The topography and wettability of the underside of English weed (Oxalis pes-caprae) leaves and of their biomimetic replicas are investigated. Polyvinyl siloxane molds were cast from the leaves and then filled with an epoxy pre-polymer to produce replicas. The particular topographical structures of leaves and replicas were evaluated by optical microscopy and Scanning Electron Microscopy (SEM) analysis. The static wettability of leaves and replicas was assessed by contact angle measurements, while the dynamic wettability was characterized by estimating contact angle hysteresis and studying the dynamic behavior of impacting water droplets. A smooth glass slip and its replica were used as control surfaces. The replica moulding method used was able to transfer the characteristic pattern of irregular 100 µm − 200 µm × 60 µm convex papillae interspersed with stomata of the original leaf to the epoxy replicas. The static contact angle of 143° ± 3° and the contact angle hysteresis of 2° indicate that the underside of the English weed leaf is close to superhydrophobic. The lower contact angles (130° ± 4°) and higher hysteresis (31°) observed for the replica when compared with the original leaves were associated to an inaccurate replication of the chemistry and structures of the three-dimensional wax projections covering the plant surface. Also, trichomes in the original leaves could not be accurately reproduced due to their flexibility and fragility. Differences in wetting behavior were also evident from droplet impact experiments, with rebound regimes prevailing in the original leaves and regimes characterized by higher adhesion and larger dissipation predominating in the replicas. Nevertheless, the morphological features of the leaf transferred to the replica were sufficient to promote a clear hydrophobic behavior of the replica when compared with the smooth epoxy reference surface.
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Bhushan B, Her E K. Fabrication of superhydrophobic surfaces with high and low adhesion inspired from rose petal. Langmuir, 2010, 26, 8207–8217.
Ye H, Yuan Z, Zhang S. The heat and mass transfer analysis of a leaf. Journal of Bionic Engineering, 2013, 10, 170-176.
Yuan Z, Ye H, Li S. Bionic leaf simulating the thermal effect of natural leaf transpiration. Journal of Bionic Engineering, 2014, 11, 90–97.
Koch K, Bhushan B, Barthlott W. Diversity of structure, morphology and wetting of plant surfaces. Soft Matter, 2008, 4, 1943.
Koch K, Barthlott B. Superhydrophobic and superhydrophilic plant surfaces: An inspiration for biomimetic materials. Philosophical Transactions of the Royal Society A: Mathematical, Physical Engineering Sciences, 2009, 367, 1487–1509.
Bhushan B. Bioinspired structured surfaces. Langmuir, 2012, 28, 1698–1714.
Zorba V, Stratakis E, Barberoglou M, Spanakis E, Tzanetakis P, Anastasiadis S H, Fotakis C. Biomimetic artificial surfaces quantitatively reproduce the water reoellency of a lotus leaf. Advanced Materials, 2008, 20, 4049–4054.
Feng L, Zhang Y, Xi J, Zhu Y, Wang N, Xia F, Jiang L. Petal effect: A superhydrophobic state with high adhesive force. Langmuir, 2008, 24, 4114–4119.
Wan F, Pei X, Yu B, Ye Q, Zhou F, Xue Q. Grafting polymer brushes on biomimetic structural surfaces for anti-algae fouling and foul release. Applied Materials and Interfaces, 2012, 4, 4557–4565.
Barthlott W, Schimmel T, Wiersch S, Koch K, Brede M, Barczewski M, Walheim S, Weis A, Kaltenmaier A, Leder A, Bohn H F. The Salvinia paradox: Superhydrophobic surfaces with hydrophilic pins for air retention under water. Advanced Materials, 2010, 22, 2325–2328.
Vignolini S, Rudall P J, Rowland A V, Reed A, Moyroud E, Faden R B, Baumberg J J, Glover B J, Steiner U. Pointillist structural color in Pollia fruit. Proceedings of the National Academy of Sciences, 2012, 109, 15712–15715.
Koch K, Schulte AJ, Fisher A, Gorb S N, Barthlott W. A fast, precise and low-cost replication technique for nano-and-high-aspect ratio structures of biological and artificial surfaces. Bioinspiration & Biomimetics, 2008, 3, 046002.
DellaGreca M, Previtera L, Purcaro R, Zarrelli A. Cinnamic ester derivatives from Oxalis pes-caprae (Bermuda Buttercup). Journal of Natural Products, 2007, 10, 1664–1667.
Argiropoulus A, Rhizopoulou S. Micromorphology of the petals of the invasive weed, Oxalis pes-caprae. Weed Biology and Management, 2012, 12, 47–52.
Vogler E A. Surface modification for biocompatibility. In Lakhtakia A, Martin-Palma R J eds., Engineered Biomimicry, Elsevier, 2013, 189–220.
Herminghaus S, Brinkmann M, Seemann R. Wetting and dewetting of complex surface geometries. Annual Review of Materials Research, 2008, 38, 10121.
Wenzel R N. Resistance of solid surfaces to wetting by water. Industrial and Engineering Chemistry, 1936, 28, 988–994.
Cassie A B, Baxter S. Wettability of porous surfaces. Transactions of the Faraday Society, 1944, 40, 546–451.
Marmur A. Measures of wettability of solid surfaces. The European Physical Journal Special Topics, 2011, 197, 193–198.
Moreira A L N, Moita A S, Panao M R. Advances and challenges in explaining fuel spray impingement: How much of single droplet impact research is useful? Progress in Energy and Combustion Science, 2010, 36, 554–580.
Rioboo R, Tropea C, Marengo M. Outcome from a drop impact on solid surfaces. Atomization and Sprays, 2001, 11, 155–165.
Moita A S, Moreira A L N. Drop impacts onto cold and heated rigid surfaces: Morphological comparisons, disintegration limits and secondary atomization. International Journal of Heat and Fluid Flow, 2007, 28, 735–752.
Cheng P. Automation of Axisymmetric Drop Shape Analysis using Digital Imaging Processing, PhD thesis, University of Toronto, Canada, 2008.
Kietzig A M. Comments on “An essay on contact angle measurements” — An illustration of the respective influence of droplet deposition and measurement parameters. Plasma Processes and Polymers, 2008, 8, 1003–1009.
Rioboo R, Marengo M, Tropea C. Time evolution of liquid drop impact onto solid, dry surfaces. Experiments in Fluids, 2002, 33, 112–124.
Koch K, Dommisse A, Barthlott W, Gorb S N. The use of plant waxes as templates for micro- and nanopatterning of surfaces. Acta Biomaterialia, 2007, 3, 905–909.
Bhushan B, Jung Y C, Niemietz A, Koch K. Lotus-like biomimetic hierarchical structures developed by the self-assembly of tubular plant waxes. Langmuir, 2009, 25, 1659–1666.
Bhushan B, Jung Y C. Natural and biomimetic artificial surfaces for superhydrophobicity, self-cleaning, low adhesion and drag reduction. Progress in Material Sciences, 2011, 56, 1–108.
Jung Y C, Bhushan B. Dynamic effects of bouncing water droplets on superhydrophobic surfaces. Langmuir, 2008, 24, 6262–6269.
Stratakis E, Ranella A, Fotakis C. Biomimetic micro/nanostructured functional surfaces for microfluidic and tissue engineering applications. Biomicrofluidics, 2011, 5, 13411.
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Pereira, P.M.M., Moita, A.S., Monteiro, G.A. et al. Characterization of the topography and wettability of English weed leaves and biomimetic replicas. J Bionic Eng 11, 346–359 (2014) doi:10.1016/S1672-6529(14)60048-2
- biomimetic surfaces
- oxalis pes-caprae
- English weed
- replica molding