Characterization and Performance Enhancement of Multifunctional Aerogel Paint Composites

Abstract

There is urgent demand to develop energy-efficient building materials, where massive energy is often consumed in hot-climate regions for active building cooling via air-conditioning. This thesis is dedicated to the synthesis and characterization of aerogel-incorporated functional paints, in collaboration with our industrial partner. Their materials properties and performance are evaluated for passive radiative cooling, thermal insulation, enhanced light reflection and surface self-cleaning. To develop multifunction composite paints, this thesis also presents a lab-made silica aerogel (SA)infused composite paint by mixing acrylic varnish, Span 80, silica aerogel (5 wt.%), and ethanol, which is then coated onto soda lime glass with a doctor blade. Comparative studies on paint samples with and without silica aerogels show a huge difference in optical, wetting and thermal performance. The SA microparticles-infused composite paint exhibits the enhanced solar reflectance (ρVIS-NIR), up to 15% in the visible and near-infrared ranges (0.3-2.5 µm), while maintaining excellent radiative cooling properties with 92% emissivity (εLWIR) in the atmospheric transparency windows (8-14 µm). Experimental characterization has shown that the treated composite possessed better hydrophobicity, with water contact angles of near 100°, while the untreated samples had a complete wetting behavior. In addition, the thermal conductivity of the treated composite was reduced by approximately 86%, resulting in a conductivity of 0.0657 W/mK from the original value of 0.476 W/mK for bare glass. The SA infusion has also enabled a 50% reduction in thermal conductivity, compared to ordinary paint, and higher wall thermal resistance. The proposed aerogel-based composite paints is able to significantly reduce building energy consumption by enhancing passive radiative cooling and thermal insulation, and sub-ambient cooling can even be achieved under ideal thermal insulation conditions. In addition, the proposed paint needs less maintenance owing to the superior surface durability against dust and aerosol contamination, therefore promising great potential for large-scale applications in hot and arid regions.

Date of Award	9 Dec 2024
Original language	American English
Supervisor	TJ Zhang (Supervisor)