An engineered anisotropic nanofilm with unidirectional wetting properties
Source abstract
Abstract
Anisotropic textured surfaces allow water striders to walk on water, butterflies to shed water from their wings and plants to trap insects and pollen. Capturing these natural features in biomimetic surfaces is an active area of research. Here, we report an engineered nanofilm, composed of an array of poly(p-xylylene) nanorods, which demonstrates anisotropic wetting behaviour by means of a pin-release droplet ratchet mechanism. Droplet retention forces in the pin and release directions differ by up to 80 μN, which is over ten times greater than the values reported for other engineered anisotropic surfaces. The nanofilm provides a microscale smooth surface on which to transport microlitre droplets, and is also relatively easy to synthesize by a bottom-up vapour-phase technique. An accompanying comprehensive model successfully describes the film's anisotropic wetting behaviour as a function of measurable film morphology parameters.
Source: europepmc · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Surface Modification and Superhydrophobicity · Adhesion, Friction, and Surface Interactions · Nanomaterials and Printing Technologies
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (38)
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1. Huber, G. et al. Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurements. Proc. Natl Acad. Sci. USA 102, 16293–16296 (2005).10.1073/pnas.0506328102 ↗
2. Bush, J. W. M., Hu, D. L. & Prakash, M. The integument of water-walking arthropods: Form and function. Adv. Insect Physiol. 34, 117–192 (2007).10.1016/S0065-2806(07)34003-4 ↗
3. Zheng, Y. M., Gao, X. F. & Jiang, L. Directional adhesion of superhydrophobic butterfly wings. Soft Matter 3, 178–182 (2007).10.1039/B612667G ↗
4. Oelschlägel, B., Gorb, S., Wanke, S. & Neinhuis, C. Structure and biomechanics of trapping flower trichomes and their role in the pollination biology of Aristolochia plants (Aristolochiaceae). New Phytol. 184, 988–1002 (2009).10.1111/j.1469-8137.2009.03013.x ↗
5. Extrand, C. W. Retention forces of a liquid slug in a rough capillary tube with symmetric or asymmetric features. Langmuir 23, 1867–1871 (2007).10.1021/la0625289 ↗
6. Berthier, J. Microdrops and Digital Microfluidics (William Andrew, 2008).
7. Pesika, N. S. et al. Gecko adhesion pad: A smart surface? J. Phys. Condens. Matter 21, 464132 (2009).10.1088/0953-8984/21/46/464132 ↗
8. Mahdavi, A. et al. A biodegradable and biocompatible gecko-inspired tissue adhesive. Proc. Natl Acad. Sci. USA 105, 2307–2312 (2008).10.1073/pnas.0712117105 ↗
9. de Gennes, P-G., Brochard-Wyart, F. & Quéré, D. Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves (Springer, 2004).10.1007/978-0-387-21656-0 ↗
10. Khoo, H. S. & Tseng, F. G. Spontaneous high-speed transport of subnanoliter water droplet on gradient nanotextured surfaces. Appl. Phys. Lett. 95, 063108 (2009).10.1063/1.3197574 ↗
11. Ichimura, K., Oh, S-K. & Nakagawa, M. Light-driven motion of liquids on a photoresponsive surface. Science 288, 1624–1626 (2000).10.1126/science.288.5471.1624 ↗
12. Daniel, S., Sircar, S., Gliem, J. & Chaudhury, M. K. Ratcheting motion of liquid drops on gradient surfaces. Langmuir 20, 4085–4092 (2004).10.1021/la036221a ↗
13. Sandre, O., Gorre-Talini, L., Ajdari, A., Prost, J. & Silberzan, P. Moving droplets on asymmetrically structured surfaces. Phys. Rev. E 60, 2964–2972 (1999).10.1103/PhysRevE.60.2964 ↗
14. Shastry, A., Case, M. J. & Böhringer, K. F. Directing droplets using microstructured surfaces. Langmuir 22, 6161–6167 (2006).10.1021/la0601657 ↗
15. Linke, H. et al. Self-propelled Leidenfrost droplets. Phys. Rev. Lett. 96, 154502 (2006).10.1103/PhysRevLett.96.154502 ↗
16. Zhang, J., Cheng, Z., Zheng, Y. & Jiang, L. Ratchet-induced anisotropic behavior of superparamagnetic microdroplet. Appl. Phys. Lett. 94, 144104 (2009).10.1063/1.3103250 ↗
