An intelligent icephobic coating based on encapsulated phase change materials (PCM)

Abstract

The phase change materials (PCMs) have attracted great interest for applications as smart icephobic coatings because of their capability to restore and release energy. PCMs release a large amount of energy as latent heat upon freezing, which is a stimuli-response behavior for anti-icing applications. Such materials embedded within coatings can be applied to exposed infrastructures to protect them against icing. Here, we encapsulated a mixture of PCMs in a urea–formaldehyde (UF) shell by in situ polymerization and then incorporated the microcapsules into a polydimethylsiloxane (PDMS) coating. Microcapsules 5–15 µm in diameter having a shell thickness of about 200 nm were fabricated. Investigating the chemical composition of the fabricated microcapsules confirmed that PCM material was successfully encapsulated within the UF shell. Moreover, the differential scanning calorimetry (DSC) analysis showed that the PCM preserved its phase-change characteristics when encapsulated and embedded within the matrix. Increasing the abundance of microcapsules within the coating lowered the ice nucleation temperature, verified by DSC, and increased the freezing-delay time because of PCM latent heat release. We utilized a custom-made apparatus, called micro-push-off set-up that allowed us to measure ice adhesion at the exact moment that the water droplet was completely frozen. Therefore, it was observed that the presence of the PCM microcapsules reduced ice adhesion strength, through either possible mechanism of the formation of quasi-liquid layer (QLL) or thermal expansion differences. Furthermore, lower ice adhesion resulted in reduced ice accumulation on the PCM-containing coatings, verified by the static accumulation test (SAT).