Search

Recent emerging strategies to prepare icephobic coatings have focused on slippery surfaces containing a liquid lubricant with low surface energy, which significantly reduces ice adhesion. In this work, a facile technique was developed for preparation of polysiloxane coatings with efficient and durable icephobicity. Fluorinated polyhedral oligomeric silsesquioxanes (F-POSS-SiH) with different fluorinated groups and Si-H active sites were synthesized via hydrosilylation between fluorinated methacrylates and octakis(dimethylsiloxy) octasilsequioxane. The F-POSS-SiH hybrid compound was subsequently applied as a co-crosslinker in the system of polymethylhydrosiloxane (PMHS) and polymethylvinylsiloxane to create silicone coatings. The low surface energy of fluorinated groups could drive F-POSS-SiH towards the coating surface, leading to a gradient distribution in which F-POSS-SiH was self-assembled on the top surface, while silicone was rich in the bottom layer. Meanwhile, wavy surfaces were generated spontaneously by compressive stress during the coating formation. The wavy microstructure of coatings provided space for the unreacted silicone oil, i.e., low molecular weight PMHS, that could be considered as a liquid lubricant and controlled by the dosage. Therefore, the slippery wavy coatings showed highly icephobic properties with extraordinarily low ice shear strengths at a lowest value of 3.8 ± 1.8 kPa, only 5 percentage of Sylgard 184. Moreover, the coatings remained icephobicity after 15 icing/deicing cycles, demonstrating excellent durability. [ABSTRACT FROM AUTHOR]

The ability of phase change materials (PCMs) to absorb and release large amounts of latent heat has led to great interest in their use in anti-icing applications. Combining PCMs and other passive icephobic strategies such as self-lubricating coatings could enhance anti-icing performance. Here, an icephobic coating is fabricated by impregnating an elastomeric matrix containing PEG-PDMS copolymers with PCM microcapsules. First, a selected mixture of n-dodecane and n-tetradecane is encapsulated within urea–formaldehyde shells using in-situ polymerization. Various concentrations of microcapsules are then added into the self-lubricated PDMS coating and 2.5 wt% of hydroxyl-terminated PEG-PDMS copolymer. Differential scanning calorimetry confirms that the PCM-embedded coating has colder ice nucleation temperatures than the self-lubricating coatings lacking microcapsules. The release of latent heat by the PCMs likely preserves the liquid-like layer for a more extended time and delays ice nucleation. The presence of PCM microcapsules can positively affect self-lubricating characteristics of the matrix containing the PEG-PDMS copolymer to further reducing ice adhesion. The presence of a liquid-like layer lowers ice adhesion strength and decreases ice accumulation on surfaces. These particular properties are further enhanced by the incorporated PCM microcapsules and their ability to release latent heat. Finally, the durability of the fabricated coatings is confirmed after multiple icing/de-icing cycles. Such PCM-impregnated coatings therefore offer potential uses for diverse icephobic applications. [Display omitted] • The synergistic effect of combining different anti-icing strategies can enhance icephobic performance. • Phase change materials (PCMs) release a large amount of energy as latent heat. • The presence of a liquid-like layer lowers ice adhesion strength. • Embedding PCM microcapsules into the PEG-PDMS copolymer–containing matrix enhances anti-icing properties. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Polyhedral oligomeric silsesquioxane (POSS)-containing fluorosilicone multi-block methacrylate copolymers (PDMS- b -(PMAPOSS- b -PFMA) 2 ) were synthesized via RAFT polymerization of methacryloisobutyl POSS (MAPOSS) with hexafluorobutyl methacrylate (HFBMA) or dodecafluoroheptyl methacrylate (DFHMA) as different fluorinated side groups. A macro-RAFT chain transfer agent of polydimethylsiloxane with dithiobenzoate groups at both ends was initially used. Characterizations of surface chemical composition and morphology of the copolymer films suggested that the PDFHMA chains with longer fluorinated side groups, as compared with PHFBMA chains, were easy to migrate onto the surface and the surface roughness was enhanced by introducing PMAPOSS segments. The film of multi-block copolymer PDMS- b -(PMAPOSS- b -PDFHMA) 2 produced a fluorine-rich surface due to the enrichment of fluorinated blocks and exhibited the highest receding contact angle (103.8 ± 0.5°) and lowest water contact angle hysteresis (8.7 ± 1.4°) among all the samples, attributed to the introduction of PMAPOSS segments and the synergistic effect of silicon and fluorine. Measurements of icephobic properties demonstrated that the supercooled water droplet could easily slip away from the tilted PDMS- b -(PMAPOSS- b -PDFHMA) 2 surface (45°) at −20 °C and the ice shear strength tended to decrease from 361 kPa to 264 kPa with incorporation of PMAPOSS blocks in comparison with PDMS- b -(PFMA) 2 . However, it was found that decreasing wettability of the block copolymer film did not have significant effect on reducing the ice shear strength. The prepared POSS-containing fluorosilicone multi-block methacrylate copolymers with good icephobicity can be used as icephobic coating materials potentially. [ABSTRACT FROM AUTHOR]

