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We prepared superhydrophobic surfaces (SHS) with various morphologies on 7075 aluminum, demonstrating that the SHS with small nanoscale asperities of ~80 nm yielded the lowest ice adhesion forces of ~80 kPa, due to the lubricating effect of the overcooled water, and the ice menisci caused by the high surface roughness deteriorated the surface’s icephobicity. To overcome this, slippery lubricant-infused porous surfaces (SLIPS) were prepared, only to find that the removal ability of water on SLIPS was not sufficient to represent its anti-icing ability, and the ice-adhesion force on SLIPS exhibited a negative correlation with the surface roughness.

This work concentrated on the fabrication of effective slippery liquid-infused porous surfaces (SLIPSs) to robustly resist ice adhesion by using facile method and smart composition. Firstly, poly(methyl methacrylate) (PMMA), polyhedral oligomeric silsesquioxane end-functionalized PMMA (POSS-ef-PMMA) and polydimethylsiloxane-blocked PMMA (PDMS-b-PMMA) were synthesized. Secondly, micro-sized pores arranged in a three-layer honeycomb-like array at a thickness of ca. 10 μm were elicited on each surface of these three cast polymer films by breath-figure (BF) method. After a separate infiltration of polydimethylsiloxane (PDMS), poly (hydrogenmethylsiloxane) (PHMS) and hexadecane (HD) into the porous matrixes, typical SLIPSs were formed. PDMS-b-PMMA matrix with preferential lipophilicity towards PDMS endowed the obtained SLIPS with better icephobicity. However, HD-induced SLIPSs performed the lowest sliding angles at 6° for 3 μL of water droplet, the lowest ice adhesional strength ranging from 40.8–46.3 kPa and the most robust anti-icing properties of resisting more than 30 icing/de-icing cycles without changing the ice adhesional strength. Such effective anti-icing performance was ascribed to the better liquid nature of HD in contact with water and the solid nature of HD under freezing condition, which could decrease the interfacial friction and abrasion of HD against water or ice.

We present a study on materials formulation, self-assembled surface structure, and the correlation between room temperature water contact angle and contact angle hysteresis (CAH) and the icephobic property at −20 °C. Coating materials are based on TiO2-modified polysiloxane (PDMS) incorporated in the inorganic–organic hybrid (sol–gel) materials with a self-assembled surface structure induced by fluoroalkylsilane (FAS) additive and nanoparticle dispersion. A home-made single-drop ice tester is used to record the ice formation and ice sliding process on the tilted surfaces with adjustable chamber temperatures below 0 °C. It is found that a CAH less than 10°, surface roughness in the range of 10–80 nm, and a two-scale surface structure with nanospikes are the essential features for automatic ice sliding at −20 °C at a tilting angle of 30°. We achieve such features by a proper formulation of sol–gel matrix containing PDMS and 2 % FAS, with incorporation of 0.5–1 wt% alumina nanoparticle dispersion in water/solvent 1:1 ratio. Preferred particle size is about 100 nm with single peak distribution as measured by a Marvin Zetasizer. Surface morphologies of coatings are measured by atomic force microscopy technique. Coatings are applied by an air atomizing spraying process and thermally cured. Chemical analyses by XPS, FTIR, and SEM–EDX evidenced the designed composition with PDMS and fluoro-group on the coated surface. Accelerated weathering test proved the stability of the coating for at least 1000 h. Home-made single-drop ice tester (a) and the video-captured image of ice droplets on uncoated glass (b) and icephobic-coated glass during ice sliding down (c) at −20 °C.

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.

Although penguins live in the world’s coldest environment, frost and ice are seldom found on their feathers. That is to say, their feathers exhibit excellent antifrosting or anti-icing properties. We found that their air-infused microscale and nanoscale hierarchical rough structures endow the body feathers of penguins Spheniscus humboldti with hydrophobicity (water CA ≈ 147°) and antiadhesion characteristics (water adhesive force ≈ 23.4 μN), even for supercooled water microdroplets. A polyimide nanofiber membrane with novel microstructures was prepared on an asymmetric electrode by electrospinning, acting as an artificial replica of a penguin’s body feather. The unique microstructure of the polyimide nanofiber membrane results in a density gradient of the surface chemical substance, which is crucial to the formation of gradient changes of the contact angle and adhesive force. With decrease of the density of the surface chemical substance (i.e., with increase of the distance between adjacent fibers), the s...

