A recent article in Advanced Functional Materials introduces a dual-mode film made with nano-engineered scattering fibers derived from upcycled chip bags.
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The film is designed to manage heat sustainably by absorbing solar energy in cold conditions and reflecting it in warm ones. By combining nanomaterials with recycled content, the study presents a scalable and environmentally responsible approach to improving building energy efficiency.
Background
Buildings account for a significant portion of global energy use, largely due to heating and cooling needs. Conventional thermal materials often lack the ability to respond to seasonal shifts and can lead to excessive energy use. The film developed in this study addresses that gap with a dual-function design: it absorbs solar energy during winter to help retain heat and reflects solar radiation during summer to promote cooling.
The film is constructed using a biopolymer base—polycaprolactone (PCL)—combined with silica nanoparticles, creating a lightweight, porous structure. The addition of highly scattering nanofibers enhances both solar absorption and thermal emission. Importantly, the use of recycled materials like chip bags supports the film's sustainability goals while minimizing production waste.
The Current Study
The fabrication of the dual-mode film began with the preparation of a 5 wt.% solution of PCL, which was dissolved in chloroform. This mixture was used to produce nanofibers through a method known as solution blow spinning (SBS). Silica nanoparticles were added in varying concentrations to evaluate their effects on the film’s thermal and mechanical properties.
The resulting mixture was sprayed using a commercial airbrush onto a rotating collector. The collector was wrapped in reflective aluminum foil or upcycled chip bags, which helped optimize the collection process. This setup allowed the nanofibers to form a continuous, nonwoven film that maximized surface area for solar absorption and thermal emission.
To assess thermal performance, the films were exposed to two controlled light intensities: 750 W/m² and 525 W/m², representing “summer” and “winter” conditions. Temperature changes were recorded and compared against conventional materials, including graphite-Al foil. The film’s effectiveness was evaluated based on its ability to absorb and emit heat, demonstrating its potential as an energy-efficient solution for passive thermal regulation.
Results and Discussion
The results showed that the dual-mode film offered improved thermal management compared to conventional materials. During simulated winter nighttime conditions, the film maintained a temperature of approximately -6.2 °C, while graphite-Al foil dropped to -8.3 °C. This higher temperature indicates the film’s reduced thermal emission. It limits radiative heat loss, which is especially beneficial in colder environments.
When exposed to solar irradiation under summer-like conditions, both the film’s ink side and the graphite-Al foil reached similar temperatures. This suggests that the film can effectively absorb solar energy in winter to support passive heating, while also allowing for gradual heat dissipation in warmer weather.
One of the most notable results was the film’s ability to maintain a temperature roughly 16.5 °C higher than the surrounding air in cold conditions. This highlights its strong solar absorption and heat retention capabilities. Such performance makes the film well-suited for use in building retrofits, providing a passive approach to indoor temperature regulation without relying on conventional heating systems.
The film's flexibility and adaptability also allow it to conform to irregular or complex surfaces, making it useful in various settings beyond residential buildings. Its structure could integrate into architectural designs where traditional rigid materials are less effective.
The scalability of the SBS fabrication process makes it an attractive choice for future energy-efficiency products. The proposed technology not only utilizes available waste materials but also reduces the reliance on non-renewable resources, aligning with global sustainability goals.
By demonstrating the dual capabilities of heating and cooling, the research articulates the potential impact on energy consumption and climate change mitigation globally.
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Final Note
This dual-mode film demonstrates how nanomaterial design, sustainable sourcing, and scalable manufacturing can work together to address thermal management challenges. Its versatility and performance point to promising directions for future building materials focused on energy efficiency and environmental impact.
Journal Reference
Song Q., et al. (2025). Dual-Mode Film Based on Highly Scattering Nanofibers and Upcycled Chips-Bags for Year-Round Thermal Management. Advanced Functional Materials. DOI: 10.1002/adfm.202425458, https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202425458