Bioinspired "Skin" with Cooperative Thermo-Optical Effect for Daytime Radiative Cooling

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Developing energy-efficient cooling materials is crucial for sustainable thermal management.
• Existing cooling technologies often face limitations in operability and scalability.
• Bio-inspired designs offer novel approaches to material functionality.

Purpose of the Study:

• To create a flexible, superhydrophobic, and reusable cooling material.
• To leverage the thermo-optical properties observed in polar bear fur.
• To enhance daytime radiative cooling performance.

Main Methods:

• Laminating a poly(dimethylsiloxane) film with a highly scattering polyethylene aerogel.
• Characterizing the material's porosity, pore size, solar reflectance, and thermal transparency.
• Evaluating the cooling performance under real-world metropolitan conditions.

Main Results:

• The cooling skin exhibits high porosity (97.9%) and a tailored pore size (3.8 ± 1.4 μm).
• Achieved superior solar reflectance (R̅sun ∼ 0.96) and high infrared transparency (τ̅PE,MIR ∼ 0.8).
• Demonstrated midday sub-ambient temperature drops of 5-6 °C, with a potential of 14 °C.

Conclusions:

• The developed cooling skin offers a promising solution for energy-saving thermal management.
• The generalized bilayer approach is versatile and applicable to various emitters.
• This technology bridges the gap between night-time and daytime radiative cooling, enabling cost-effective and scalable solutions.