Icephobic Surfaces Research Articles

Ice accretion on superhydrophobic aluminum surfaces under low-temperature conditions

Abstract An icephobic surface is always desirable for high voltage overhead transmission lines to reduce ice formation on their aluminum surface, especially in a low temperature and high humidity environment. This work studied the effects of two hydrophobic coatings when applied on aluminum surfaces under cold and raining conditions in an artificial climatic chamber. Compared with bare hydrophilic aluminum surfaces, the aluminum surfaces coated with hydrophobic room temperature vulcanized silicone rubber (RTV SR) did resist ice formation but was covered by a layer of ice after 30 min of spraying supercooled water. However, a superhydrophobic coating can largely prevent ice formation on the surface except a few ice growth spots at a working temperature of − 6 °C. Furthermore, such coating keeps average water contact angles larger than 150° even at a working temperature of − 10 °C. This highly icephobic performance of the above samples is mainly attributed to the superhydrophobic property of the coating, which was obtained on micronanoscale structured aluminum surfaces after the low surface-energy stearic acid treatment.

Peroxide-activated paint removers in aerospace applications

Low surface energy materials have been extensively investigated for building icephobic surfaces in recent years. Polydimethylsiloxane (PDMS) and fluoropolymers have been introduced to this field, while control of their structures is of importance to produce deicing surfaces. In this work, fluorinated methacrylate block copolymers containing polyhedral oligomeric silsesquioxane (POSS) moieties were synthesized by reversible addition-fragmentation chain transfer polymerization and transformed into thiolated-copolymers by aminolysis to adjust the self-assembly and modify surface morphology. The icephobic coatings were developed via UV-curable thiol-ene reaction with tunable amounts of thiol-modified POSS-fluorinated methacrylate diblock copolymers with vinyl-functionalized PDMS and thiol-functionalized PDMS. Characterizations of atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle showed the evidence of the POSS-fluorinated diblock copolymers on the outmost surface of the coatings. Owing to the crystallization of perfluoroalkyl side groups, the coatings containing thiol-modified poly(methacrylisobutyl POSS)-b-poly(2-perfluorooctylethyl methacrylate) (S17F) exhibited excellent icephobicity, and water droplets could rebound completely on all S17F-containing surfaces at both normal and tilt modes before freeze even at −15 °C. The ice shear strengths of the prepared UV-cured coatings were about one-eighth of that on bare aluminum surface, while the coating containing 5% S17F achieved the lowest ice shear strength of 105 ± 12 kPa. It was found that the icephobicity of these coatings were attributed primarily to the synergistic effect of the POSS-fluorinated methacrylate diblock copolymer and the PDMS component.

Aircraft icing

Aircraft icing

Comments on “Influence of temperature and hydroxyl concentration on incipient soot formation in premixed flames,” by M. M. Harris, G. B. King, and N. M. Laurendeau

The carbon soot has generally negative connotation due to the adverse impact on the human health and ambient environment. Most of the studies involving soot analysis focus on the need of preventing or reducing the sources of soot production. However, if the atmospheric soot aerosols are capable of repelling the ambient water vapor and thus impeding the water film formation on the soot particles’ outer shell, they can be considered as competitive and cost-effective candidates for the development of multifunctional non-wettable coatings. The physicochemistry of the soot, particularly the surface oxidation, the presence of heteroatoms and the degree of surface heterogeneity, regulates its chemical non-polarity and hygroscopicity. Appropriately selecting the types of soot sources facilitates the material’s recycling into a liquid-repellent tool with potential applicability in cryobiology, medicine, water purification devices, desalination systems, passive anti-bioadhesive and icephobic surfaces. This review article summarizes for the first time the main soot aerosol patterns based on their water uptake and provides detailed guidelines for the choice of suitable coating fabrication protocol and successive chemical processing. The latter are determinative factors in designing mechanically robust soot withstanding the impact of gusty winds, water jetting, abrasion or finger wiping. Finally, the state-of-the-art in the practical relevance of the hydrophobic soot is discussed, while the existing limitations and the future trends in the soot coatings technology are outlined.