Formation, adhesion, and accumulation of ice, snow, frost, glaze, rime, or their mixtures can cause severe problems for solar panels, wind turbines, aircrafts, heat pumps, power lines, telecommunication equipment, and submarines. These problems can decrease efficiency in power generation, increase energy consumption, result in mechanical and/or electrical failure, and generate safety hazards. To address these issues, the fundamentals of interfaces between liquids and surfaces at low temperatures have been extensively studied. This has lead to development of so called “icephobic” surfaces, which possess a number of overlapping, yet distinctive, characteristics from superhydrophobic surfaces. Less attention has been given to distinguishing differences between formation and adhesion of ice, snow, glaze, rime, and frost or to developing a clear definition for icephobic, or more correctly pagophobic, surfaces. In this review, we strive to clarify these differences and distinctions, while providing a comprehensive definition of icephobicity. We classify different canonical families of icephobic (pagophobic) surfaces providing a review of those with potential for scalable and robust development., Kuwait-MIT Center for Natural Resources and the Environment, MIT-Chevron university partnership program, Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract DAAD-19-02D-002), United States. Army Research Office, Luxembourg National Research Fund

In this work, a series of copolymer/silica nanocomposites are investigated that exhibit excellent anti-icing behavior and can be covalently grafted to any substrate containing C–H bonds with high durability. The copolymers of interest consist of pendant benzophenone, hexafluorobutyl, and a variety of other comonomers that, under mild UV irradiation, can be covalently grafted on a variety of substrates and generate a densely cross-linked network of polymer and well-dispersed nanoparticles. The robustness of thin films was compared in a series of terpolymers with different acrylic comonomer content. Thin films prepared with tert-butyl ester side groups had less backbone chain scission and, therefore, a greater extent of cross-linking than films prepared with n-butyl ester side groups. The iso-butyl acrylate comonomer promotes photoreaction efficiency in terms of kinetic rate and network robustness, leading to films that can sustain high shear forces and abrasion. The anti-icing capability of the composite was investigated using the impact of supercooled water on different substrates. The composite maintains its icephobicity after modified Taber testing with multiple abrasion cycles using a 300 g load, which demonstrates excellent mechanical resistance. In addition, this study has led to rational design rules for copolymers that maximize permanent attachment of different surface functionalities in terms of both grafting density and reaction kinetics.

Anti-icing is crucial for numerous instruments and devices in low temperature circumstance. One of the approaches in anti-icing is to reduce ice adhesion strength, seeking spontaneous de-icing processes by natural forces of gravity or by winds. In order to enable tailored surface icephobicity design, research requires a good theoretical understanding of the atomistic interacting mechanisms between water/ice molecules and their adhering substrates. Herein, this work focuses on using atomistic modeling and molecular dynamics simulation to build a nanosized ice-cube adhering onto silicon surface, with different contact modes of solid–solid and solid–liquid–solid patterns. This study provides atomistic models for probing nanoscale ice adhesion mechanics and theoretical platforms for explaining experimental results.

Excessive ice accretion on infrastructures can lead to severe damage and dysfunction. In the context of combating the build-up of unwanted icing and at the same time maintaining sunlight permeation, for instance on solar panels, windows and sensors, mechanically durable and transparent icephobic coatings are highly desired. Herein, we designed and fabricated an icephobic coating possessing for the first time combined properties of ultrafast self-healing and outperforming transparency. Our coating can restore more than 80% of the ultimate tensile strength within 45 min of healing at room temperature after introducing a cut. By a synergy of both experiments and atomistic simulations, we established the atomistic mechanism for ultrafast self-healing, i.e. the perfect balance between polymer chain flexibility and concentration of hydrogen bonding pairs. Equipped with such ultrafast self-healing property, the coating showed a stable ice adhesion strength of 52.2 ± 8.9 kPa after 20 icing/deicing cycles, and 48.2 ± 4.6 kPa after healing from mechanical damage, exhibiting exceptional robustness for anti-icing applications that required high mechanical endurance. Importantly, the coating on glass showed a light transmittance of 89.1% in the visible region, which is remarkably close to bare glass (91.9%). Moreover, the coating was recyclable due to the dissociable crosslinks, providing a sustainable aspect of the material missing in existing state-of-the-art icephobic coatings. This coating combines the properties of icephobicity, mechanical durability (via self-healing), transparency and recyclability, and thus enlightens the design of multifunctional materials for meeting complex environmental requirements encountered in the field of anti-icing. © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

