Superhydrophobic and icephobic polyurethane coatings: Fundamentals, progress, challenges and opportunities

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.