Fabrication of superhydrophobic bilayer composite coating for roof cooling and cleaning. (12th July 2021)

• Record Type: Journal Article
• Authors: Xi, Yulin; Yang, Zhangbin; Zhang, Jun
• Is Part Of: Construction & building materials. Volume 291(2021)
• Publication Date: 2021-07-12
• Subjects: Low-density polyethylene (LDPE) -- Lotus inspired -- Cooling property -- Titanium dioxide (TiO2) -- Chromium trioxide (Cr2O3); Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123283
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: The water contact angle of the SBS/SiO2 superhydrophobic coating is about 160°. The near infrared reflectance are enhanced in cooling composites. In temperature test, the finished temperature are reduced in cooling composites. Abstract: Building energy consumption is an important part of energy consumption. Cooling materials can be applied to reduce building energy consumption. In this study, chromium trioxide (Cr2 O3 ) and titanium dioxide (TiO2 ) were introduced into low-density polyethylene (LDPE) matrix to prepare the solar-infrared reflective layers, then styrene–butadiene-styrene triblock copolymer (SBS) and surface functionalized nano-silicon dioxide (SiO2 ) superhydrophobic coating was constructed on the surface forming bilayer composites applying for building roof. It was found that SBS/SiO2 coating had higher roughness, which provoked a soaring contact angle of about 160° realizing superhydrophobic surfaces. Withal, the contact angle was invariant nearly 160° after dropping the solution of calcium chloride (pH = 6), acid (pH = 2), and alkali (pH = 13) on the surface, which engendered chemical stability and anti-pollution property. Subsequently, the emissivity of LDPE and 10 wt% Cr2 O3 composites coated with SBS/SiO2 coating (LDPE/Cr-10/S) as well LDPE and 10 wt% TiO2 composites coated with SBS/SiO2 coating (LDPE/Ti-10/S) were increased to 83% and 83.9% along with high near-infrared reflectance was 47% and 63.1% separately. Simultaneously, when the initial temperature was 24 °C for 1 h under strong light irradiation in indoors, the final temperature of glass was 69 °C while the finished temperature of LDPE/Cr-10/S and LDPE/Ti-10/S were reduced to 30.5 °C and 25.8 °C respectively, showing the excellent cooling property.