# Superhydrophobic Coating Solutions for Deicing Control in Aircraft
## 1 Introduction
Figure 2: Scanning electron micrograph of the hydrophobic coating showing soft micro-domains embedded on the wrinkled surface. Adapted with permission from Formation of Icephobic Surface with Micron-Scaled Hydrophobic Heterogeneity on Polyurethane Aerospace Coating, [PERSON], [PERSON], and [PERSON], ACS Applied Materials & Interfaces 2018 10 (43), 37517-37528, DOI: 10.1021/acsami.8b13403. Copyright 2018 American Chemical Society [16]. The effectiveness of a series of coatings composed of amphiphilic silicone polyurethane (AmSiPU) was tested for its anti-icing capabilities [17; 18]. While these types of coatings have been previously researched for their antifouling potential, their use for anti-icing purposes remains relatively unexplored. A range of amphiphilic polyurethane-based coatings were produced, containing both hydrophilic polyethylene glycol (PEG) and hydrophobic polydimethylsiloxane (PDMS) with variations in both molecular weight and composition. The surface of these coatings was analyzed, revealing the presence of both PDMS and PEG moieties and confirming their amphiphilic properties. The coatings were then tested for their ability to prevent ice adhesion, with particular attention given to the relationship between their anti-icing performance and water absorption and barrier properties. The role of innovation aimed to limit accidents caused by ice adhesion on aircraft surfaces poses a significant weight, highlighting the need for AIPS on board. Nevertheless, the downside of AIPS is its added complexity and increased fuel consumption. A potential solution to this is to use PIPS or seek ways to decrease the energy consumption of the AIPS. Superhydrophobic coatings are one such innovative development that could help reduce water adherence on surfaces and subsequently, fuel consumption. The cost associated with AIPS could potentially be decreased by utilizing superhydrophobic or icephobic coatings. Such coatings can effectively decrease ice adhesion and are thus commonly used. The question remains whether these coatings will prove to be a solution for the cost issue at hand. In these commentaries [19], the author makes a wide comparison among different ways to face ice adhesion-related problems and solutions. Superhydrophobic and icephobic coatings are currently being studied to determine their level of hydrophobicity. Various methods are being developed to adapt existing experimental data to be applied to aircraft. However, it is important to consider the durability of these coatings and, even though some of them have the potential to reduce AIPS power consumption, many do not possess adequate erosion resistance for practical use. To aid manufacturers, guidelines for aircraft erosion tests have been devised. Using superhydrophobic coatings, the extent to which AIPS power consumption can be reduced is dependent on the level of hydrophobicity utilized. Developing coatings that can resist erosion is the primary obstacle faced by manufacturers and designers and the demand for coatings that are superhydrophobic and icephobic arises from this need. Critical components like leading edges, slats, or vertical tails are strongly affected by ice formation decreasing flight reliability and safety. This work [5] mainly proposed two aims focused on coating design with icephobic properties and, on the other side, developing an innovative tool for wettability assessment. While in the first case, the study addresses coating multifunctional properties including livery effect and resistance to adhesion and abrasion, in the second one the authors attempt to reproduce the thermodynamic conditions like pressure and temperature present at flight altitudes. In these papers [20; 21], the authors evaluated the performance of SHS in preventing ice formation as a function of their durability in terms of erosion coupled with active deicers (Figure 3).