sauce and ants, respectively. Water rolled from the super slippery surfaces successfully (Fig. S3). As shown in Figs. S4–S7 and Video S1–S5 in supporting information, water, green tea, coffee and soy sauce were still slipped from the surfaces easily after finger contacting. The motion of the ant on the super slippery surfaces was demonstrated in Video S6 and Fig. S8. The above mentioned data verifies that the super slippery surfaces possess the property of anti-creature adhesion. In addition, super slippery surfaces in this report could keep super slippery property for more than three months, the results from Fig. 3a–b showed 5 L WCA (water contact angle) and slide angle on super slippery surfaces. WCA and slide angle of super slippery surfaces was about 133◦ (Fig. 3a) and 4◦ (Fig. 3b), respectively. After placing super slippery surfaces in the air for about three months, WCA and slide angle of super slippery surfaces was about 118◦ (Fig. 3c) and 6◦ (Fig. 3d), respectively. The above results demonstrated that lubricating liquid evaporated a little at atmosphere environment, so WCAs were decreased, but slide angles were increased. Fig. 4 exhibits changes of WCAs and slide angles at average of ten points during three months. As shown in Fig. 4, there were no obvious changing trends in WCAs slide angles. The consequences indicated that super slippery surfaces could keep super slippery property for at least three months based on the sheet-layered pores. Moreover, the as-prepared AAO surface can immerse in super slipper liquid repeatedly when lubricating liquid evaporate thoroughly and continue to keep super slippery property. Furthermore, it also shows that the super slippery surfaces could not be affected by temperature changes. The obtained surfaces were placed at the temperature of 18 ◦ C, −15 ◦ C and −30 ◦ C, respectively. As depicted in Fig. 5a and b, there were few changes
498
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 2. XPS survey (a) and high-resolution XPS spectra of O 1s (b), C 1s (c) and Al 2p (d) of the pure aluminium substrate was immersed in the Methyl Silicone Oil and modified by FAS and lubricating oil.
Fig. 3. Water contact angle (a), slide angle (b) and water contact angle (c), slide angle (d) after placing three months in air on super slippery surfaces.
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 4. Changes of WCAs and slide angles at average of ten points during three months.
on super slippery surfaces and pure aluminum at the temperature of 18 ◦ C, and there was no still appearence of ice on super slippery surfaces at −15 ◦ C and −30 ◦ C (Fig. 5a1 and a2), while ice appeared on all of the pure aluminum at the temperature of −15 ◦ C and −30 ◦ C (Fig. 5b1 and b2). It indicates that our fabricated samples can keep stable at low temperature environment. 3.4. Corrosion resistance of super slippery surfaces in 3.5% NaCl solution Corrosion resistance of super slippery surfaces was investigated by electrochemical impedance spectroscopy (EIS). The measurement was performed on the standard three-electrode system with the 50 mV disturbing value. Nyquist and Bode plots of super slippery surfaces were shown in Fig. 6 after immersing in 3.5% NaCl solution for 25 h, 50 h, 295 h and 1008 h, respectively. From Fig. 6a, the Z value of super slippery surfaces is about 7.5E+009 and
499
7.4E+009 after immersing in 3.5% NaCl solution for 295 h and 1008 h, respectively. The above mentioned Z values have increased five orders of magnitude in comparison to those after immersing in 3.5% NaCl solution for 25 h, 50 h (Fig. 6b), and six orders of magnitude in comparison to the untreated aluminum (Fig. 7). The results demonstrate that super slippery surfaces have excellent anti-corrosion properties. It is related to the structure of AAO surface, the sheet-layered pores on AAO substrate can store lubricating oil steadily, even though the lubricating oil is released completely, the modified Methyl Silicone Oil and FAS can protect this surface from eroding. Fig. 7 shows Nyquist plots of pure aluminium after immersing in 3.5% NaCl solution for 25 h and 50 h, respectively. The untreated aluminium had been etched completely by the salty liquid after immersing in 3.5% NaCl solution for 1008 h. The electrochemical properties of the super slippery AAO surfaces can also obtained from Bode plots (Fig. 6c–d). There are two loops at 25 h and 50 h (Fig. 6b), respectively. The results are in accord with Bode plots (Fig. 6d), which appear two corresponding peaks at 25 h and 50 h, respectively, each peak representing a time constant. Two time constants of the film exist after immersing in 3.5% NaCl solution for 25 h and 50 h, respectively, which imply that the electric double layer has probably formed between the solution/film interface and the film. Besides, electrochemical behavior of the film is exhibited in Fig. 6d after immersing in 3.5% NaCl solution for 295 h and 1008 h. Furthermore, we can see a change from two time constants after immersing in 3.5% NaCl solution for 25 h and 50 h to one time constant after immersing in 3.5% NaCl solution for 295 h and 1008 h, as shown in Fig. 6d. Dense oxide membranes form on the substrates leading to excellent anti-corrosion properties. A time constant at 295 h and 1008 h is in agreement with Nyquist plots (Fig. 6a). In addition, a platform appeared in the low frequency section, which may be related to the breakage of the film after immersing in 3.5% NaCl solution for 1008 h. According to the above analysis, the super slippery surfaces of aluminium substrates have excellent anti-corrosion property.
