Printable polymer nanocomposites for scalable and architected radiative cooling

Area of Science:

• Materials Science
• Optics
• Thermal Engineering

Background:

• Space cooling and lighting account for 25% of global electricity consumption.
• Existing daytime radiative cooling technologies often involve porous planar coatings that block visible light and lack durability.

Purpose of the Study:

• To introduce a design principle linking polymer viscoelasticity to particle dispersion and optical scattering for radiative cooling.
• To develop printable composite materials for efficient and durable daytime radiative cooling.

Main Methods:

• Utilizing rheology-optics coupling to design printable polydimethylsiloxane-zirconium oxide composites.
• Characterizing solar reflectance and mid-infrared emissivity of the developed coatings.
• Evaluating cooling performance and durability under various stress conditions.

Main Results:

• Achieved high solar reflectance (~97.3%) and mid-infrared emissivity (~96.9%) with low filler loading (~4.5 vol.%).
• Demonstrated sub-ambient cooling up to 7.4 °C, reducing electricity use by 37% compared to commercial paint.
• Developed rheology-tunable ink enabling direct ink writing of daylight-regulating cooling architectures.

Conclusions:

• The developed polydimethylsiloxane-zirconium oxide composites offer a practical and versatile platform for radiative cooling.
• This technology can significantly reduce energy demand for cooling and lighting in buildings.
• The rheology-optics coupling principle provides a scalable approach for designing advanced radiative cooling materials.