Engineering icephobic coatings has been a long standing effort to address the challenges caused by ice formation and accumulation in our daily lives and in several industrial applications. Therefore, this review summaries trends in the progress of high performance hydrophobic and superhydrophobic polyurethane (PU) based coatings, their potential to be used as icephobic surfaces, applicability in passive anti-icing and consequent drawbacks/challenges. Meanwhile, numerous industrial coatings are recommended, a wide variety of PU based coatings can be produced from a broad range of diisocyanates, polyols and other additives. This makes it possible to obtain various types of tailored coatings from PUs that can serve many specific applications as top coats in different industries due to their specific properties. PU based coatings offer excellent mechanical strength and durability, toughness, good abrasion resistance, etc. However, owing to the fact that they have a lot of polar groups on the surface, PU based coatings are rather hydrophilic in nature. Therefore, achieving superhydrophobic and icephobic PU based coatings remains an important issue for current research and development. The present review aims to shed light on superhydrophobic and icephobic mechanisms that have been pursued to design PU based coatings. At first, a short introduction of the general overview of PU chemistry is presented, followed by a comprehensive review of the state-of-the-art methods that have been used by several researchers to modify and design superhydrophobic and icephobic PU coatings. Finally, the challenges and urgent issues facing further development in this field are discussed. [Display omitted] • Polyurethane (PU) as a promising candidate to develop durable coatings. • Chemistry and properties of different types of PU components, i.e. polyols and isocyanates • State-of-the-art and advances regarding PUs as superhydrophobic coating • PUs as icephobic coating material and different strategies to achieve passive anti-icing. • Drawbacks and future recommendations for designing durable icephobic coatings [ABSTRACT FROM AUTHOR]

Developing superhydrophobic/icephobic coatings is of significance in limiting ice formation, and is an ideal selection to solve the icing issues faced by daily life and industrial production. Recent investigations are mainly focused on scientific research but not practical application. Here, nanocomposite based superhydrophobic PVDF-HFP/SiO 2 /CNTs coatings were designed and fabricated. Large-area nanocomposite coatings have been fabricated, which are robust and adhesive to many substrates. As-synthesized coatings exhibited exceptional water repellency with a contact angle up to 168° and slide angle lower than 2°. Anti-icing performance of the resultant coatings is excellent. Ice formation process on aluminum film was delayed by more than 300 s at −19 °C. A purpose-built equipment was designed to investigate the placement orientation of coated samples on anti-icing performance. It has proved that a small angle of inclination had great benefits to the anti-icing performance of the superhydrophobic coating. Moreover, the nanocomposite coating has its superior deicing characteristic. Ice adhesion strength tested is lower than 10 kPa, denoting ice can be detached naturally by the action of the wind or its own weight. The anti-icing mechanism was proposed based on nucleation theory and heat transfer physics, which will give further guideline for developing superior anti-icing coatings. [Display omitted] • Robust superhydrophobic coating (>160°) was prepared with excellent icephobicity. • Icing time on the nanocomposite coating was delayed more than 300 s at −19 °C. • Fabricated coating with extremely low ice adhesion strength can be used repeatedly. • Superhydrophobicity maintains in many substrates with various preparation methods. [ABSTRACT FROM AUTHOR]

