Extensive research on the preparation of superhydrophobic surfaces has been reported in the past decade, ranging from basic research to practical applications. Such surfaces usually exhibit water contact angles (CAs) larger than 1508. However, studies on superoleophobic surfaces, on which nonpolar (NP) liquid droplets (in particular, small volumes ca. 3-5 mL) that have appreciably low surface tensions (LSTs) can easily roll across and off, and which have a minimum tilt angle (TA) for droplet motion of less than 108, [1][2][3] are rare, despite of the practical advantages they offer. It is very challenging to fabricate surfaces that strongly promote dewetting of NP liquids, such as n-hexadecane and n-dodecane, because of their LSTs (g lv = 27.5 and 25.4 dyn cm À1 at 20 8C, respectively [4] ). When most superhydrophobic surfaces encounter such NP-LST liquids, they exhibit Wenzel wetting behavior: the liquid droplet sticks to the surface and does not roll off or dewet at any TA (poor dynamic oleophobicity). [5] Although textured surfaces with low surface energy usually maintain high advancing CAs (q A ), when the high-surface-tension (HST) liquid is replaced with a NP-LST one, receding CAs (q R ) are greatly decreased, which results in marked increases in CA hysteresis values (Dq = q A Àq R ). However, a few reports have described the formation of superoleophobic surfaces that are capable of preserving the excellent mobility of NP-LST liquid droplets. [2,3] Tuteja et al. [2] successfully fabricated perfluorinated patterned surfaces with a q A value of more than 1508 and TA = 158 for a 10 mL drop of n-octane (g lv = 21.8 dyn cm À1 at 20 8C [4] ). Zhang and Seeger [3] also prepared a superoleophobic surface consisting of CF 3 -terminated oxidized-silicone nanofilaments with topographical features similar to the "perfectly hydrophobic surface" reported by Gao and McCarthy. [6a] In that case, the minimum TAs needed for movement of 5 mL droplets of NP-LST liquids, such as n-decane (g lv = 23.8 dyn cm À1 at 20 8C [4] ) and nhexadecane, was only approximately 2-58. [3] For the prepara-tion of surfaces with such excellent dynamic oleophobicity, Zhang and Seeger [3] emphasized the necessity of producing weak interactions between the NP-LST droplets and the substrate surfaces.In contrast to such topographically modified surfaces, there have only been a few reports of flat or smooth surfaces with a low CA hysteresis value for both HST and NP-LST liquids. Proper control of both the molecular architecture (branched or ring-shaped molecules) and the physical nature of the modified surface (liquid-like surface that results from high mobility of functional groups in the surface-tethered molecules) are required to realize excellent dynamic dewetting behavior and to allow HST/NP-LST liquid droplets to easily dewet from the surface at low TAs, independent of the magnitude of the CA (this is a practical definition of "ultralyophobic"). [6b] Fadeev and McCarthy [7] and several other groups [8] have previously reported ultralyophobic ...

