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This study examines the efficacy of icephobic polyurethane nanocomposite coatings in mitigating corrosion on an aluminum substrate. A titanium-based conversion coating is applied to modify the substrate, and the research focuses on optimizing the dual functionalities of icephobicity and anticorrosion within the polyurethane coatings while ensuring strong substrate adhesion. The coatings are formulated using fluoropolyol, isocyanate, and silica nanoparticles treated with polydimethylsiloxane. Surface properties are analyzed using contact angles, contact angle hysteresis measurements, and atomic force microscopy, and the coatings' icephobicity is evaluated through differential scanning calorimetry, freezing time delay, ice adhesion under impact and non-impact conditions, and ice accretion tests. The corrosion resistance and adhesive strength of the coatings are assessed using electrochemical impedance spectroscopy and cross-cut tests, respectively. Increasing the concentration of silica nanoparticles to 10 wt.% increases contact angles to 167°, although the 4 wt.% coating produces the lowest contact angle hysteresis (3° ± 0.5°) and ice nucleation temperature (−23 °C). The latter coating is then applied to a substrate pretreated with a titanium/cerium-based conversion coating. This prepared surface maintains an ice adhesion of about 15 kPa after 15 icing/de-icing cycles and provides approximately 90 days of surface protection (|Z|lf = 1.6 × 109 Ω·cm2). Notably, the impedance value exceeds that of untreated substrates, underscoring the effectiveness of the titanium/cerium-based conversion coating in enhancing both corrosion resistance and coating adhesion to the substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] Soft materials are promising candidates for designing passive de-icing systems. It is unclear whether low adhesion on soft surfaces is due to elasticity or lubrication, and how these properties affect the ice detachment mechanism. This study presents a systematic analysis of ice adhesion on soft materials with different lubricant content to better understand the underpinning interaction. The wetting and mechanical properties of soft polydimethylsiloxane with different lubricant content were thoroughly characterized by contact angle, AFM indentation, and rheology measurements. The collected information was used to understand the relationship with the ice adhesion results, obtained by using different ice block sizes. Three different de-icing mechanisms were identified: (i) single detachment occurs when small ice blocks are considered, and the ice completely detaches in a single event. In the case of larger ice blocks, the reattachment of the ice block is promoted by either: (ii) stick–slip or, (iii) interfacial slippage, depending on the lubricant content. It was confirmed that the ice adhesion strength not only depends on material properties but also on experimental conditions, such as the ice dimensions. Moreover, differently than on hard surfaces, where wetting primarily determines the icephobic performance, also elasticity and lubrication should be considered on soft surfaces. [ABSTRACT FROM AUTHOR]

Elastomers are intriguing materials for many applications, one of these being icephobic coatings. Elastic modulus and work of adhesion are the key parameters coming into play in ice detachment mechanisms, and can be related to hardness and wettability. Polydimethylsiloxane (PDMS) is widely used for anti-ice applications; however, not many works deal with the correlation between cross-linking grade, curing treatments, and icephobicity. This study focuses on PDMS (Sylgard184®) coatings, encompassing four different pre-polymer to cross-linking agent (A:B) ratios ranging from 5:1 to 30:1, and nine curing treatments. The results indicate that increasing the A:B ratio enhances hydrophobicity, softness, and icephobicity, assessed through shear stress measurements. Curing treatments primarily affect hardness and icephobicity, with longer heat treatments resulting in higher hardness and ice adhesion. All samples exhibit promising performances in lowering shear stress values, up to seven times in respect to the uncoated reference for 30:1 ratio. Additionally, a durability assessment is conducted on samples exposed to stress tests in the climatic chamber. A slight deterioration in hydrophobicity across all samples is observed and, notably, a significant hardness increase, around 13%, is experienced for the 5:1 ratio only. The samples also demonstrate an overall robust icephobicity after stress tests, and, for the 30:1 ratio, an average shear stress value four times lower than the reference is maintained. In this work, we highlight the importance of the fine-tuning of the precursors ratio and thermal treatments on the PDMS properties and durability. [ABSTRACT FROM AUTHOR]

Despite the significant interest of researchers, icing of aircraft, vehicles, ships, and equipment of offshore oil structures remains to be an urgent problem. This paper considers the factors that promote a decrease in the strength of the contact between ice and surfaces under an applied shear load. The main attention is focused on studying the influence of the rate of shear loading on the fracture of the interfacial contact between ice and superhydrophobic coatings. The strength of the adhesive contact under the conditions of controlled variations in the applied load is measured using a technique based on the detachment of ice from a surface under the influence of centrifugal force. The study is carried out for large ensembles of samples in the temperature range from −5 to −20°C, thereby making it possible to evaluate the influence of the quasi-liquid layer and the Rehbinder effect on a decrease in the shear adhesive strength. The results obtained indicate that the contact between ice and a superhydrophobic coating is fractured through a mixed viscous–brittle mechanism. In this case, a decrease in temperature or an increase in the loading rate causes a transition from the viscous to the brittle fracture. These results indicate a potential acceleration of ice shedding with an increase in the growth rate of the shear stress. [ABSTRACT FROM AUTHOR]

Ice accumulation and proliferation adversely affect the activities of various residential, commercial, and polar research stations. Although significant efforts are devoted to preventing ice adhesion to various surfaces by developing various anti‐icing coatings, it is still necessary to enhance overall performance and durability. Herein, a facile approach is proposed for fabricating an icephobic coating on an aluminum 6061 (Al) substrate, by coating a poly(dimethylsiloxane) (PDMS)/ poly(tetrafluoroethylene) (PTFE) composite through a spin‐coating method, followed by sprinkling of SiO2 nanoparticles (NPs). Crosslinker/binder‐free adhesion between PDMS and PTFE is achieved by utilizing secondary‐induced electrostatic dipole‐dipole interactions, these interactions are supported by density functional theory (DFT) calculations as well as structural studies. Moreover, the controlled addition of PTFE powder to PDMS improves the water‐repellency, mechanical strength, and surface roughness of the coating. The self‐formation of the superhydrophobic state of the PDMS/PTFE composite is achieved by sprinkling SiO2 NPs. The sprinkled SiO2 NPs are protected by the PDMS/PTFE composite, which serves as a stress concentrator to achieve low ice adhesion. Furthermore, freezing at low temperatures can be delayed by controlling the heat flow rate, interfacial contact area, and surface texture. This indicates the feasibility of the proposed method for various promising anti‐icing applications. [ABSTRACT FROM AUTHOR]

