Shape-Stabilized PEGylated Silica Aerogel-Composite as an Energy Saving Building Material.

Balancing thermal and visual comfort in buildings necessitates effective insulation to counteract heat loss and gain, especially with temperature variances. One promising approach is to combine phase change materials, such as poly(ethylene glycol) (PEG), with high-performance insulators like silica aerogel (Si ag ). To bolster opto-thermal performance in building envelopes, we introduce a smart insulation composite material through PEG integration, i.e., PEGalyation with Si ag . Central to this thermal behavior is the PEG's phase change properties, which foster a shape-stabilized framework with Si ag through their porous confinement. Preliminary observations indicate notable capabilities of obstructing near-infrared light while preserving satisfactory visible transparency. An optimized Si ag @PEG composite with 5% loading of PEG has the visible range transmission of ∼92%, a decrease of ∼72% in thermal conductivity which is lower than pure glass and PEG, leading to a temperature dependent switchable hydrophobic to hydrophilic wettability characteristics. As a prototype window, the thermal performance evaluation of the synthesized composite, through experimental and computational studies, shows a decrease in indoor temperature of ∼20% with a higher temperature difference of ∼20 °C between outdoor and indoor weather conditions. This lightweight composite can act as sponge media to fill inside the double-paned window and for retrofitting existing glazing to boost the energy efficiency of buildings with facile manufacturing and scalability.