Icephobic coatings offer an effective solution for protecting infrastructures subjected to harsh cold-weather environments. Aqueous self-lubricating coatings, derived from the principles of ice skate sliding over ice, provide a cost-effective anti-icing method. Here, we fabricate aqueous self-lubricating coatings by adding polydimethylsiloxane-poly (ethylene glycol) (PEG-PDMS) copolymers to a PDMS matrix. We analyzed the wettability, morphology, and topography of the fabricated coatings using a goniometer, scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. Differential scanning calorimetry (DSC), push-off and centrifugal tests detailed the icephobic characteristics of the coating surfaces. Blending PEG-PDMS into the elastomeric matrix enhanced the effective contact area between the water droplet and the coating; the formation of hydrogen bonds between water molecules and the hydrophilic functional groups of the coating produced this effect, and water molecules spread readily over the surface. Increased concentrations of these functional groups increased the freezing-delay time and reduced ice adhesion strength, likely owing to the formation of a quasi-liquid-like layer. Nonetheless, the immiscibility of the PEG-PDMS copolymer within the PDMS matrix can negatively affect wettability and the icephobic characteristics of the coatings. An optimized copolymer content of 5% produced a durable icephobic aqueous self-lubricating coating. [Display omitted] • Increasing the PEG-PDMS copolymer content tends to enhance surface wettability. • Changing copolymer percentage results in positive effects on the icephobic characteristics. • The effect of the miscibility of the copolymer in the elastomer matrix on the freezing-delay time is investigated. • The push-off and centrifugal tests are used to evaluate the effect of PEG-PDMS content on ice adhesion strength. [ABSTRACT FROM AUTHOR]

• A new approach was proposed to enhance durability of icephobic coatings. • Fibres helped to mitigate the impinging energy and prevent stress concentration. • Ice adhesion strength was maintained below 10 kPa after rigorous erosion impacts. • Low ice adhesion was attributed to the reduced number and shallowed surface cavities. Icephobic performance of low-ice adhesion polymeric coatings has been studied intensively for passive ice protection. However, limited efforts were conducted to identify strategies for enhancing the durability of the coatings to maintain low ice adhesion after erosion impact. In this work, we developed and investigated several polyurethane-based nanocomposite and fibre-reinforced coatings to understand the deteriorating behaviour of the coatings under rigorous impinging erosion tests and the subsequent impact on ice adhesion. The inclusion of fillers resulted in up to 38 points increase in Shore hardness relative to the pristine PU coatings. The ice adhesion strengths on 3 wt% nanoparticle-reinforced coatings after the erosion tests were nearly halved, whereas, a 5-fold reduction was observed on 3 wt% fibre-reinforced coatings compared to that of the pure PU coatings. Our results indicated that the incorporation of fillers was effective in reducing the ice anchoring points, and that, after the impingement, the icephobic performance was retained by either lowering surface roughness or by minimizing surface deterioration. Fibres took a more effective role in limiting crack initiation and resisting crack propagation. The ice adhesion strength of the coatings increased from 5.6 kPa to 8.4 kPa with 20 wt% carbon fibres incorporated PU coatings, essentially keeping the adhesion below 10 kPa even after rigorous impinging tests and a ∼10-fold reduction in ice adhesion strength as compared to the pure PU coatings. The incorporation of the fibres led to enhanced durability and retention of excellent icephobic performance via a mechanism that is adaptable to other polymeric coatings. [ABSTRACT FROM AUTHOR]

HD lubricant is more effective than PDMS and PHMS to prepare a slippery liquid-infused porous surface (SLIPS) for anti-icing application. The formation of solid HD crystals under freezing condition makes the HD-infused surface physically smooth and chemically homogenous, decreasing the ice adhesion strength and the interface abrasion of HD. • SLIPS is easily fabricated by infusing lubricant into porous polymer matrix. • The solid nature of HD under freezing condition favors the robust icephobicity. • Affinity between matrix and lubricant is important to anti-icing robustness. • This work helps to select lubricant and matrix to design robust icephobic SLIPS. 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. [ABSTRACT FROM AUTHOR]