Fig. 5. Super slippery AAO surface changes (a-a2)and pure aluminium changes (b-b2) at 18 ◦ C, −15 ◦ C and −30 ◦ C,respectively.
500
T. Song et al. / Applied Surface Science 355 (2015) 495–501
Fig. 6. (a) EIS results of super slippery surfaces after immersing in 3.5% NaCl solution for 25 h, 50 h, 295 h, 1008 h, respectively, (b) magnification at 25 h and 50 h. (c) Bode plots of Z vs. frequency and (d) Bode plots of phase angle vs. frequency, respectively.
angles tests, the as-prepared super slippery AAO surfaces exhibit the steady storage function and slippery properties more than three months due to the micro-nano sheet-layered structure. According to EIS and Bode plots analysis, the as-prepared AAO surfaces have excellent anti-corrosion property. What’s more, the super slippery AAO surfaces also show the properties of anti-low-temperature changes, anti-creature adhesion and anti-finger contact. Therefore, such excellent properties of the as-obtained AAO surfaces may promote metallic application in extreme and anti-corrosion environment. Acknowledgements
Fig. 7. EIS image of pure aluminium after immersing in 3.5% NaCl solution for 50 h.
The excellent property of super slippery surface can be attributed to the following factors. Firstly, the micro-nano sheetlayered structure can store lubricating liquid after being modified by FAS and Methyl silicone oil, super slippery surface have such great property due to these modifiers. Secondly, aluminium substrates are performed by electrochemical anodic process generating dense oxide layers, the surface can be protected by these dense oxide layers.
This work was supported by Heilongjiang Province Natural Science Funds for Distinguished Young Scholar (JC201404), Special Innovation Talents of Harbin Science and Technology for Distinguished Young Scholar (2014RFYXJ005), Fundamental Research Funds of the Central University (HEUCFZ), Key Program of the Natural Science Foundation of Heilongjiang Province (20151008), and Program of International S&T Cooperation special project (2015DFA50050). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.apsusc.2015.07. 140
4. Conclusions In summary, the super slippery AAO surfaces have been fabricated by a simple electrochemical method with Methyl Silicone Oil, FAS and DuPont Krytox lubricating oil. Through WCAs and slide
References [1] A.M. Telford, M. James, L. Meagher, C. Neto, ACS Appl. Mater. Interfaces 2 (2010) 2399–2408.
