Facile Access to Energy-Efficient Heterostructured Films via Scalable Planar Frontal Polymerization.

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Scalable and sustainable fabrication of heterogeneous polymer films is crucial for advanced materials.
• Existing methods often lack efficiency or scalability for complex structures.

Purpose of the Study:

• To present a planar frontal polymerization (FP) strategy for fabricating vertically graded heterogeneous films.
• To investigate the optical and cooling performance of these novel films.
• To demonstrate the scalability and industrial applicability of the FP method.

Main Methods:

• Utilized gravitational/buoyancy-oriented assembly of optical microspheres to create vertically graded photonic heterostructures.
• Employed planar frontal polymerization (FP) for self-sustaining and spatially precise immobilization of the heterostructure.
• Characterized the optical properties (solar reflectance, infrared emissivity, structural color) and cooling performance of the fabricated films.

Main Results:

• Achieved high solar reflectance (≈0.96) and enhanced infrared emissivity (≈0.98) with the heterogeneous films.
• Demonstrated tunable structural colors due to the photonic crystal properties.
• Observed significant passive cooling performance, achieving ≈7.0 °C sub-ambient daytime cooling, surpassing state-of-the-art designs.
• Validated the scalability and convenience of the planar FP strategy for industrial production.

Conclusions:

• The planar FP strategy provides a sustainable and scalable route for producing heterogeneous films with tailored optical properties.
• These films exhibit excellent solar reflectance, infrared emissivity, and passive cooling capabilities.
• The developed technology holds significant promise for applications in building envelopes and energy-efficient materials.