© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 wileyonlinelibrary.com COMMUNICATION Superamphiphobic Polymeric Surfaces Sustaining Ultrahigh Impact Pressures of Aqueous High- and Low- Surface-Tension Mixtures, Tested with Laser-Induced Forward Transfer of Drops Kosmas Ellinas, Marianneza Chatzipetrou, Ioanna Zergioti, Angeliki Tserepi, and Evangelos Gogolides* K. Ellinas, Dr. A. Tserepi, Dr. E. Gogolides Institute of Nanoscience and Nanotechnology NCSR “Demokritos” 153 10 Aghia Paraskevi, Attiki, Greece E-mail: e.gogolides@inn.demokritos.gr M. Chatzipetrou, Prof. I. Zergioti National Technical University of Athens Physics Department Iroon Polytehneiou 9, 15780 Zografou, Athens, Greece DOI: 10.1002/adma.201405855 can sustain ultrahigh drop impact pressures (tens to hundreds of atmospheres). [12] However, lotus-leaf surfaces remain the only solution in applications incompatible with the use of liq- uids used in the SLIPS surfaces. Many techniques to probe the thermodynamic sta- bility of artificial superamphiphobic surfaces have already been employed, [21] such as: pressure experiments, [22] drop impact, [23,24] electrowetting experiments, [25] or underwater immersion, [16] but most of them are limited as far as the max- imum pressure that can be induced. The laser-induced forward transfer (LIFT) technique is commonly used for biomolecule printing applications. [26] Liquid jets created by LIFT can reach extremely high speeds exceeding 270 m s -1 . [27] The impact of such a jet on a solid surface creates a dynamic pressure as high as 35 MPa (350 atm), enabling sticking of droplets on super- hydrophobic surfaces and evaluation of the critical pressure threshold for the transition from Cassie–Baxter (CB) to the Wenzel (W) regime. Previously, LIFT has been used to make droplets stick on random, plasma textured for few minutes (<10 min), superhydrophobic surfaces, using very high laser fluences (up to 1300 mJ cm -2 ). [27] Here, we produce hierarchical micro-nanotextured random or (quasi-)ordered material surfaces using plasma etching as described in the Supporting Information and in previous pub- lications. [28] The method is generic and can be applied on any polymeric material surface, poly(methyl methacrylate) (PMMA) being the example material surface used in this work. To char- acterize these material surfaces, we adapt the LIFT method to probe systematically their thermodynamic stability and estimate the pinning pressure for a wide range of mixtures with surface tension between 36 and 66 mN m -1 . We present evidence that careful surface topography design (spacing, diameter, height, and re-entrant profile of the sub-micrometer columns and for- mation of nanoscale roughness, i.e., geometrical parameters that can be controlled by the etching process), in combination with a defect-free hydrophobic coating can lead to superamphi- phobic surfaces with extreme pressure and mechanical endur- ance exceeding 36 atm for phosphate buffer (i.e., more than five times higher than the state-of-the-art, [2] and 7 atm for a low- surface-tension buffer/propanol mixture (36 mN m -1 ) (orders of magnitude higher than previously reported for oils [19] even after ten simultaneous high velocity impacts on the same area, expanding their spectrum of potential applications. The development of material surfaces repelling a wide range of liquids has attracted scientific attention for over a decade. Lotus leaf-like and other biomimetic materials with superhy- drophobic, and superoleophobic properties have been prepared, and many reports about such artificial superamphiphobic (superoleophobic and superhydrophobic) materials exist in the literature. [1–4] These materials are important in many fields of applications as described in some recent review papers. [5,6] Nowadays, the main focus is given in the characterization of such surfaces [7] and in the optimization of their mechanical, [8,9] environmental, [10] chemical, [11] and thermodynamic robust- ness. [12] This consistent effort has produced a wide range of new testing methods and optimized materials with respect to their mechanical and environmental stability as well as their chemical resistance to organic solvents. [11,13–18] The “lotus- leaf” type of surfaces allow the rolling of water and oil drops on them, but are usually impregnated when drops impact on them with a large pressure, or when they are submerged in liq- uids at a high pressure (or large depth). Nevertheless, a recent review paper [2] shows that examples of lotus-leaf-inspired sur- faces, exhibiting stability against high water pressures reaching 7 atm, exist in the literature, raising hopes for improved perfor- mance of lotus-leaf surfaces. However, resistance to the impact of drops of liquids or mixtures with low surface tension (similar to that of oils or alkanes) is even more difficult, and the highest reported pressures are well below 1 atm for low-surface-tension liquid droplets with low impact velocities. [19] Recent studies suggest that implementation of nanoscale roughness is essen- tial to achieve high thermodynamical stability. [16,20] An alterna- tive solution would be to replace air with a liquid to impregnate the micro- and nanotopography of a material surface, the so- called slippery liquid infused porous surfaces (SLIPS), which Adv. Mater. 2015, DOI: 10.1002/adma.201405855 www.advmat.de www.MaterialsViews.com