The adhesion of frozen products such as dairy, water, and juices to industrial metallic surfaces is a major source of inefficiency in the food processing industry. There are different methods developed to quantify ice adhesion strength, but these methods tend to be incomparable due to a combination of tensile and shear force effects. Additionally, these methods usually involve ex-situ freezing which introduced additional experimental errors and prevent cycling of measurements. This paper proposes a new quantitative tensile force technique to characterise the tensile adhesion strength of frozen products to surfaces with less effects from the shear component of force. The in-situ freezing experimental set-up is presented along with case studies performed with commercially available milks in New Zealand to illustrate the benefits and limitations of the method. Results from this technique are not representative of the true ice adhesion strength due to effects of stress concentrations and the use of surfactants. However, this technique shows promise for comparison of the degree of icephobicity for different surfaces.

Development of an anti-icing surface on a desired industrial coating patch/object has been the persistent challenge to several industries, such as aviation and wind power. For this aim, performing surface modification to implement the icephobic property on existing commercial coatings is important for practical applications. This work accomplishes an icephobic coating overlying a PPG aerospace polyurethane coating. It manifests a clear capability to delay the formation of frost as well as to reduce the adhesion strength of ice. This icephobic coating is sustained by a unique hydrophobic heterogeneity in the micron-scale of segregation, which is realized through solution casting of a specific copolymer consisting of random rigid and soft segments, namely poly(methyl methacrylate) and poly(lauryl methacrylate-2-hydroxy-3-(1-amino dodecyl)propyl methacrylate), respectively. A wrinkled pattern developed over the coating is observed because of the diverse traits between these two segments. Besides, the OH/NH groups of the soft segment are crosslinked by a diisocyanate monomer upon drying and curing to strengthen the coating. More importantly, integration of a small dose of paraffin wax into the copolymer induces a spread of soft microdomains on the winkled pattern surface. It is hypothesized that these dual heterogeneous assemblies are responsible for the icephobicity since they instigate distinct interactions with condensed water droplets. Lastly, the thermoelectric cooling (Peltier effect) and the adhesion strength of ice on the typical coatings were assessed. This investigation also includes examination on the icephobic durability of coating, which is enhanced when a small amount of polyethylene oligomer is incorporated into the coating.

Water adhesion underlies wettabilities, and thus hydrophobicities, and defines surface properties like self-cleaning, icephobicity and many others. The nanomechanics of water adhesion, especially in the dynamic dewetting processes, has not been fully investigated. Here in this article, atomistic modeling and molecular dynamics simulations were utilized to probe the adhesion mechanics of water droplets on nanopillars and flat surfaces, covering dewetting at the Wenzel and the newly discovered monostable Cassie-Baxter states. The simulations were able to identify intermediate dewetting states on rough surfaces, resolve transition between wetting states under force. The results revealed characteristic features of dynamic water adhering stress underpinning dewetting at nanoscale, which provided deepening knowledge on surface dewetting mechanics. This work complements nanoscale dewetting experiments for new fundamental insights in studies including nanoroughness design, enhanced oil recovery, anti-icing and others. © 2018. This is the authors' manuscript to the article. The final authenticated version is available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2018/CP/C8CP03256D#!divAbstract