Unpredictable ice accretion and accumulation phenomena could lead to serious problems and even disastrous accidents. Applying icephobic coatings onto the engineering surfaces could be an effective ice protection method. The icephobicity could be mainly affected by several material strategies, such as wettability, surface topography and surface toughness, etc. Herein, several topographical surfaces (Ni–Cu–P coatings prepared on 304 stainless steel using electroless deposition) are critically investigated to understand the role of surface topography in affecting icephobic performances, including anti‐icing and deicing aspects. The freezing delay tests show that rougher surfaces contribute to longer icing delay in anti‐icing. The ice adhesion strength results indicate that rougher surfaces lead to a more mechanical interlock ice and increase the ice adhesion strength between the ice–solid interfaces. The electrothermal deicing tests indicate that the rough voids introduce large thermal resistance and impede heat conduction, resulting in the increase in detachment duration and energy input in deicing. The rough asperity could introduce air pockets at the surface interfaces, which leads to the difficulty of droplet phase transition. The rough structure also increases the mechanical interlock as well as the thermal resistance and impedes the heat conduction, which deteriorates the deicing ability. [ABSTRACT FROM AUTHOR]

This study examines the efficacy of icephobic polyurethane nanocomposite coatings in mitigating corrosion on an aluminum substrate. A titanium-based conversion coating is applied to modify the substrate, and the research focuses on optimizing the dual functionalities of icephobicity and anticorrosion within the polyurethane coatings while ensuring strong substrate adhesion. The coatings are formulated using fluoropolyol, isocyanate, and silica nanoparticles treated with polydimethylsiloxane. Surface properties are analyzed using contact angles, contact angle hysteresis measurements, and atomic force microscopy, and the coatings’ icephobicity is evaluated through differential scanning calorimetry, freezing time delay, ice adhesion under impact and non-impact conditions, and ice accretion tests. The corrosion resistance and adhesive strength of the coatings are assessed using electrochemical impedance spectroscopy and cross-cut tests, respectively. Increasing the concentration of silica nanoparticles to 10 wt.% increases contact angles to 167°, although the 4 wt.% coating produces the lowest contact angle hysteresis (3° ± 0.5°) and ice nucleation temperature (−23 °C). The latter coating is then applied to a substrate pretreated with a titanium/cerium-based conversion coating. This prepared surface maintains an ice adhesion of about 15 kPa after 15 icing/de-icing cycles and provides approximately 90 days of surface protection (|Z|lf = 1.6 × 109 Ω·cm2). Notably, the impedance value exceeds that of untreated substrates, underscoring the effectiveness of the titanium/cerium-based conversion coating in enhancing both corrosion resistance and coating adhesion to the substrate.

Abstract Ice accumulation and proliferation adversely affect the activities of various residential, commercial, and polar research stations. Although significant efforts are devoted to preventing ice adhesion to various surfaces by developing various anti‐icing coatings, it is still necessary to enhance overall performance and durability. Herein, a facile approach is proposed for fabricating an icephobic coating on an aluminum 6061 (Al) substrate, by coating a poly(dimethylsiloxane) (PDMS)/ poly(tetrafluoroethylene) (PTFE) composite through a spin‐coating method, followed by sprinkling of SiO2 nanoparticles (NPs). Crosslinker/binder‐free adhesion between PDMS and PTFE is achieved by utilizing secondary‐induced electrostatic dipole‐dipole interactions, these interactions are supported by density functional theory (DFT) calculations as well as structural studies. Moreover, the controlled addition of PTFE powder to PDMS improves the water‐repellency, mechanical strength, and surface roughness of the coating. The self‐formation of the superhydrophobic state of the PDMS/PTFE composite is achieved by sprinkling SiO2 NPs. The sprinkled SiO2 NPs are protected by the PDMS/PTFE composite, which serves as a stress concentrator to achieve low ice adhesion. Furthermore, freezing at low temperatures can be delayed by controlling the heat flow rate, interfacial contact area, and surface texture. This indicates the feasibility of the proposed method for various promising anti‐icing applications.

This study details the fabrication of an icephobic coating for steel produced using a silicone–epoxy hybrid resin; the coating has good mechanical properties and weathering resistance for outdoor applications. Silicone–epoxy hybrid resins and amino‐functional silane‐curing agents were selected for investigation and applied to steel samples. Wettability, ice adhesion strength, and the mechanical and weathering resistance properties of the developed coatings were assessed using a drop‐shape analyzer, Fourier transform infrared, X‐ray photoelectron spectroscopy, as well as push‐off, tensile, and QUV tests. The possible correlation between ice adhesion strength and Young modulus was also investigated. The best‐performing matrix in terms of mechanical properties and weathering resistance had its surface energy characteristics altered—via two fluorinated silicone additives at various concentrations—to lower ice adhesion strength. For the steel substrates, the optimized additive‐altered surface showed a lower ice adhesion strength (decreasing from 362 to 94 kPa) with an adhesion reduction factor of 10.6. The fabricated coatings can serve as a protective layer for marine harbor infrastructures. [ABSTRACT FROM AUTHOR]

Ice protection techniques have attracted significant interest, notably in aerospace and wind energy applications. However, the current solutions are mostly costly and inconvenient due to energy-intensive and environmental concerns. One of the appealing strategies is the use of passive icephobicity, in the form of coatings, which is induced by means of several material strategies, such as hydrophobicity, surface texturing, surface elasticity, and the physical infusion of ice-depressing liquids, etc. In this review, surface-roughness-related icephobicity is critically discussed to understand the challenges and the role of roughness, especially on superhydrophobic surfaces. Surface roughness as an intrinsic, independent surface property for anti-icing and de-icing performance is also debated, and their interdependence is explained using the related physical mechanisms and thermodynamics of ice nucleation. Furthermore, the role of surface roughness in the case of elastomeric or low-modulus polymeric coatings, which typically instigate an easy release of ice, is examined. In addition to material-centric approaches, the influence of surface roughness in de-icing evaluation is also explored, and a comparative assessment is conducted to understand the testing sensitivity to various surface characteristics. This review exemplifies that surface roughness plays a crucial role in incorporating and maintaining icephobic performance and is intrinsically interlinked with other surface-induced icephobicity strategies, including superhydrophobicity and elastomeric surfaces. Furthermore, the de-icing evaluation methods also appear to be roughness sensitive in a certain range, indicating a dominant role of mechanically interlocked ice. [ABSTRACT FROM AUTHOR]

