Nanofibrous Biomaterial-Based Passive Cooling Paint Structurally Linked by Alkane-Oleate Interactions

Area of Science:

• Materials Science
• Nanotechnology
• Sustainable Energy

Background:

• Passive radiative cooling materials offer electricity-free cooling, crucial for reducing greenhouse gas emissions and improving thermal comfort in underserved regions.
• Optimizing material properties, ease of application, and scalability are critical for real-world deployment of passive cooling technologies.

Purpose of the Study:

• To develop an easy-to-apply, paint-like passive cooling solution using embedded hydroxyapatite nanoscale fibers.
• To investigate the chemical structure, bonding behaviors, and cooling performance of the developed composite material.

Main Methods:

• Embedding hydroxyapatite nanoscale fibers in an oil-based medium to create a paint-like solution.
• Utilizing Fourier-transform infrared spectroscopy (FTIR) to analyze chemical structure and bonding.
• Evaluating outdoor cooling performance under solar irradiance.

Main Results:

• The composite material reflects 95% of solar energy and emits 92% of its radiative output through the atmospheric transparency window.
• Achieved an average subambient cooling performance of 3.7 °C under outdoor conditions (800 W m^-2 solar irradiance).
• Demonstrated tunable surface properties, enhanced durability, and potential for recycling.

Conclusions:

• The developed hydroxyapatite-based paint offers an effective and scalable passive cooling solution.
• Its properties make it suitable for outdoor applications, promoting sustainable cooling and circular economy principles.
• The material's ease of application and tunable characteristics position it as a promising candidate for passive cooling coatings.