Formation and accretion of ice on the leading edge surface of aircrafts wings may lead to disasters. The current de-icing system for aircraft will build up weight, increase energy consumption and add complexity to the aircraft systems. Development of icephobic coatings is a potential solution to prevent ice formation and/or reduce accretion on the critical surface of aircraft. Icephobic coatings based on poly(dimethylsiloxane) (PDMS) with modification by fluorosilane and incorporation of silica nanoparticles have been fabricated. The hydrophobicity of the coatings has been measured in normal conditions with atmospheric pressure and room temperature, showing improvement of hydrophobicity by the fluorination of PDMS and incorporation of silica nanoparticles. The water droplet icing behaviour shows better anti-icing performance for fluorinated PDMS (F-PDMS)/silica coatings with a rough surface. The ice adhesion strength test results show that F-PDMS coatings without silica nanoparticles have lower ice adhesion strength implying better de-icing performance. The wettability of the coatings was also measured at reduced pressure and temperature, to study the mechanism of higher ice adhesion strength of F-PDMS/silica coatings comparing with F-PDMS based coatings. For the design and fabrication of icephobic coatings, compromise on the roughness induced hydrophobicity may become a critical requirement to avoid mechanical interlock between the ice and the rough surface.

Ice accumulation hinders the performance of, and poses safety threats for, infrastructure both on the ground and in the air. Previously, rationally designed superhydrophobic surfaces have demonstrated some potential as a passive means to mitigate ice accretion; however, further studies on material solutions that reduce impalement and the contact time for impacting supercooled droplets (high viscosity) and can also repel droplets that freeze during surface contact are urgently needed. Here we demonstrate the collaborative effect of substrate flexibility and surface micro/nanotexture on enhancing both icephobicity and the repellency of viscous droplets (typical of supercooled water). We first investigate the influence of increased viscosity (spanning from 0.9 to 1078 mPa·s using water-glycerol mixtures) on impalement resistance and the droplet-substrate contact time after impact. Then we examine the effect of droplet partial solidification on recoil and simulate more challenging icing conditions by impacting supercooled water droplets (down to -15 °C) onto flexible and rigid surfaces containing ice nucleation promoters (AgI). We demonstrate a passive mechanism for shedding partially solidified (recalescent) droplets-under conditions where partial solidification occurs much faster than the natural droplet oscillation-which does not rely on converting droplet surface energy into kinetic energy (classic recoil mechanism). Using an energy-based model (kinetic-elastic-capillary), we identify a previously unexplored mechanism whereby the substrate oscillation and velocity govern the rebound process, with low areal density and moderately stiff substrates acting to efficiently absorb the incoming droplet kinetic energy and rectify it back, allowing droplets to overcome adhesion and gravitational forces, and recoil. This mechanism applies for a range of droplet viscosities, spanning from low- to high-viscosity fluids and even ice slurries, which do not rebound from rigid superhydrophobic substrates. For a low-viscosity fluid, i.e., water, if the substrate oscillates faster than the droplet spreading and retraction, the action of the substrate is decoupled from the droplet oscillation, resulting in a reduction in the droplet-substrate contact time.

A facile and durable biomimetic slippery anti-icing coating was prepared by infusing nontoxic and inexpensive lubricating silicone oil into superhydrophobic dual-scale micro/nano-structured (MNS) aluminum surfaces. Superhydrophobic surfaces were fabricated via the combination of simple chemical etching and anodization, followed by surface modification with poly(dimethylsiloxane) (PDMS). Compared to superhydrophobic coatings, silicone oil-infused polydimethylsiloxane (SOIP) coating displays a low ice-adhesion strength of 22 ± 5 kPa on the structured surface. Moreover, the SOIP coating sustained low ice-adhesion strength (35 ± 15 kPa) even when the temperature was lowered to −25 °C. The MNS-surface exhibits excellent durability, showing a low ice-adhesion (108 kPa) after 20 icing/de-icing cycles and long-term icephobicity (55 ± 13 kPa) after four months' exposure in ambient environment. We also examined the influence of surface morphology on ice-adhesion strength, the SOIP modified MNS-surface displays better anti-icing properties compared to a nano-structured (NS) surface under harsh conditions; icing/deicing and abrasion cycles. The MNS-surface act as reservoir to hold the excess amount of oil, thus reducing the loss of lubricant during icing/deicing cycles. The proposed technique is very simple and cost-effective, and most importantly it can be applied for production of durable and scalable anti-icing coatings for various practical applications.