Recently, the photovoltaic technology has become very popular as a means to produce renewable energy. One of the problems that are still unsolved in this area of the industry is that photovoltaic panels are subject to a significant loss of efficiency due to the accumulation of dust and dirt. In addition, during the winter season, the accumulation of snow and ice also reduces or stops the energy production. The current methods of dealing with this problem are inefficient and pollute the environment. One way with high potential to prevent the build-up of dirt and ice is to use transparent coatings with self-cleaning and icephobic properties. In this work, the chemical modification of an epoxy–silicone hybrid resin using dually functionalized polysiloxanes was carried out. The icephobic properties (ice adhesion and freezing delay time of water droplets), hydrophobic properties (water contact angle, contact angle hysteresis, and roll-off angle), average surface roughness, and optical properties were characterized. It can be concluded that the performed chemical modification resulted in a significant improvement of the icephobic properties of the investigated coatings: ice adhesion decreased by 69%, and the freezing delay time increased by 17 times compared to those of the unmodified sample. The polysiloxanes also caused a significant reduction in the contact angle hysteresis and roll-off angle. The chemical modifications did not negatively affect the optical properties of the coatings, which is a key requirement for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Ice formation affects the performance of many industrial components, including aircraft wings, spacecraft, and power transmission cables. In particular, ice build-up on airplane components increases drag and fuel consumption. A large number of studies have been carried out to reduce ice adhesion by developing passive methods such as icephobic coatings and active ice removal approaches such as mechanical vibrations or chemical-based solutions. Despite remarkable recent breakthroughs in the fabrication of icephobic coatings, passive ice removal solutions require higher durability to resist cyclical mechanical ice detachment treatments. Functionalized TiO2 coatings, applied using the suspension plasma spray (SPS) technique, have been shown to be robust and to have dual-scale characteristics in an ice accretion analysis. In this study, the icephobicity and mechanical durability of a novel duplex coating consisting of polytetrafluoroethylene (PTFE) solid lubricant films on TiO2-coated substrates were evaluated. Notably, various amounts of PTFE were applied on top of the TiO2 coating to identify the ideal quantity required to obtain optimal icephobic properties. Ice was generated in an icing wind tunnel, and the amount of accreted ice was evaluated to assess the anti-icing properties. Wettability parameters, including static water contact angle and contact angle hysteresis, were measured to determine the water mobility and surface energy. Ice shear adhesion to the PTFE-TiO2 duplex coating was measured using a custom-built test rig. The mechanical durability was assessed by measuring the ice shear strength for almost twenty icing–deicing cycles, and after five cycles, the roughness parameters and images taken from the surface of the samples were compared. The combination of PTFE solid lubricant film and TiO2 coating reduced ice adhesion by 70%–90% compared to that of a bare aluminum substrate (reference material). Additionally, the results showed that the application of a uniform layer of PTFE solid lubricant film on dual-scale TiO2 coating significantly reduced ice adhesion and maintained mechanical durability for 25 deicing cycles, making this combination a promising candidate for deicing approaches. [ABSTRACT FROM AUTHOR]

[Display omitted] Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfaces and ice by visualizing these optically inaccessible regions. Frozen droplets with controlled volume were deposited on top of metallic and polymeric substrates with different levels of wettability. Different modes of XCT (3D and 4D) were utilized to obtain information on the internal and interfacial structure of the ice/surface system. The results were supplemented by conventional surface analysis techniques, including optical profilometry and contact angle measurements. Using XCT on ice/surface systems, the 3D and 4D (imaging with temporal resolution) structural information can be visualized. From these datasets, qualitative and quantitative results were obtained, not only for characterizing the interface but also for analyzing the entire droplet/surface system, e.g., measurement of porosity size, shape, and location. These results highlight the potential of XCT in the characterization of both droplets and substrates and proves that the technique can aid to develop hydrophobic surfaces for use as icephobic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A universal approach was proposed to introduce microporous metallic scaffolds in the LIS construction to prompt the potential of LIS for ice mitigation. • The new LIS construction offered a solution for the rapid oil depletion by restraining the deformation of the matrix material. • The multiphase icephobic layer structures have demonstrated good icephobicity and significantly improved durability. Hypothesis: Ice accretion on component surfaces often causes severe impacts or accidents. Liquid-infused surfaces (LIS) have drawn much attention as icephobic materials for ice mitigation in recent years due to their outstanding icephobicity. However, the durability of LIS constructions remains a big challenge, including mechanical vulnerability and rapid depletion of lubricants. The practical applications of LIS materials are significantly restrained, and the full potential of LIS for ice prevention has yet to be demonstrated. Experiments: A universal approach was proposed to introduce microporous metallic scaffolds in the LIS construction to increase the applicability and durability, and to prompt the potential of LIS for ice mitigation. Microporous Ni scaffolds were chosen to integrate with polydimethylsiloxane modified by silicone oil addition. Findings: The new LIS construction demonstrated significantly improved durability in icing/de-icing cyclic test, and it also offered a solution for the rapid oil depletion by restraining the deformation of the matrix material. Low ice adhesion strength could be maintained via a micro-crack initiation mechanism. The results indicated that the multi-phase LIS construction consisting of microporous Ni scaffolds effectively addressed the shackles of the icephobicity deterioration of LIS materials, confirming a new design strategy for the R&D of icephobic surfaces. [ABSTRACT FROM AUTHOR]

