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Ice accumulation leads to improper functioning or even damages to ships, offshore platforms, sports facilities and land buildings in cold climate regions. Although fluorochemicals have demonstrated attractive performance for icephobic applications, their use has been restricted due to health and environmental concerns. Here, we present a facile method to fabricate fluorine-free icephobic coatings with potential applications for outdoor facilities and structures. The coating consists of a silicone-epoxy hybrid resin, polydimethylsiloxane (PDMS) and SiO2 nanoparticles with different sizes. Particularly, the use of different sized (10–20 nm and 200 nm) SiO2 nanoparticles results in excellent icephobicity and mechanical properties. The mechanical properties and durability of the coating were analysed according to respective test standards and compared with other reported icephobic coatings. The durable icephobic potency of the coatings is very promising as a sustainable green solution for various practical anti-icing applications. Agency for Science, Technology and Research (A*STAR) Nanyang Technological University Accepted version Financial support is gratefully acknowledged from Nanyang Technological University (NTU) in form of research student scholarship (RSS), NTU-industry collaborative funding in the form of RCA, and the Agency for Science, Technology and Research (A*STAR) of Singapore in the form of research grant (SERC 1528000048).

Ice accretion is the process by which a layer of ice builds up on solid objects that are exposed to freezing precipitation or supercooled cloud of droplets. In fact, the onset of ice accretion can be sudden and hazardous. This has motivated the development and deployment of icephobic coatings as an effective strategy to prevent or suppress ice accumulation on critical and functional surfaces. Previously, we reported a scalable technique to fabricate durable superhydrophobic coatings using siloxane-modified epoxy nanocomposites. Herein, we extend our earlier research by investigating the potential of using these nanocomposites as candidates for icephobicity. Accordingly, nanocomposites with varied silica nanoparticles’ concentrations were considered in our efforts to modify the surface energy and structure to transform the original superhydrophobic surface into an icephobic surface. Our results indicate that a highly superhydrophobic surface (25 wt% nanocomposite) can be ineffective in combating ice accretion at subfreezing temperatures. In contrast, a nanocomposite with a nanoparticles concentration of 35 wt% was found to (i) facilitate the full rebounding of supercooled droplets, while maintained at −10 °C, (ii) reduce the water nucleation temperature to −12 °C, (iii) delay the freezing process by ∼ 94 s at a temperature of −10 °C, and (iv) reduce the ice adhesion strength to ∼ 230 kPa. This comprehensive assessment of the different aspects of icephobicity was considered essential as it ensures the surface’s effectiveness against the variety of conditions that lead to ice accretion. Moreover, the developed nanocomposite coatings demonstrated excellent adhesion strength as well as consistent wettability and icephobicity after being subjected to numerous icing/thaw cycles. The outcome of our effort offers a great potential for the large-scale adoption of siloxane-modified nanocomposites in applications that require protection against ice accretion.

Sustainable easy removal of accreted ice has been strongly desired worldwide. Passive anti-icing strategies relying on durable surface coatings are highly desired because of their simplicity and low cost compared to the energy-intensive active strategies. The current state-of-the-art anti-icing technologies, such as liquid-infused surfaces, are able to dramatically reduce ice adhesion strength. Nevertheless, severe durability challenges of lubricant depletion and coating damage during the ice removal process hinder their practical applications. Here, we report a quasi-liquid surface that can significantly reduce the ice adhesion strength by reducing the shear modulus of the coating. The quasi-liquid lubrication provided by the highly mobile chains of the flexible polymer changes the sticky ice/solid interface to a non-sticky ice/quasi-liquid interface. Moreover, each molecule chain is chemically bonded on the solid substrate so the entire surface can withstand abrasion in long-term de-icing conditions. The icephobicity on the quasi-liquid coating persists after chemical rinsing while the state-of-the-art liquid-infused surface fails due to lubricant depletion. In addition, we have demonstrated that controlling the shear modulus of an icephobic coating can achieve both small- and large-scale ice removal with the quasi-liquid approach. Such a durable quasi-liquid surface with sustainable ultralow shear strength shows a potential to reduce ice accretion on solar panels, power lines, and vehicles in ice prone regions.

Photothermal anti-icing/deicing is an efficient way to circumvent the problems caused by the formation and accumulation of frost and ice to the people living in cold regions. However, achieving this process on robust materials with high efficiency and long-term stability is always challenging. Herein, we facilely constructed a black and superhydrophobic Al using Laser surface direct writing (LSDW) and thermal evaporation of 1H,1H,2H,2H-perfluorodecyltrichlorosilane for efficient anti-icing/deicing applications. The prepared multifunctional Al surface showed excellent superhydrophobicity with a contact angle of 161.2° and light-harvesting capacity with over 94.5% absorption (>96% in the visible spectral range) mainly based on the surface plasmonic resonance of cactus-like Al micro/nanoparticles. The multifunctional Al exhibited excellent light-induced heating and thermal/cold stability, reduced ice adhesion strength, and self-cleaning through its small sliding angle (approximately 0°). With good photothermal behaviors and superhydrophobicity, the multifunctional Al showed strong anti-icing capacity by inhibiting the nucleation and growth of ice crystals, and rapidly deicing and melting the frost and ice layers at − 30 °C. Fabricating such multifunctional Al provides a feasible method for high-efficient anti-icing/deicing applications relied on the green and renewable solar energy.

A finite difference time domain (FDTD) simulation was adopted to initially illuminate a neglected phenomenon that SiO2 nanospheres in superhydrophobic layer could enhance the light absorption capacity of the layer itself, and of the contiguous photothermal semiconductor simultaneously. Guided by this simulation, a solar thermal coating (STC) composed of superhydrophobic SiO2 nanospheres and CuFeMnO4/PDMS was assembled to achieve highly efficient icephobicity. The accurate tests illustrated the temperature rise originated from the semiconductor layer by photothermal effect and superhydrophobic layer by self-heating effect, which was consistent with the simulation results. Depending on the high photothermal conversion efficiency, the freezing temperature of droplets on STC dropped to −35 °C, the ice adhesion strength decreased from 78.5 kPa to 12.1 kPa and an ice layer was removed within 99 s under the light illumination. Furthermore, STC could be further adopted in a cold natural environment, and deicing in 12 min. The simulation-guided construction of STC provides a new design strategy for icephobic coatings and new insights on energy management analysis in superhydrophobic photothermal composite coating.

Polysiloxane is one of the most favorite polymeric materials used in the emerging field of passive surface icephobicity; This is due to its tailorable softness, hydrophobicity, and relatively high durability. Given the state-of-the-art ice adhesion strength of polysiloxane surfaces has reached a threshold below 1 kPa, a timely survey on the published polysiloxane icephobic surfaces can serve as a valuable reference concerning how far the research field has already progressed and how much potential remains to be exploited for the future development of polymeric icephobic materials. This review categorizes the use of polysiloxane materials for icephobic strategies into three classes according to their surface stiffness. The advantages and shortcomings of each polysiloxane material group are assessed. By scrutinizing the current ice adhesion strength theory, a reference coating thickness is identified, which can be used for optimizing icephobic coating design. A surface icephobicity diagram is also presented, where a lower bound of ice adhesion on a smooth surface is derived, depicting the needs of incorporating different mechanisms to break the theoretical low ice adhesion limit. Finally, the challenges in applying the polysiloxane icephobic materials are discussed, and the possible key research directions are highlighted. 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)