In spite of the substantial interest and ongoing research in the field of superhydrophobicity, the wide daily-life usability of extremely water repellent coatings is somehow impeded due to the insuperable (currently) market requirements for simultaneous possession of cost-effectiveness, profitability, scalability and long-term durability. Carbon soot, seemingly worthless substance linked primarily with the disquieting climate changes, is gaining increasing popularity as an inexpensive and inherently hydrophobic material combining multifunctional properties such as non-wettability, icephobicity, optical permeability and anti-bioadhesiveness. In this article, we suggest a simple spray coating procedure for the development of novel silver-doped soot coatings with enhanced wear resistance and anti-microbial performance. The inclusion of silver hydrogen fluoride (AgHF2) in a soot-rich ethanol solution, and its sequential spray deposition on 200 °C heated glass slides, transforms the soot into an organometallic compound capable of retaining structural integrity, excellent surface adhesion and superhydrophobicity under finger-wiping and high-impact water jetting (∼25 m/s). Furthermore, the as prepared soot coatings show good degree of wear resistance towards sandpaper abrasion, remain free of attached bacteria, slowdown the proliferation of various Gram-negative bacterial strains and exhibit satisfactory long-term durability after 105 days of prolonged residence in sea water, promoting the possibility for future “on-field” studies.

Icing is a multiphase/multiscale/multiparameter physical process, and is of frequent occurrence when suitable conditions with temperature, pressure and humidity are met. In the present work, we prepared a series of PDMS-matrix nanocomposite films with different SWCNT contents, which were endowed with hydrophobicity based on the low-surface-energy PDMS matrix and the conductivity on the SWCNT filler. Furthermore, by etching the pillar-textured structure on its surface, the nanocomposite with 5.0 wt% SWCNT was given the superhydrophobicity. These nanocomposites can be easily switched from a hydrophobic anti-icing mode to an electro-thermal deicing mode by supplying a low voltage. Using non-contact infrared thermometry, we presented an analysis of the freezing phase transition process of a single water droplet on cooling surfaces with different wettability, and investigated their ice nucleation rate and macroscopic growth velocity on these surfaces. The ice-retarding capability of superhydrophobic nanocomposite surface subjected to lots of condensed droplets was also confirmed, and understanding in light of weak contact interaction with droplets. Also under consideration is the icephobicity after freezing in terms of ice shear strength. In addition, we performed a statistical analysis about the Joule heat distribution on nanocomposite surface, the results of which demonstrated that the nanocomposite could supply a suitable heating function for active deicing, demonstrating with an energy-input deicing experiment subsequently.

Ice accretion presents a severe risk for human safety. Despite great efforts for developing icephobic surfaces (the surface with an ice adhesion strength below 100 kPa) have been devoted, expanding the lifetime of state-of-the-art icephobic surfaces still remains as a critical unsolved issue. Herein, a novel icephobic material is designed by integrating interpenetrating polymer network (IPN) into autonomous self-healing elastomer, and applied in anti-icing for enhancing mechanical durability. The molecular structure, surface morphology, mechanical properties and durable icephobicity of the material were studied. The creep behaviours of the new icephobic material, which were absent in most relevant studies on self-healing materials, were also investigated in this work. Significantly, the material showed great potentials for anti-icing applications with an ultralow ice adhesion strength of 6.0±0.9 kPa, outperforming many other icephobic surfaces. The material also exhibited extraordinary durability, showing a very low long-term ice adhesion strength of ~12.2 kPa after 50 icing/deicing cycles. Most importantly, the material was able to demonstrate self-healing from mechanical damages in a sufficiently short time, which shed light on the longevity of icephobic surface in practical applications. © American Chemical Society 2018. This is the authors accepted and refereed manuscript to the article.