Superhydrophobic surfaces fabricated by grafting 1H,1H,2H,2H-heptadecafluorodecyl trimethoxysilane (FD-TMS) and polydimethylsiloxane triethoxysilane (PDMS-TES) onto a nano-micro hierarchical aluminum (Al) surface are considered to possess substantial anti-icing functionality, with delayed freezing and low ice-adhesion strength (IAS). Verifying the impacts of PDMS and the synergism of PDMS and FD on the anti-icing performance is the goal of this study. Roughness, one of the prerequisites for superhydrophobicity, was obtained by etching Al substrates in aqueous HCl, followed by immersion in boiling water. FD-TMS and PDMS-TES were then coated on the rough Al substrates layer by layer; a congener coated with a single layer was also prepared for comparison. The FD-PDMS1.92 (1.92 wt.%) coating, in which FD-TMS and PDMS-TES were used as primary and secondary coating materials, respectively, exhibited superior icephobicity, with the lowest IAS of 28 kPa under extremely condensing weather conditions (−20 °C and 70% relative humidity, RH) and the longest freezing delay time of 230 min (at −18 °C). These features are attributed to the incorporation of a dense coating layer with a low-surface-tension FD and the high mobility of PDMS, which lowered the contact area and interaction between the ice and substrate. The substrate coated with FD-PDMS1.92 exhibited improved durability with an IAS of 63 kPa after 40 icing/melting cycles, which is far less than that achieved with the FD single-layer coating. [ABSTRACT FROM AUTHOR]

Anti-icing coatings have provided a very good alternative to current, uneconomic, active deicing methods, and their use would bring a number of significant benefits to many industries, such as aviation and energy. Some of the most promising icephobic surfaces are those with hydrophobic properties. However, the relationship between hydrophobicity and low ice adhesion is not yet clearly defined. In this work, chemical modification of an epoxy gelcoat with chemical modifiers from the group of double organofunctionalized polysiloxanes (generally called multifunctionalized organosilicon compounds (MFSCs)) was applied. The anti-icing properties of manufactured coatings were determined by means of measurements of shear strength between the ice layer and the modified surface, conducted using a tensile machine. In the work, tests were also performed on the roughness, wettability, and durability of the properties in an aging chamber. It was found that the performed modifications of the coating's chemical composition by the addition of polysiloxanes enabled us to reduce ice adhesion by 51% and to increase the water contact angle by 14% in comparison to the neat gelcoat. A reduction in ice adhesion was also observed with the increasing water contact angle and with decreasing surface roughness. In addition, only one modification recorded an increase in ice adhesion after exposure in the aging chamber. [ABSTRACT FROM AUTHOR]

• Six supercoolers with icephobic coatings were tested for ice slurry generators. • Three different chemical families were assessed at different mass flow rates. • Coated supercoolers achieve average supercooling degrees in the range of 3 K to 4 K. • Best icephobic coatings increase the supercooling degree by 30 % to 40 %. A supercooler is a heat exchanger that allows to supercool water avoiding ice nucleation on the heat exchanger surface. In this paper, six supercoolers with icephobic coatings were tested for supercooling ice slurry generators. As reference, a supercooler without any coating was used. For coating comparison, three different chemical families were tested at different mass flow rates. Experiments of coated heat exchangers show average supercooling degrees in the range of 3K to 4K. All icephobic coatings improved the supercooling degree respect to the reference non coated case by 7% to 44% at 1000 kg h − 1 mass flow rate with supercooling powers up to 5 kW. For a mass flow rate of 2000 kg h − 1 a supercooling power of about 6kW has been reached for five coatings at a temperature of − 2.5 ∘ C and hold constant for a time span of 3h. Some coatings could reach lower temperatures at this mass flow, but the experimental setup was limited to this supercooling power. The two coatings performing best in the heat exchanger tests were both from the family class hybrid organic-inorganic silane sol-gel with improvements in the degree of supercooling respect to the reference uncoated heat exchanger of 30% to 40%. The supercooling degrees achieved in the present work are up to two times larger compared to results published in scientific journals until this date using industrially relevant heat exchangers. [ABSTRACT FROM AUTHOR]

Nature inspires the artificial morphology regulation of surface structures that is highly preferred for applications such as wettability tuning. In comparison to smart responsive surfaces determined by the progress in material science, microfluidics has provided a material-independent pathway toward programmable surface structures; however, it strongly relies on complex and cumbersome system architecture, thus limiting the number of programmable structures. Inspired by integrated circuits, we use microfluidics and low-surface-energy coating to develop a programmable superrepellent surface, enabling multi-unit morphology regulation with minimal control components. For pedagogical purposes, we realize the programmable control of 8 × 8 basic structures by 6 control components, affording the preferred morphology to tune wettability. As an extension, the anti-icing and de-icing capabilities of the surface at low temperature are also demonstrated. Moreover, for droplet manipulation, the surface can be freely programmed to create elaborated morphological patterns for directional droplet bouncing and rolling, especially with a gradient pattern for stepless control and a pattern splice for long-distance transport. The integrated-circuit-like programmable superrepellent surface provides new insights into wettability tuning, icephobicity, and droplet manipulation. [Display omitted] • A material-independent pathway toward programmable morphology regulation for wetting surfaces is provided. • An integrated-circuit-like surface is developed to enable multi-unit morphology regulation with minimal control components. • Wettability tuning and icephobicity of the surface are demonstrated. • The surface shows stepless control and long-distance transport in droplet manipulation. [ABSTRACT FROM AUTHOR]

In light of the escalating demands for ice protection related applications in diverse fields, including wind energy, power lines and aerospace, there is a notable surge in interest and attention toward the icephobic materials. The increased focus reflects a growing recognition of the crucial role of materials that demonstrate superior resistance to icing phenomenon. However, the intricate correlation between material wettability and icephobicity remains inadequately elucidated. This study aimed to investigate the factors that influence the relationship between icephobicity and different wetting states. The impact of varying surface topographies was examined within the scope of this investigation. A comprehensive analysis was conducted to evaluate the anti-icing and de-icing performances of the surfaces, encompassing anti-frost, ice shear adhesion strength and electro-thermal heating de-icing aspects. Furthermore, the static and dynamic wettability, along with surface free energy measurements, were also performed to enhance the comprehension of icephobicity variation. The detailed water condensation on various surfaces was meticulously observed using environmental scanning electron microscopy (ESEM). The findings elucidated a strong correlation between the icing behaviour and surface topography. It was observed that the surface topography acted as an amplifier, intensifying the deteriorating effect in icephobicity: the formed glaze per unit area exhibited a significant increase with rough asperities; the ice adhesion strength suffered an obvious increase with rough surface and lower hydrophobicity as well as the prolonged ice detachment and overall energy consumption. Therefore, careful consideration should be devoted to the tailoring of surface morphology and wettability when designing and fabricating icephobic surfaces. • Both evolving wetting features and surface morphology significantly affect the icephobic performance. • ESEM observation, surface energy and XPS analysis reveal the contribution of surface adsorption on icephobicity alteration. • Surface topography acts as an amplifier, the increase in roughness could intensify the declining trend in icephobicity. [ABSTRACT FROM AUTHOR]