T. Song et al. / Applied Surface Science 355 (2015) 495–501 [2] G.S. Wilson, R. Gifford, Biosens. Bioelectron. 20 (2005) 2388–2403. [3] N. Wisniewski, F. Moussy, W.M. Reichert, Fresenius J. Anal. Chem. 366 (2000) 611–621. [4] J. Wang, Electroanalysis 13 (2001) 983. [5] S.N. Olof, J.A. Grieve, D.B. Phillips, H. Rosenkranz, M.L. Yallop, M.J. Miles, A.J. Patil, S. Mann, D.M. Carberry, Nano Lett. 12 (2012) 6018–6023. [6] Q. Ye, F. Zhou, W. Liu, Chem. Soc. Rev. 40 (2011) 4244–4258. [7] J.F. Schumacher, N. Aldred, M.E. Callow, J.A. Finlay, J.A. Callow, A.S. Clare, A.B. Brennan, Biofouling 23 (2007) 307–317. [8] T. Sullivan, F. Regan, Bioinsp. Biomim. 6 (2011) 046001. [9] A.M. Brzozowska, F.J. Parra-Velandia, R. Quintana, Z. Xiaoying, S.S. Lee, L. Chin-Sing, J.G. Vancso, Langmuir 30 (2014) 9165–9175. [10] Q.F. Cheng, M.Z. Li, Y.M. Zheng, B. Su, S.T. Wang, L. Jiang, Soft Matter 7 (2011) 5948–5951. [11] W. Barthlott, C. Neinhuis, Planta 202 (1997) 1–8. [12] D.Y. Lee, D.H. Lee, S.G. Lee, K. Cho, Soft Matter 8 (2012) 4905–4910. [13] G.D. Bixler, B. Bhushan, Nanoscale 5 (2013) 7685–7710. [14] S.A. Kulinich, M. Honda, A.L. Zhu, A.G. Rozhin, X.W. Du, Soft Matter 11 (2015) 856–861. [15] R. Ramachandran, M. Nosonovsky, Soft Matter 10 (2014) 7797–7803. [16] N. Wang, D.S. Xiong, Appl. Surf. Sci. 305 (2014) 603–608. [17] N. Wang, D.S. Xiong, Y.L. Deng, Y. Shi, K. Wang, ACS Appl. Mater. Interfaces 7 (2015) 6260–6272. [18] Y. Li, S. Chen, M. Wu, J.Q. Sun, Adv. Mater. 26 (2014) 3344–3348. [19] G.D. Bixler, B. Bhushan, Nanoscale 6 (2014) 76–96. [20] M. He, J.X. Wang, H.L. Li, X.L. Jin, J.J. Wang, B.Q. Liu, Y.L. Song, Soft Matter 6 (2010) 2396–2399. [21] F. Shi, X.X. Chen, L.Y. Wang, J. Niu, J.H. Yu, Z.Q. Wang, X. Zhang, Chem. Mater. 17 (2005) 6177–6180. [22] P.S. Kumar, J. Sundaramurthy, D. Mangalaraj, D. Nataraja, D. Rajarathnamd, M.P. Srinivasan, J Colloid Interface Sci. 363 (2011) 51–58. [23] Y.I. Yoona, H.S. Moonb, W.S. Lyooc, T.S. Leea, W.H. Park, J. Colloid Interface Sci. 320 (2008) 91–95. [24] M.A. Raza, E.S. Kooij, A.V. Silfhout, H.J.W. Zandvliet, B. Poelsema, J. Colloid Interface Sci. 385 (2012) 73–80. [25] Q. Wang, Y.J. Li, B.C. Liu, Q. Dong, G.G. Xu, L. Zhang, J. Zhang, J. Mater. Chem. A 3 (2015) 139–147. [26] D. Quére, Annu. Rev. Mater. Res. 38 (2008) 71–99. [27] D. Quére, Rep. Prog. Phys. 68 (2005) 2495. [28] L. Bocquet, E. Lauga, Nat. Mater. 10 (2011) 334–337. [29] T.P.N. Nguyen, P. Brunet, Y. Coffinier, R. Boukherroub, Langmuir 26 (2010) 18369–18373. [30] R. Poetes, K. Holtzmann, K. Franze, U. Steiner, Phys. Rev. Lett. 105 (2010) 166104. [31] A. Tuteja, W. Choi, J.M. Mabry, G.H. McKinley, R.E. Cohen, Natl Acad. Sci. U.S.A. 105 (2008) 18200–18205. [32] F.E. Lloyd, The Carnivorous Plant, Ronald Press, New York, 1942. [33] B.E. Juniper, R.J. Robins, D.M. Joel, The Carnivorous Plants, Academic, London, 1989. [34] J.A. Moran, J. Ecol. 84 (1996) 515–525. [35] J.A. Moran, W.E. Booth, J.K. Charles, Ann. Bot. 83 (1999) 521–528.
