A breathable and environmentally friendly superhydrophobic coating for anti-condensation applications

Abstract

Condensation poses a serious challenge to the mechanical durability and sustainable development of modern buildings in tropical environment. Moisture condensation and absorption in architecture causes inconvenience and requires extra maintenance measures. A mechanically durable anti-condensation coating that displays very low affinity with moisture is promising for applications on wall and ceiling of buildings. A main challenge in the fabrication of anti-condensation surface lies with the requirements of preventing water accumulation on the surface while maintaining the breathability of substrate. In this study, a breathable anti-condensation coating has been developed on cementitious substrates based on bio-based epoxy resins. The coating presented water repellency and a condensation delay time of 50 min when compared to the uncoated counterpart at a sub-cooled temperature of 8 °C. The excellent tolerance against condensation was verified after 200 h continuous condensation test according to ISO 6270 standard. The coating also displayed good breathability and moisture resistance, which are key to the inhibition of bacteria growth and structural deterioration in architecture. Moreover, the superhydrophobic sample demonstrated a 9.7% increase in thermal conductivity over the uncoated substrate. Mechanical tests showed good adhesion between the coating and the substrate. The coated area of cementitious substrate maintained its superhydrophobicity even after the bulk coating was removed. The coating also displayed superior mechanical durability over the state-of-the-art anti-condensation coatings. The reported method provides a practically useful and environmentally friendly solution to mitigate water absorption problem of concrete based architectures.