Superhydrophobicity and icephobicity are governed by surface chemistry and surface structure. These two features signify a potential advance in surface engineering and have recently garnered significant attention from the research community. This review aims to simulate further research in the development of superhydrophobic and icephobic surfaces in order to achieve their wide-spread adoption in practical applications. The review begins by establishing the fundamentals of the wetting phenomenon and wettability parameters. This is followed by the recent advances in modeling and simulations of the response of superhydrophobic surfaces to static and dynamic droplets contact and impingement, respectively. In view of their versatility and multifunctionality, a special attention is given to the development of these surfaces using nanocomposites. Furthermore, the review considers advances in icephobicity, its comprehensive characterization and its relation to superhydrophobicity. The review also includes the importance of the use of superhydrophobic surface to combat viral and bacterial contamination that exist in fomites. [ABSTRACT FROM AUTHOR]

Recently, the photovoltaic technology has become very popular as a means to produce renewable energy. One of the problems that are still unsolved in this area of the industry is that photovoltaic panels are subject to a significant loss of efficiency due to the accumulation of dust and dirt. In addition, during the winter season, the accumulation of snow and ice also reduces or stops the energy production. The current methods of dealing with this problem are inefficient and pollute the environment. One way with high potential to prevent the build-up of dirt and ice is to use transparent coatings with self-cleaning and icephobic properties. In this work, the chemical modification of an epoxy–silicone hybrid resin using dually functionalized polysiloxanes was carried out. The icephobic properties (ice adhesion and freezing delay time of water droplets), hydrophobic properties (water contact angle, contact angle hysteresis, and roll-off angle), average surface roughness, and optical properties were characterized. It can be concluded that the performed chemical modification resulted in a significant improvement of the icephobic properties of the investigated coatings: ice adhesion decreased by 69%, and the freezing delay time increased by 17 times compared to those of the unmodified sample. The polysiloxanes also caused a significant reduction in the contact angle hysteresis and roll-off angle. The chemical modifications did not negatively affect the optical properties of the coatings, which is a key requirement for photovoltaic applications.

Ice protection techniques have attracted significant interest, notably in aerospace and wind energy applications. However, the current solutions are mostly costly and inconvenient due to energy-intensive and environmental concerns. One of the appealing strategies is the use of passive icephobicity, in the form of coatings, which is induced by means of several material strategies, such as hydrophobicity, surface texturing, surface elasticity, and the physical infusion of ice-depressing liquids, etc. In this review, surface-roughness-related icephobicity is critically discussed to understand the challenges and the role of roughness, especially on superhydrophobic surfaces. Surface roughness as an intrinsic, independent surface property for anti-icing and de-icing performance is also debated, and their interdependence is explained using the related physical mechanisms and thermodynamics of ice nucleation. Furthermore, the role of surface roughness in the case of elastomeric or low-modulus polymeric coatings, which typically instigate an easy release of ice, is examined. In addition to material-centric approaches, the influence of surface roughness in de-icing evaluation is also explored, and a comparative assessment is conducted to understand the testing sensitivity to various surface characteristics. This review exemplifies that surface roughness plays a crucial role in incorporating and maintaining icephobic performance and is intrinsically interlinked with other surface-induced icephobicity strategies, including superhydrophobicity and elastomeric surfaces. Furthermore, the de-icing evaluation methods also appear to be roughness sensitive in a certain range, indicating a dominant role of mechanically interlocked ice.

Fabrication of icephobic and hydrophobic coating is a challenge of recent researches. In this article, we study the icephobicity and hydrophobicity of a nanocomposite from silica-titanium oxide nanoparticles in the polyvinylidene-fluoride matrix. The surface energy of the prepared nanocomposites was tested by measuring the contact angle of different liquid droplets. Results show that the wettability is dependent on the concentration of nanoparticles, and the minimum surface energy of the prepared surface is 22.6 mJ m - 2 . In addition, icephobicity tests for cooled substrate show that the contact angle of the water droplet reduces to about 115° after freezing. Moreover, the icing test in the freezer shows a decrease in humidity freezing on the surface down to 25 g m–2. Finally, stability tests in harsh environmental conditions such as UV radiation and heating indicate that the surface is substantially stable. [ABSTRACT FROM AUTHOR]

In recent years, to progress towards carbon emissions reduction, photovoltaic technology has become one of the most significant methods of generating electricity using renewable sources. However, the accumulation of ice and snow during the winter season affects the decrease in the power generation efficiency of photovoltaic modules. As a promising solution, coatings that exhibit anti-icing properties can be used. To date, no efficient ice-phobic coating has been developed for use on photovoltaic panels. In this paper development of transparent silicone-epoxy coatings modified with bi- and tri-functionalized octaspherosilicates was presented. The used organosilicone-based modifiers reveal both types of functional groups: one increases the surface properties and the second compatibility with the polymer matrix. The icephobic properties were discussed by determining an ice adhesion (IA) and a freezing delay time of water droplets (FDT). The coating exhibiting the highest anti-icing performance achieved the IA of 102 kPa and the FDT of 210 min, a 43 % reduction and a 70 times increase in value compared to the unmodified coating, respectively. The performed study included also the characterization of hydrophobic properties: water contact angle (WCA) at room temperature and below 0°C, contact angle hysteresis(CAH), and roll-off angle (RoA) as well as surface roughness and coatings thickness. In addition, the correlations between them and ice adhesion/freezing delay time were determined. It was found that roughness as well as dynamic parameters of the wettability of CAH and RoA have a significant effect on the obtained IA values. Moreover, the developed coatings can be potentially applied to photovoltaic panels, since the conducted modification did not affect the optical properties of the investigated coatings. [Display omitted] [ABSTRACT FROM AUTHOR]