501
[36] R.N. Wenzel, Ind. Eng. Chem. 28 (1936) 988–994. [37] (a) N.J. Shirtcliffe, G. McHale, M.I. Newton, C.C. Perry, Langmuir 19 (2003) 5626–5631; (b) H. Budunoglu, A. Yildirim, M.O. Guler, M. Bayindir, ACS Appl. Mater. Interface 3 (2011) 539–545. [38] C. Shillingford, N. Maccallum, T.S. Wong, P. Kim, J. Aizenberg, Fabrics coated with lubricated nanostructures display robust omniphobicity, Nanotechnology 25 (1) (2014). [39] T.S. Wong, S.H. Kang, S.K. Tang, E.J. Smythe, B.D. Hatton, A. Grinthal, J. Aizenberg, Nature 477 (2011) 443–447. [40] P. Kim, T.S. Wong, J. Alvarenga, M.J. Kreder, W.E. Adorno-Martinez, J. Aizenberg, ACS Nano 6 (2012) 6569–6577. [41] X. Sun, V.G. Damle, S. Liu, K. Rykaczewski, Bioinspired stimuli-responsive and antifreeze-secreting anti-icing coatings, Adv. Mater. Interfaces 2 (5) (2015). [42] A.K. Epstein, T.S. Wong, R.A. Belisle, E.M. Boggs, J. Aizenberg, Proc. Natl. Acad. Sci. U.S.A. 109 (2012) 13182–13187. [43] S.J. Zhu, Y.F. Li, J.H. Zhang, C.L. Lü, X. Dai, F. Jia, H.N. Gao, B. Yang, J. Colloid Interface Sci. 344 (2010) 541–546. [44] W. Peng, Z. Lu, D. Zhang, Corro. Sci. 93 (2015) 159–166. [45] K. Philseok, M.J. Kreder, J. Alvarenga, J. Aizenberg, Nano Lett. 13 (2013) 1793–1799. [46] C.H. Xue, Y.R. Li, P. Zhang, ACS Appl. Mater. Interfaces 6 (2014) 10153–10161. [47] S. Anand, K. Rykaczewski, S.B. Subramanyam, D. Beysens, K.K. Varanasi, How droplets nucleate and grow on liquids and liquid impregnated surfaces, Soft Matter 3 (1) (2015) 69–80. [48] J.S. Wexler, I. Jacobi, H.A. Stone, Shear-driven failure of liquid-infused surfaces, Phys. Rev. Lett. 114 (16) (2015) 168301. [49] S. Anand, A.T. Paxson, R. Dhiman, J.D. Smith, K.K. Varanasi, ACS Nano 6 (2012) 10122–10129. [50] J.D. Smith, R. Dhiman, S. Anand, E. Reza-Garduno, R.E. Cohen, G.H. McKinley, K.K. Varanasi, Soft Matter 9 (2013) 1772–1780. [51] K. Rykaczewski, S. Anand, S.B. Subramanyam, K.K. Varanasi, Langmuir 29 (2013) 5230–5238. [52] B. Kim, J.S. Lee, Bull. Korean Chem. Soc. 35 (2014) 349–352. ˛ [53] W.J. Stepniowski, Z. Bojar, Surf. Coat. Technol. 206 (2011) 265–272. [54] K. Nielsch, J. Choi, K. Schwirn, Nano lett. 2 (2002) 677–680. [55] S. Ono, N. Masuko, Surf. Coat. Technol. 169 (2003) 139–142. [56] G.D. Sulka, W.J. Stepniowski, Electrochim. Acta 54 (2009) 3683–3691. [57] J. Liu, S. Liu, H.H. Zhou, Thin Solid Films 552 (2014) 75–81. [58] J.G. Buijnsters, R. Zhong, N. Tsyntsaru, J.P. Celis, ACS Appl. Mater. Interfaces 5 (2013) 3224–3233. [59] S.Z. Chu, K. Wada, S. Inoue, M. Isogai, Y. Katsuta, A. Yasumori, J. Electrochem. Soc. 153 (2006) B384–B391. [60] S.Y. Zhao, K. Chan, A. Yelon, T. Veres, Adv. Mater. 19 (2007) 3004–3007. [61] N. Saleema, D.K. Sarkar, D. Gallant, R.W. Paynter, X.G. Chen, ACS Appl. Mater. Interfaces 3 (2011) 4775–4781. [62] X. Cao, T. Zhang, J.Y. Deng, L. Jiang, W.T. Yang, ACS Appl. Mater. Interfaces 5 (2013) 494–499. [63] C.S. Yang, J.S. Kim, J.W. Choi, M.H. Kwon, Y.J. Kim, J.G. Choi, G.T. Kim, J. Ind. Eng. Chem. 6 (2000) 149–156.