Atmospheric ice that adheres to structures and accumulates is a critical issue in numerous northern areas. Even if different de-icing methods exist, they consume a great deal of energy or necessitate elaborate infrastructures. However, using coatings with icephobic properties could be the “miracle” solution. This chapter proposes a complete definition of icephobicity in line with the ice adhesion test methods used. The general way to assess this property is described using a holistic approach, the first step of which is a screening test campaign with many different candidate coatings evaluated in terms of their adhesion reduction factor (ARF). The relevance of this factor is also discussed. Further tests are recommended, after the better candidate coatings are identified, in an extensive test campaign performed under simulated icing and outdoor conditions prevailing in the real environment of the targeted application. Finally, a specific example of a test campaign in which the icephobic coatings are exposed to Arctic offshore conditions is presented.

Ice accretion causes damage on power generation infrastructure, leading to mechanical failure. Icephobic materials are being researched so that ice buildup on these surfaces will be shed before the weight of the ice causes catastrophic damage. Lubricated materials have imposed the lowest-recorded forces of ice adhesion, and therefore lubricated materials are considered the state-of-the-art in this area. Slippery lubricant-infused porous surfaces (SLIPS) are one type of such materials. SLIPS are initially very effective at repelling ice, but the trapped fluid layer that affords their icephobic properties is easily depleted by repeated icing/deicing cycles, even after one deicing event. UV-cured siloxane resins were infused into SLIPS to observe effects on icephobicity and durability. These UV-cured polymer networks enhanced both the icephobicity and longevity of the SLIPS; values of ice adhesion below 10 kPa were recorded, and appreciable icephobicity was maintained up to 10 icing/deicing cycles.

UV-curable films composed of thiol-terminated fluorosilicone methacrylate triblock copolymers (PDMS-b-(PFMA-SH)2), thiol-functionalized PDMS (PDMS-SH) and octavinyl POSS (OVPOSS) were developed for the purpose of icephobic application. The PDMS-b-(PFMA-SH)2 copolymers were firstly synthesized via reversible addition–fragmentation chain transfer polymerization of dodecafluoroheptyl methacrylate (12FMA) or 2-perfluorooctylethyl methacrylate (17FMA), and followed by thiol-modification of the end groups. The results of differential scanning calorimetry and X-ray diffraction revealed the presence of perfluoroalkyl side groups in P17FMA as presented in the crystalline structure. These endowed the P17FMA-containing films with higher receding contact angles (100.2–113.5°) as compared with the P12FMA-containing films. In icephobicity investigations of the prepared films, it was found that the rebound of the impacting droplet was influenced by the receding contact angle, surface roughness, and temperature of the film surface. Water droplets could rebound from the horizontal and tilted (30° and 45°) P17FMA-containing film surfaces down to −15 °C, allowing surface dewetting before the water droplets froze, while the droplets adhered to the P12FMA-containing film surfaces. Moreover, the ice shear strengths of all the prepared film surfaces were lower than 210 kPa, only about 15% of the value on the bare aluminum surface. Therefore, P17FMA-containing UV-curable films could be a potential candidate for icephobic applications.

A facile process to fabricate icephobic surfaces was developed by spin-coating the polydimethylsiloxane- b -poly(fluorinated acrylate) (PDMS- b -PFA) block copolymers on the substrate. The surface microstructure and chemical composition of the block copolymer films can be adjusted by changing the PDMS content. Icephobic properties of the copolymer surface were mainly ascribed to “flexible-hard” microphase separation and the ratio of fluorine to silicon. The appropriate microphase domain size and the fluorine/silicon ratio could weaken the interaction of ice and copolymer surface and delay icing of water droplets on the copolymer surface. The copolymers containing 15 wt.% PDMS showed the most outstanding icephobicity by depressing the interaction between ice and the copolymer surface.