We provide a conceptual framework to correctly measure both ice adhesion strength and interfacial toughness, using a simple push test method, for a complete and comprehensive assessment of ice adhesion on surfaces. [Display omitted] • The ice-substrate fracture mechanism can be stress- or toughness-dominated. • A novel conceptual framework for ice adhesion measurements is provided. • Interfacial toughness measurement procedure based on simple push test is proposed. The interest in the development of icephobic surfaces has pushed towards the definition of standardized processes and parameters to assess ice adhesion, with the ambition of identifying an equivalent method to contact angle measurements used to assess wetting properties. Although most studies focus on the average ice adhesion strength, measured as the force per unit area required to detach ice, much less attention is paid to interfacial toughness, perhaps as its measurement is challenging. In this article, we provide a conceptual framework to correctly measure both ice adhesion strength and interfacial toughness, even using a simple push test method, laying the ground for a complete and comprehensive assessment of surface icephobicity. [ABSTRACT FROM AUTHOR]

Spontaneous removal of liquid, solidifying liquid and solid forms of matter from surfaces, is of significant importance in nature and technology, where it finds applications ranging from self-cleaning to icephobicity and to condensation systems. However, it is a great challenge to understand fundamentally the complex interaction of rapidly solidifying, typically supercooled, droplets with surfaces, and to harvest benefit from it for the design of intrinsically icephobic materials. Here we report and explain an ice removal mechanism that manifests itself simultaneously with freezing, driving gradual self-dislodging of droplets cooled via evaporation and sublimation (low environmental pressure) or convection (atmospheric pressure) from substrates. The key to successful self-dislodging is that the freezing at the droplet free surface and the droplet contact area with the substrate do not occur simultaneously: The frozen phase boundary moves inward from the droplet free surface toward the droplet-substrate interface, which remains liquid throughout most of the process and freezes last. We observe experimentally, and validate theoretically, that the inward motion of the phase boundary near the substrate drives a gradual reduction in droplet-substrate contact. Concurrently, the droplet lifts from the substrate due to its incompressibility, density differences, and the asymmetric freezing dynamics with inward solidification causing not fully frozen mass to be displaced toward the unsolidified droplet-substrate interface. Depending on surface topography and wetting conditions, we find that this can lead to full dislodging of the ice droplet from a variety of engineered substrates, rendering the latter ice-free.

Superhydrophobic surfaces fabricated by grafting 1H,1H,2H,2H-heptadecafluorodecyl trimethoxysilane (FD-TMS) and polydimethylsiloxane triethoxysilane (PDMS-TES) onto a nano-micro hierarchical aluminum (Al) surface are considered to possess substantial anti-icing functionality, with delayed freezing and low ice-adhesion strength (IAS). Verifying the impacts of PDMS and the synergism of PDMS and FD on the anti-icing performance is the goal of this study. Roughness, one of the prerequisites for superhydrophobicity, was obtained by etching Al substrates in aqueous HCl, followed by immersion in boiling water. FD-TMS and PDMS-TES were then coated on the rough Al substrates layer by layer; a congener coated with a single layer was also prepared for comparison. The FD-PDMS1.92 (1.92 wt.%) coating, in which FD-TMS and PDMS-TES were used as primary and secondary coating materials, respectively, exhibited superior icephobicity, with the lowest IAS of 28 kPa under extremely condensing weather conditions (−20 °C and 70% relative humidity, RH) and the longest freezing delay time of 230 min (at −18 °C). These features are attributed to the incorporation of a dense coating layer with a low-surface-tension FD and the high mobility of PDMS, which lowered the contact area and interaction between the ice and substrate. The substrate coated with FD-PDMS1.92 exhibited improved durability with an IAS of 63 kPa after 40 icing/melting cycles, which is far less than that achieved with the FD single-layer coating.

Icing can jeopardize local infrastructure, hinder field operation, destroy vessel superstructures, and threaten life and property safety in the Arctic and other cold offshore and marine environments. Research on ice protection (both anti-icing and de-icing) technologies is critical to equipment, structures, and personnel in these environments. This review systematically evaluates a wide range of ice protection techniques divided into three main categories, i.e., active, passive, and hybrid ice protection techniques. Active anti-icing/de-icing technologies include mechanical, thermal, or chemical methods, requiring an additional energy source to prevent ice formation or remove accumulated ice from the target surfaces. Passive anti-icing/de-icing techniques can prevent ice accumulation or reduce ice adhesion without external energy sources; they create and maintain the icephobic properties of the target surfaces. Excessive energy consumption is a major technical limitation of active ice protection technologies. On the other hand, it is challenging for any passive technology to meet the long-term ice protection requirements in the Arctic or different cold offshore/marine environments. A combination of two or more active and passive ice protection methods, i.e., a hybrid approach, seems promising and can be applied in various situations according to the specific requirements of different vessels, offshore structures, and equipment. [ABSTRACT FROM AUTHOR]

Anti-icing coatings have provided a very good alternative to current, uneconomic, active deicing methods, and their use would bring a number of significant benefits to many industries, such as aviation and energy. Some of the most promising icephobic surfaces are those with hydrophobic properties. However, the relationship between hydrophobicity and low ice adhesion is not yet clearly defined. In this work, chemical modification of an epoxy gelcoat with chemical modifiers from the group of double organofunctionalized polysiloxanes (generally called multifunctionalized organosilicon compounds (MFSCs)) was applied. The anti-icing properties of manufactured coatings were determined by means of measurements of shear strength between the ice layer and the modified surface, conducted using a tensile machine. In the work, tests were also performed on the roughness, wettability, and durability of the properties in an aging chamber. It was found that the performed modifications of the coating’s chemical composition by the addition of polysiloxanes enabled us to reduce ice adhesion by 51% and to increase the water contact angle by 14% in comparison to the neat gelcoat. A reduction in ice adhesion was also observed with the increasing water contact angle and with decreasing surface roughness. In addition, only one modification recorded an increase in ice adhesion after exposure in the aging chamber.

