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Icephobicity (from ''ice'' and Greek φόβος ''phobos'' "fear") is the ability of a solid surface to repel ice or prevent ice formation due to a certain topographical structure of the surface.〔Meuler, A. J. et al. Relationships between Water Wettability and Ice Adhesion. ACS Appl. Mater. Interfaces 2010, 11, 3100–3110〕〔Zheng, L. et al. Exceptional Superhydrophobicity and Low Velocity Impact Icephobicity of Acetone-Functionalized Carbon Nanotube Films. ''Langmuir'', 2011, 27, 9936–9943〕〔Jung, S.; Dorrestijn, M.; Raps, D.; Das, A.; Megaridis, C. M.; and Poulikakos, D. Are Superhydrophobic Surfaces Best for Icephobicity?. ''Langmuir'', 2011, 27, 3059–3066〕〔 〕〔Menini, R.; Ghalmi, Z.; Farzaneh, M. Highly Resistant Icephobic Coatings on Aluminum Alloys. Cold Reg. Sci. Technol. 2011, 65, 65-69〕 The word “icephobic” was used for the first time at least in 1950;〔Chemical Industries, 1950, v. 67, p. 559〕 however, the progress in micropatterned surfaces resulted in growing interest towards the icephobicty since the 2000s. As a keyword, the term “icephobic” was used for the first time in scientific literature by Kulinich & Farzaneh in 2004 〔Kulinich & Farzaneh (2004) Appl. Surf. Sci. 230:232-240〕 as well as in some industrial reports,〔Sivas SL et al “A Silicone-Based Ice-Phobic Coating for Aircraft ” 37th ISTC (2007)〕〔Laboratory Ice Adhesion test Results for Commercial Icephobic Coatings for Pratt & Whitney, May 2004, CRREL〕 and by NASA.〔〔 == Icephobicity vs. hydrophobicity == The term "icephobicity" is similar to the term hydrophobicity and other “-phobicities” in physical chemistry (oleophobicity, lipophobicity, omniphobicity, amphiphobicity, etc.). The icephobicity is different from deicing and anti-icing in that icephobic surfaces, unlike the anti-icing surfaces, do not require special treatment or chemical coatings to prevent ice formation,〔Kulinich, S. A.; Farhadi, S.; Nose, K.; and Du, X. W. Superhydrophobic Surfaces: Are They Really Ice-Repellent?. ''Langmuir'', 2011, 27, 25-29〕〔Bahadur, V.; Mishchenko, L.; Hatton, B., Taylor, J. A.; Aizenberg, J.; and Krupenkin, T. Predictive Model for Ice Formation on Superhydrophobic Surfaces. ''Langmuir'', 2011, 27 , 14143–14150〕〔 〕〔Cao, L. -L.; Jones, A. K.; Sikka, V. K.; Wu, J.; and Gao, D. Anti-Icing Superhydrophobic Coatings. ''Langmuir'', 2009, 25, 12444-12448〕 There is further parallelism between the hydrophobicity and icephobicity. The hydrophobicity is crucial for the “hydrophobic effect” and hydrophobic interactions. For two hydrophobic molecules (e.g., hydrocarbons) placed in water, there is an effective repulsive hydrophobic force, entropic in its origin, due to their interaction with the water medium. The hydrophobic effect is responsible for folding of proteins and other macro-molecules leading to their fractal shape. During ice crystal (snowflake) formation, the synchronization of branch growth occurs due to the interaction with the medium (oversaturated vapor) – is somewhat similar to the hydrophobic effect – the apparent repulsion of the hydrophobic particles due to their interaction with the medium (water). Consequently, despite the shape of snowflakes is very diverse with “no two flakes similar to each other,” most snow crystals are symmetric with each of the six branches almost identical to other five branches. Furthermore, both hydrophobicity and icephobicity can lead to quite complex phenomena, such as self-organized criticality-driven complexity as a result of hydrophobic interactions (during wetting of rough/heterogeneous surfaces or during polypeptide chain folding and looping) or ice crystallization (fractal snowflakes).〔 Note that thermodynamically both the hydrophobic interactions and ice formation are driven by the minimization of the surface Gibbs energy, ΔG = ΔH − TΔS, where H, T, and S are the enthalpy, temperature, and entropy, respectively. This is because in the hydrophobic interactions large positive value of TΔS prevails over a small positive value of ΔH making spontaneous hydrophobic interaction energetically profitable. The so-called surface roughening transition governs the direction of ice crystal growth and occurs at the critical temperature, above which the entropic contribution into the Gibbs energy, TΔS, prevails over the enthalpic contribution, ΔH, thus making it more energetically profitable for the ice crystal to be rough rather than smooth. This suggests that thermodynamically both the icephobic and hydrophobic behaviors can be viewed as entropic effects.〔 However, icephobicity is different from the hydrophobicity. Hydrophobicity is a property which is characterized by the water contact angle (CA) and interfacial energies of the solid-water, solid-vapor, and water-vapor interfaces and thus it is a thermodynamic property usually quantitatively defined as CA>90 degrees. Another difference is that the hydrophobicity is opposed to the hydrophilicity in a natural way. There is no such an opposition for the icephobicity, which should therefore be defined by setting a quantitative threshold. The icephobicity is much more similar to how the superhydrophobicity is defined.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Icephobicity」の詳細全文を読む スポンサード リンク
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