Sol-gel coatings with different roughness and surface energy were prepared on glass substrates. Methyl triethoxysilane (MTEOS), 3-Glycidyloxypropyl trimethoxysilane (GLYMO) and fluoroalkylsilane (FAS) were used to obtain a mechanically robust icephobic coating. Different amount of hydrophobic silica nano particles was added as fillers to introduce different roughness and surface energy to the coatings. The microstructure, roughness, and surface energy, together with elemental information and surface chemical state, were investigated at room temperature. The contact angle and sliding angle were measured at different temperatures to correlate the wetting behavior at low temperature with the anti-icing performance. The ice adhesion shear strength was measured inside an ice chamber using a self-designed tester. The factors influencing the ice adhesion were discussed, and the optimum anti-icing performance found in the series of coatings. It was found that lower surface energy leads to lower ice adhesion regardless of the roughness, while the roughness plays a more complicated role. The wetting behavior of the droplet on surface changes as temperature decreases. The anti-icing performance is closely related to the antiwetting property of the surfaces at subzero temperatures.

Here, we show how to predictably impart extremely low ice adhesion to a range of different plastic materials., Ice accretion remains a costly, hazardous concern worldwide. Icephobic coatings reduce the adhesion between ice and a surface. However, only a handful of the icephobic systems reported to date reduce the ice adhesion sufficiently for the facile and passive removal of ice, such as under its own weight or by mild winds. Most of these icephobic surfaces have relied on sacrificial lubricants, which may be depleted over time, drastically raising the ice adhesion. In contrast, surfaces that use interfacial slippage to lower their adhesion to ice can remain icephobic indefinitely. However, the mechanism of interfacial slippage, as it relates to ice adhesion, is largely unexplored. We investigate how interfacial slippage reduces the ice adhesion of polymeric materials. We propose a new, universally applicable framework that may be used to predict the reduction in the adhesion of ice to surfaces exhibiting interfacial slippage. This framework allows one to rationally engender icephobicity in essentially any polymeric system, including common thermoplastics. Hence, we present several new, extremely icephobic systems fabricated from a wide range of materials, including everyday engineering plastics and sustainable, natural oils.

Minimizing adhesion of ice has been the subject of extensive studies because of importance to applications such aircraft wings, spacecraft, and power transmission wires. A growing interest concerns coatings for wind turbine blades and refrigeration. Herein, a new laboratory test was employed to obtain the thickness dependence of ice adhesion for Sylgard 184-a filled polydimethylsiloxane elastomer. A correlation between ice adhesion and coating thickness (t) was found that follows a relationship developed by Kendall over 40 years ago for removal of a rigid object from an elastomer. With a 0.05 mm/s probe speed a nearly linear relationship between peak removal stress (Ps) and 1/t(1/2) was obtained with Ps ∼ 460 kPa for an 18 μm coating, decreasing to ∼120 kPa for 533 μm. Preliminary results suggest that below ∼10 μm Ps departs from the 1/t(1/2) correlation while above ∼500 μm a limiting value for Ps may be reached. We previously reported that probe speed has negligible effect on the glassy polymer PMMA. In contrast, probe speed is identified as an important variable for testing ice release on elastomeric Sylgard 184 coatings. While work of adhesion, which is related to surface free energy, is recognized as an important factor that can affect ice release, the results reported herein show that coating thickness can override this single parameter for elastomeric substrates.

Accumulation of ice to surfaces brings dangerous and costly problems to our daily life. In this paper, an anti-ice coating inspired by ice skating is reported. Hyaluronic acid is used in the anti-ice coating to form aqueous lubricating layer benefitting from its high water absorbing property. Dopamine, the main component of the mussel adhesive protein, is introduced to anchor the hyaluronic acid to the solid surfaces to render the coating applicable to all types of solid surfaces. At the same time it serves as the crosslinking agent for hyaluronic acid, thus the thickness of the water collecting film could be easily varied. Ice adhesion strength on surfaces coated with such kind of coating could be more than one order of magnitude lower than that of uncoated ones. The results indicate that this anti-ice coating with the aqueous lubricating layer has great potential for fighting against icing problems.