No abstract

Extensive research on the preparation of superhydrophobic surfaces has been reported in the past decade, ranging from basic research to practical applications. Such surfaces usually exhibit water contact angles (CAs) larger than 1508. However, studies on superoleophobic surfaces, on which nonpolar (NP) liquid droplets (in particular, small volumes ca. 3-5 mL) that have appreciably low surface tensions (LSTs) can easily roll across and off, and which have a minimum tilt angle (TA) for droplet motion of less than 108, [1][2][3] are rare, despite of the practical advantages they offer. It is very challenging to fabricate surfaces that strongly promote dewetting of NP liquids, such as n-hexadecane and n-dodecane, because of their LSTs (g lv = 27.5 and 25.4 dyn cm À1 at 20 8C, respectively [4] ). When most superhydrophobic surfaces encounter such NP-LST liquids, they exhibit Wenzel wetting behavior: the liquid droplet sticks to the surface and does not roll off or dewet at any TA (poor dynamic oleophobicity). [5] Although textured surfaces with low surface energy usually maintain high advancing CAs (q A ), when the high-surface-tension (HST) liquid is replaced with a NP-LST one, receding CAs (q R ) are greatly decreased, which results in marked increases in CA hysteresis values (Dq = q A Àq R ). However, a few reports have described the formation of superoleophobic surfaces that are capable of preserving the excellent mobility of NP-LST liquid droplets. [2,3] Tuteja et al. [2] successfully fabricated perfluorinated patterned surfaces with a q A value of more than 1508 and TA = 158 for a 10 mL drop of n-octane (g lv = 21.8 dyn cm À1 at 20 8C [4] ). Zhang and Seeger [3] also prepared a superoleophobic surface consisting of CF 3 -terminated oxidized-silicone nanofilaments with topographical features similar to the "perfectly hydrophobic surface" reported by Gao and McCarthy. [6a] In that case, the minimum TAs needed for movement of 5 mL droplets of NP-LST liquids, such as n-decane (g lv = 23.8 dyn cm À1 at 20 8C [4] ) and nhexadecane, was only approximately 2-58. [3] For the prepara-tion of surfaces with such excellent dynamic oleophobicity, Zhang and Seeger [3] emphasized the necessity of producing weak interactions between the NP-LST droplets and the substrate surfaces.In contrast to such topographically modified surfaces, there have only been a few reports of flat or smooth surfaces with a low CA hysteresis value for both HST and NP-LST liquids. Proper control of both the molecular architecture (branched or ring-shaped molecules) and the physical nature of the modified surface (liquid-like surface that results from high mobility of functional groups in the surface-tethered molecules) are required to realize excellent dynamic dewetting behavior and to allow HST/NP-LST liquid droplets to easily dewet from the surface at low TAs, independent of the magnitude of the CA (this is a practical definition of "ultralyophobic"). [6b] Fadeev and McCarthy [7] and several other groups [8] have previously reported ultralyophobic ...

SummaryThe attachment ability of ladybird beetles Coccinella septempunctata was systematically investigated on eight types of surface, each with different chemical and topographical properties. The results of traction force tests clearly demonstrated that chemical surface properties, such as static/dynamic de-wettability of water and oil caused by specific chemical compositions, had no significant effect on the attachment of the beetles. Surface roughness was found to be the dominant factor, strongly affecting the attachment ability of the beetles.

Various metal (Al, Ti, Fe, Ni, and Cu) surfaces with native oxide layers were rendered "omniphobic" by a simple thermal treatment of neat liquid trimethylsiloxy-terminated polymethylhydrosiloxanes (PMHSs) with a range of different molecular weights (MWs). Because of this treatment, the PMHS chains were covalently attached to the oxidized metal surfaces, giving 2-10 nm thick PMHS layers. The resulting surfaces were fairly smooth, liquid-like, and showed excellent dynamic omniphobicity with both low contact angle hysteresis (≲5°) and substrate tilt angles (≲8°) toward small-volume liquid drops (5 μL) with surface tensions ranging from 20.5 to 72.8 mN/m. Droplet mobility was improved overall as a result of heating the substrates to 70 °C. The reaction kinetics and final dynamic dewetting properties were found to be not dependent of the types of metals employed or MWs of PMHS, but mainly dominated by both reaction temperatures and reaction times.

A fluorinated and hydrophobic ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, effectively served as an advantageous lubricating liquid for the preparation of physically and chemically stable omniphobic surfaces based on slippery liquid-infused porous surfaces. Here, we used particulate microstructures as supports, prepared by the chemical vapor deposition of 1,3,5,7-tetramethylcyclotetrasiloxane and subsequent surface modification with (3-aminopropyl)triethoxysilane. Confirmed by SEM and contact angle measurements, the resulting IL-infused microtextured surfaces are smooth and not only water but also various low surface tension liquids can easily slide off at low substrate tilt angles of <5°, even after exposure to high temperature, vacuum, and UV irradiation.

Hard and transparent alumina (Al(2)O(3)) films with thicknesses in the range of 500 nm to 5 μm were successfully formed on polymethylmethacrylate (PMMA) and polystyrene (PS) surfaces. Our process is based on a lamination of anodized aluminum membranes (AAMs) to the polymer surfaces, followed by chemical etching. Because of capillary force, molten PS and liquid PMMA precursor were successfully pulled into the nanopores (10 nm diameter) within the Al(2)O(3) layers and solidified by cooling or polymerization, respectively. Our resulting AAM-laminated surfaces exhibited excellent adhesion and surface mechanical properties similar to those of fused silica, remaining crack-free and transparent even with Al(2)O(3) thicknesses exceeding 1 μm.

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