Retarding and preventing ice/frost formation have increasing importance in aerospace applications because of widespread energy and safety concerns. In this study, multiwalled carbon nanotube–polydimethylsiloxane (MWCNT/PDMS) nanocomposites were fabricated via mechanical stirring and three-roll grinding. By imitating the microstructures of lotus leaves, various biomimetic nanocomposites were prepared by etching micropillar arrays on MWCNT/PDMS nanocomposites. These biomimetic nanocomposites possess superior flexibility, electrical conductivity, hydrophobicity, and icephobicity. Effects of the micropillar height on the wettability, freezing process of water droplets, ice/frost formation, and ice adhesion strength were characterized; influences of temperature on the wettability and strength of ice adhesion and feasibility of electrothermal deicing were investigated. The surface wettability, freezing process of water droplets, ice/frost formation, and ice adhesion strength in the Cassie state are independent of the micropillar height. However, compared to flat surfaces, the adhesion strength of ice increases, and formation of ice/frost decreases because of the presence of surface micropillars. At the same micropillar height, an increase in temperature decreases the contact angle and ice adhesion strength. The results indicate that the surface microstructure designability and flexible temperature-controllability of biomimetic nanocomposites have great potential for use in aerospace (anti-/deicing) applications. [ABSTRACT FROM AUTHOR]

The build-up of ice on critical infrastructure could cause severe disruptions and substantial economic consequences. The application of ice-repellent surfaces has been identified as a promising approach to tackle and mitigate the problem. The main challenge is to ensure they can endure harsh environmental conditions and maintain long-term mechanical durability. This study presents an innovative design concept that incorporates phase change liquids with Ni scaffolds and polydimethylsiloxane (PDMS) in a multi-phase ice-repellent construction. Incorporating phase change liquids within the oil-infused surface construction facilitates the absorption and subsequent release of heat during the icing process. The supercooled droplets took significantly longer (7–8 times) to ice on the sample surfaces compared to aluminum alloy, attributed to the solidification of phase change liquids at low temperatures, resulting in decreased oil depletion during de-icing. Furthermore, the durability enhancement effect was validated by the weight maintenance ratio of samples, which remained almost unchanged after undergoing 50 cycles of icing/de-icing tests, providing a practical solution for addressing concerns on oil depletion in prolonged service conditions. • A novel icephobic structure using Ni scaffolds, PDMS infused with phase change oil and aerogel powder was developed. • The inclusion of oil extends the ice formation and reduces oil depletion effectively, enhancing the icephobicity stability. • The infusion of oil with phase change temperature ~ 0 °C into multiphase structure poses beneficial impact on icephobicity. [ABSTRACT FROM AUTHOR]

Anti-icing coatings reduce the freezing onset temperature for water by changing the chemical and physical environment at the water-substrate interface to prevent ice nucleation and growth. Graphene oxide has several attributes that make it attractive as an anti-icing coating and it has been theoretically predicted that graphene oxide has a lower freezing onset temperature than pristine graphene. Here, we test this hypothesis using carefully prepared, well-characterized graphene oxide substrates. We compare the water contact angle for graphene and graphene oxide coatings, both prepared on iridium(111) surfaces. The results show both materials to be transparent to wetting, but indicate a lower freezing onset temperature for graphene oxide than for pristine graphene. The measured water contact angles are dominated by the properties of the underlying Ir(111) substrate while the freezing onset temperature is dictated by the functional groups present on the graphene basal plane. We suggest that the lowering of the freezing onset temperature is caused by the formation of a viscous water layer on the surface. Scanning tunneling microscopy and x-ray photoelectron spectroscopy data are used to evaluate the robustness of the coating material and suggest ways to improve the long-term performance, namely by advancing strategies to avoid water intercalation. Image 1 • Graphene and graphene oxide on Ir(111) are transparent to wetting but not to icing. • Graphene oxide on Ir(111) have a lower freezing onset temperature than pristine graphene on Ir(111). • Wettability and freezing onset temperature of graphene and graphene oxide on Ir(111) are stable over days. • STM and XPS analysis show that the chemical environment on the graphene surfaces change after wetting and icing experiment. [ABSTRACT FROM AUTHOR]

Icephobic coatings interest various industries facing icing problems. However, their durability represents a current limitation in real applications. Therefore, understanding the degradation of coatings under various environmental stresses is necessary for further coating development. Here, lubricated icephobic coatings were fabricated using a flame spray method with hybrid feedstock injection. Low-density polyethylene represented the main coating component. Two additives, namely fully hydrogenated cottonseed oil and paraffinic wax, were added to the coating structure to enhance coating icephobicity. Coating properties were characterised, including topography, surface roughness, thermal properties, wettability, and icephobicity. Moreover, their performance was investigated under various environmental stresses, such as repeated icing/deicing cycles, immersion in corrosive media, and exposure to ultraviolet (UV) irradiation. According to the results, all coatings exhibited medium-low ice adhesion, with slightly more stable icephobic behaviour for cottonseed oil-based coatings over the icing/deicing cycles. Surface roughness slightly increased, and wetting performances decreased after the cyclic tests, but chemical changes were not revealed. Moreover, coatings demonstrated good chemical resistance in selected corrosive media, with better performance for paraffin-based coatings. However, a slight decrease in hydrophobicity was detected due to surface structural changes. Finally, paraffin-based coatings showed better resistance under UV irradiation based on carbonyl index and colour change measurements.

Given the role of micro-nanostructures in producing superhydrophobic and icephobic surfaces and the importance of high-quality replication of these micro-nanostructures in direct replication processes, we evaluated the effect of processing parameters on the superhydrophobicity, icephobicity, and replication quality of silicone rubber surfaces created via micro-compression molding. Molding pressure, mold temperature, curing time, and part thickness were selected as the processing parameters to be assessed. We used a response surface methodology to illustrate the optimal values of the selected processing parameters. Molding pressure and part thickness were the main influencing parameters to attain the superhydrophobicity. In a second set of experiments, we assessed the replication quality of silicone rubber surfaces of variable thickness subjected to different molding pressures. Each part thickness had an optimal molding pressure for obtaining the best replication quality. Surfaces having the highest replication quality also demonstrated the longest freezing delay and confirmed their potential use as anti-icing surfaces. Although all developed superhydrophobic surfaces showed icephobicity, the influence of processing parameters affecting ice adhesion was complex. [ABSTRACT FROM AUTHOR]