Superhydrophobic coatings are reported as promising candidates for anti-icing applications. Various studies have shown that as well as having ultra water repellency the surfaces have reduced ice adhesion and can delay water freezing. However, the structure or texture (roughness) of the superhydrophobic surface is subject to degradation during the thermocycling or wetting process. This degradation can impair the superhydrophobicity and the icephobicity of those coatings. In this review, a brief overview of the process of droplet freezing on superhydrophobic coatings is presented with respect to their potential in anti-icing applications. To support this discussion, new data is presented about the condensation of water onto physically decorated substrates, and the associated freezing process which impacts on the freezing of macroscopic droplets on the surface. Refereed/Peer-reviewed

Lotus (Nelumbo nucifera) is known for its two remarkable properties: superhydrophobicity and thermogenesis; however, the relationship between these two properties remains obscure. Most botanists agree that thermogenesis helps to attract pollinators, while non-wetting helps to catch pollinators and prevents contamination. Here we investigate the surface micro- and nanotopography and wetting properties of eastern skunk cabbage (Symplocarpus foetidus), another thermogenic plant, which is known for its ability to melt snow. The skunk cabbage leaves are hydrophobic but not superhydrophobic, and they have high contact angle hysteresis (similar to the rose petal effect). We develop a heat transfer model to relate icephobicity with heat transfer and discuss the biomimetic potential that both thermogenic and superhydrophobic plants may have for icephobicity in soft materials.

A super-hydrophobic surface has been obtained from nanocomposite materials based on silica nanoparticles and self-assembled monolayers of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) using spin coating and chemical vapor deposition methods. Scanning electron microscope images reveal the porous structure of the silica nanoparticles, which can trap small-scale air pockets. An average water contact angle of 163° and bouncing off of incoming water droplets suggest that a super-hydrophobic surface has been obtained based on the silica nanoparticles and POTS coating. The monitored water droplet icing test results show that icing is significantly delayed by silica-based nano-coatings compared with bare substrates and commercial icephobic products. Ice adhesion test results show that the ice adhesion strength is reduced remarkably by silica-based nano-coatings. The bouncing phenomenon of water droplets, the icing delay performance and the lower ice adhesion strength suggest that the super-hydrophobic coatings based on a combination of silica and POTS also show icephobicity. An erosion test rig based on pressurized pneumatic water impinging impact was used to evaluate the durability of the super-hydrophobic/icephobic coatings. The results show that durable coatings have been obtained, although improvement will be needed in future work aiming for applications in aerospace.

Icephobicity is intrinsically affected by rough asperities and the surface voids provide anchoring points for the ice. The anchor of ice is likely to form on the surface under high humidity conditions. In-situ water condensation and icing observation were conducted to understand water condensation and ice retracting patterns in controlled humidity, pressure and temperature conditions. It was observed that water micro-condensation and icing occurred on rougher surfaces and the water droplets condensed along the surface cracks of the superhydrophobic polydimethylsiloxane (PDMS) based nanocomposite coatings. Further analysis revealed that ice anchoring was present on both aluminum and superhydrophobic coating surface, but it was more severe and intensified on the as-received aluminum substrates. No water condensation or subsequent icing was found on smooth PDMS hydrophobic surfaces due to the incapacity of the smooth surfaces to anchor water drops. It is the first time to validate ice anchoring over retracting ice on different wettability surfaces from in-situ icing observation. Ice adhesion strengths were also measured on the studied surfaces and the results indicated a strong linkage between centrifugal shearing of ice and anchoring mechanism due to surface rough voids, and there was no clear relevancy between ice adhesion strength and the surface wettability or hydrophobicity.

Hierarchical superhydrophobic and icephobic films on the aluminum substrates were prepared via a facile hydrothermal reaction method at 60 °C after the simple chemical modification. The results from the scanning electron microscopy observations and the X-ray diffraction patterns indicated that the micro/nanoscale hierarchical surfaces composed of bayerite microrods and Zn–Al LDH nanowalls structures. The static contact angle (CA) and sliding angle (SA) for the prepared surfaces were observed about 167.3° and 3°, respectively. Icing behavior of the surfaces was investigated in −10 °C environment. Ice adhesion was evaluated by spinning the samples at constantly increasing speed until ice delaminated. The experimental observations on the freezing time of the different surfaces demonstrated well that such prepared films exhibited the satisfactory icephobicity.