17. So, E., Demirel, M. C. & Wahl, K. J. Mechanical anisotropy of nanostructured parylene films during sliding contact. J. Phys. D 43, 045403 (2010).10.1088/0022-3727/43/4/045403 ↗
18. Demirel, M. C., Cetinkaya, M., Singh, A. & Dressick, W. J. Noncovalent deposition of nanoporous Ni membranes on spatially organized poly(p-xylylene) film templates. Adv. Mater. 19, 4495–4499 (2007).10.1002/adma.200701063 ↗
19. Malvadkar, N. A., Sekeroglu, K., Dressick, W. J. & Demirel, M. C. Noncovalent mechanism for the conformal metallization of nanostructured parylene films. Langmuir 26, 4382–4391 (2010).10.1021/la9034529 ↗
20. Malvadkar, N. A., Dressick, W. J. & Demirel, M. C. Liquid phase deposition of titania onto nanostructured poly-p-xylylene thin films. J. Mater. Chem. 19, 4796–4804 (2009).10.1039/b902882j ↗
21. Malvadkar, N. A., Park, S., Urquidi-MacDonald, M., Wang, H. & Demirel, M. C. Catalytic activity of cobalt deposited on nanostructured poly(p-xylylene) films. J. Power Sources 182, 323–328 (2008).10.1016/j.jpowsour.2008.03.060 ↗
22. Demirel, M. C. et al. Bio-organism sensing via surface enhanced Raman spectroscopy on controlled metal/polymer nanostructured substrates. Biointerphases 4, 35–41 (2009).10.1116/1.3147962 ↗
23. Boduroglu, S., Cetinkaya, M., Dressick, W. J., Singh, A. & Demirel, M. C. Controlling the wettability and adhesion of nanostructured poly-(p-xylylene) films. Langmuir 23, 11391–11395 (2007).10.1021/la7025413 ↗
24. Lee, W. et al. Nanostructure-dependent water-droplet adhesiveness change in superhydrophobic anodic aluminum oxide surfaces: From highly adhesive to self-cleanable. Langmuir 26, 1412–1415 (2010).10.1021/la904095x ↗
25. Cheng, Z., Gao, J. & Jiang, L. Tip geometry controls adhesive states of superhydrophobic surfaces. Langmuir 26, 8233–8238 (2010).10.1021/la904510n ↗
26. Quéré, D. Wetting and roughness. Ann. Rev. Mater. Res. 38, 16.1–16.29 (2008).10.1146/annurev.matsci.38.060407.132434 ↗
27. Dussan V, E. B. & Chow, R. T-P. On the ability of drops or bubbles to stick to non-horizontal surfaces of solids. J. Fluid Mech. 137, 1–29 (1983).10.1017/S002211208300227X ↗
28. Extrand, C. W. & Kumagai, Y. Liquid drops on an inclined plane: The relation between contact angles, drop shape, and retentive force. J. Colloid Interface Sci. 170, 515–521 (1995).10.1006/jcis.1995.1130 ↗
29. Nadkarni, G. D. & Garoff, S. An investigation of microscopic aspects of contact angle hysteresis: Pinning of the contact line on a single defect. Europhys. Lett. 20, 523–528 (1992).10.1209/0295-5075/20/6/009 ↗
30. de Gennes, P. G. Wetting: Statics and dynamics. Rev. Mod. Phys. 57, 827–863 (1985).10.1103/RevModPhys.57.827 ↗
31. Michael, D. H. Meniscus stability. Ann. Rev. Fluid Mech. 13, 189–216 (1981).10.1146/annurev.fl.13.010181.001201 ↗
32. Gao, L. & McCarthy, T. J. Wetting 101°. Langmuir 25, 14105–14115 (2009).10.1021/la902206c ↗
33. Extrand, C. W. Model for contact angles and hysteresis on rough and ultraphobic surfaces. Langmuir 18, 7991–7999 (2002).10.1021/la025769z ↗
34. ElSherbini, A. I. & Jacobi, A. M. Retention forces and contact angles for critical liquid drops on non-horizontal surfaces. J. Colloid Interface Sci. 299, 841–849 (2006).10.1016/j.jcis.2006.02.018 ↗
35. Prakash, M., Quéré, D. & Bush, J. W. M. Surface tension transport of prey by feeding shorebirds: the capillary ratchet. Science 320, 931–934 (2008).10.1126/science.1156023 ↗
36. Renvoisé, P., Bush, J. W. M., Prakash, M. & Quéré, D. Drop propulsion in tapered tubes. Europhys. Lett. 86, 64003 (2009).10.1209/0295-5075/86/64003 ↗
37. Courbin, L. et al. Imbibition by polygonal spreading on microdecorated surfaces. Nature Mater. 6, 661–664 (2007).10.1038/nmat1978 ↗
38. Chu, K. H., Xiao, R. & Wang, E. N. Uni-directional liquid spreading on asymmetric nanostructured surfaces. Nature Mater. 9, 413–417 (2010).10.1038/nmat2726 ↗