Ice adhesion tests can be correctly understood only if the appropriate fracture mechanism is identified. Here we reframe the theoretical understanding of ice adhesion mechanisms, to predict the type of detachment mechanism for horizontal push tests. [Display omitted] • Identification of ice-substrate fracture mechanisms is critical for ice adhesion. • The critical shear stress is only meaningful in a stress-dominated fracture regime. • The theoretical understanding of ice adhesion mechanisms is reframed. • Fracture model for detachment mechanism prediction is provided. • Guidelines for the correct interpretation of ice adhesion results are provided. Mitigating icing hazards is of interest for many technological applications. One solution is to employ low ice adhesion coatings, either passively or in combination with active de-icing systems. Nevertheless, comparing different low ice adhesion surfaces can be challenging. Studies generally report the average shear stress, calculated as the ratio of applied force to the ice-substrate contact area; however, the fracture mechanism at the ice-substrate interface is rarely reported. There are two fracture mechanisms that can occur at the interface: stress-dominated and toughness-dominated. Average shear stress is only meaningful when performing adhesion tests in a stress-dominated regime; otherwise, interface stresses are underestimated and misleading. This study presents a new understanding of ice adhesion mechanisms combining experimental and numerical methods, demonstrating how the traditional ice adhesion reporting method can lead to errors up to 400%. Using a simple fracture model, the study shows that the stress-dominated fracture regime in the horizontal push test is favored by smaller ice diameter and greater ice thickness, and is also affected by the load force position. The identification of the two fracture regimes is required for the correct understanding and reproducibility of ice adhesion results, enabling better design and characterization of icephobic coatings and materials. [ABSTRACT FROM AUTHOR]

Industries around the world use active methods, which include thermal, mechanical and chemical approaches, to reduce icing on aerodynamic surfaces such as wind turbines and aircraft. However, they are often inefficient, costly, and pollute the environment. For years, new coatings with anti-icing properties (so-called icephobic coatings) have been developed to either replace or work in tandem with active systems. In this study, coatings were designed based on an epoxy gelcoat commonly used for wind turbines through chemical modification with spherosilicate derivatives. Di- and tri-functional spherosilicates have both groups that increase the degree of hydro-/icephobicity of composites and groups capable of interacting with epoxy resin and amine hardener. The icephobicity of the surface was determined using ice adhesion. The lowest value of this parameter reached a value of 186 kPa, a 30 % reduction compared to the unmodified coating. In addition, the hydrophobicity of the surface was determined (the highest water contact angle was equal to 103°). A correlation was observed, proven in many works, that as the surface roughness increases, the anti-icing properties deteriorate. For individual modifications, it was also shown that hydrophobicity has a positive effect on ice adhesion. The work also examined the surface zeta potential and determined the durability of the properties after 100 icing/deicing cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

Ice accretion and accumulation may cause a severe problem in many disparate fields from aircraft to electrical transmission lines. Super-hydrophobic (SHP) surfaces can have a potential anti-icing application due to their extreme water repellency. However, there is a lack in the characterization of icing behavior of these surfaces. Moreover, durability is a major concern for this kind of coatings. One class of super-hydrophobic surfaces is constituted by hierarchical structures, in which a micrometric roughness is combined with a nanometric roughness and finally covered by a low energy chemical finishing. In the present work, we experimentally investigated how the micrometric roughness of the aluminum alloy surface can influence the hierarchical micro-nanostructure and the consequent hydrophobic and anti-icing properties, especially in terms of durability. Aluminum alloy samples were sandblasted or polished to generate a different micrometric roughness. The following steps to obtain a hierarchical super-hydrophobic structure (nano-roughness and final low energy chemical treatment) were kept constant for all samples. The hydrophobic properties were characterized at room and low temperatures and the anti-icing behavior was measured by shear stress tests. Several repetitions of the shear stress measurement on the same samples and icing- thaw cycles were conducted to study the durability of the coatings. This work describes an easy, fast and economic process to obtain super-hydrophobic materials with durable anti-icing properties, with interesting applications in many industrial fields. • Icephobic aluminum is obtained by roughening, boiling and coating the surfaces. • Different roughness treatments cause different hydrophobic and icephobic properties. • Hydrophobicity at low temperature gives clues of the icephobicity of the samples. • The sandblasted samples have a promisingly durable icephobicity. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the effect of wear on the ice adhesion of elastomeric coatings. Approaches in designing surfaces with lower ice adhesion include imparting hydrophobicity, lubrication, crosslink density reduction or induction of interfacial slippage. For icephobic surfaces to find widespread use, it is imperative that they are durable. In the current work, a suitable plasticizer is used to modify the cross-link density and stiffness of a polyurethane elastomeric coating. The wear behavior of the modified elastomer under two body abrasion is studied in terms of its weight loss and topography evolution. The wear loss varies with the coating stiffness, wherein the elastomer with lower stiffness exhibits higher weight loss. The evolution of surface topography as a function of wear is analyzed in terms of roughness parameters and autocorrelation length, and its effect on the ice adhesion behavior of the coating. The results show that wear initially increases ice adhesion, but adhesion reduces as wear propagates due to the evolution of surface topography. The study shows that, among the samples tested, a 20%–30% plasticizer content produces a good combination of icephobicity and wear resistance. • The wear and ice adhesion behavior of elastomeric icephobic surfaces are analyzed. • The spatial evolution of wear surface and its effect on ice adhesion are reported. • Ice adhesion with roughness and autocorrelation length evolution are reported. • The impact of the onset and progression of wear on ice adhesion is elucidated. [ABSTRACT FROM AUTHOR]

Superhydrophobic micro‐/nanopatterned structures exhibit robust water/ice repellence in harsh environments, which is significant for theoretical study and industrial applications such as cooling in nuclear power, heat transfer, and self‐cleaning for aircraft. However, the reported studies regarding icephobic functional surfaces based on rigid materials have indicated potential dangers in applications, e. g., the roughness topographies are easily ruined in the icing process, which limits further application and study. In this study, polydimethylsiloxane‐based flexible microneedles (FNs) with ZnO nanorods are designed and fabricated and further characterized with robust icephobicity at a temperature of 0 °C. In this system, the flexible microneedles could bend to match the deformation caused by icing from condensed droplets, resulting in protecting the nanorods on its surface, which is significantly promising for durable icephobicity in harsh environments. Robust Icephobicity: A superhydrophobic, self‐cleaning surface made of flexible needles has been designed that is anti‐icing at low temperatures. The flexible microneedles can bend to match the deformation caused by icing, which protects the nanorods and ensures stable performance. [ABSTRACT FROM AUTHOR]