Development of anti-icing coatings for sports application

• Main Author: Wu, Xinghua
• Other Authors: Chen Zhong
• Format: Theses and Dissertations
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Materials::Nanostructured materials; DRNTU::Engineering::Materials::Composite materials; DRNTU::Engineering::Materials::Functional materials; DRNTU::Engineering::Materials::Material testing and characterization
• Online Access: https://hdl.handle.net/10356/81282; http://hdl.handle.net/10220/47508
• Institution: Nanyang Technological University

Undesired ice accumulation on outdoor sports facilities leads to severe economic issues and even loss of lives. Great efforts have been made to fabricate ice prevention surfaces or facilities since 1800s. The utilized methods can be categorized into four types: mechanical methods, chemical methods, thermal methods and combined methods (combing two or three former referred methods). Considering the economic impact and additional labour burdens, chemical methods are commonly adopted and widely studied. To avoid numerous environmental effect of drain-off chemicals, icephobic coatings, as effective passive anti-icing methods, have attracted much attention in recent decades. However, less attention has been paid on development of the anti-icing coatings for sports facilities and other related applications that requires additional properties including mechanical durability, transparency, easy processability and so on. With expectation to repel incoming water before ice formation, superhydrophobic coatings that exhibit superior water repellency and bouncy effect, have been widely studied since 1997. However, not all superhydrophobic coatings present anti-icing behaviours due to water condensation. This study begins with the investigation of the effect of water condensation on superhydrophobic coatings with different microstructures. To design superhydrophobic coatings with different microstructures, a sol-gel method was employed with adjustment of the weight ratio of nanoparticles with different surface energies. One of the prepared coatings demonstrated robust icephobicity with low ice-adhesion strength of ~ 60 kPa under water condensation conditions; at the same time, it also displayed a low ice-nucleation temperature of ~-26 degree celsius and low icing probability. With a strong demand for aesthetics appearance, transparent anti-icing coatings are needed for various applications. However, the well-studied superhydrophobic coatings are usually translucent or opaque because of the micro-nanostructures which greatly affect light transmittance. The state-of-the-art slippery liquid infused porous surface (SLIPS), which presented extremely low ice adhesion, can achieve a high transparency by choosing the substrate and lubricant liquid with matching refractive indices. However, the mechanical property of both kinds of coatings is weak due to the presence of porous microstructures. To obtain high transmittance and good mechanical properties, a new strategy is designed to fabricate a mechanical durable transparent anti-icing coating by a low cost sol-gel method. The prepared coatings presented a transmittance as high as 99 %, low ice adhesion, good condensation resistance, anti-frost and durable mechanical properties. Besides, this coating demonstrated self-cleaning properties and repellency to various liquids with surface energy ranging from 72.8~22.1 mJ/m2. With the demonstrated excellent properties, this coating is promising for anti-icing applications for sports applications and other applications that require good transparency and mechanical durability. Room-temperature processed anti-icing coatings are highly desirable for large outdoor structures besides the low-cost consideration. In this work, a room-temperature processable, fluorine-free anti-icing coating was designed and investigated. With the design of dual-size nanoparticle fillers, coatings presented denser micro-nanostructure than the ones with singe-size fillers. This denser structure of the dual-size coatings enabled better water repellency and anti-icing performance in terms of low ice adhesion and less ice accumulation than the single-size coatings and a commercially obtained polyurethane (PU) coating. To ensure the robustness and durability of the developed coatings, comprehensive mechanical and durability studies including tape adhesion, pencil hardness, dolly-pull tests, nano-indentation, ultraviolet (UV) irradiation, water condensation and sand erosion were carried out according to available ISO or ASTM standard methods. The dual-size coating presented better mechanical properties and UV resistance than the single-size and the PU coatings. Comparable sand erosion resistance were obtained on the dual-size particle coatings. To sum up, robust and durable anti-icing coatings which can satisfy different application requirements have been designed and developed successfully. The preparation method of these coatings follows some general principles of being simple, scalable, and low cost. Specially, the design of robust transparent coatings is a relatively new territory for passive anti-icing applications. Comprehensive mechanical and durability tests in these studies are novel, and can serve as a foundation for future evaluation of the practically applicable anti-icing coatings. The use of different surface energy nanoparticles, duals-size nanoparticles and mechanical-force induced deagglomeration are very enlightening methods for future design of functional coatings.