Scalable Monolithic Film with Adaptive, Gradual Haze Modulation and Switchable Reflectance

Efficient daylight harvesting and solar heat management present persistent challenges in building energy management. Existing solutions often rely on complex, multi-layered systems or offer limited adaptability. Here, we introduce a scalable, monolithic film that achieves bimodal-responsive synergistic opto-thermal regulation. This film, named S-PTFM, is a composite of poly(trifluoroethyl methacrylate-co-methyl methacrylate) microspheres (PTFM) embedded within a polydimethylsiloxane (PDMS) matrix. The S-PTFM film exhibits unique dual-responsive optical properties: it can dynamically modulate its integrated solar reflectance from 7.1% ± 0.3% (unstretched) to 40.7% ± 1.3% (stretched) via mechanical strain. Concurrently, it demonstrates intrinsic temperature-responsive visible light dimming, with haze values increasing from 37.7 to 61.2% as the temperature increases from 13.2 to 50.4 °C. This dual functionality enables adaptive adjustment of direct sunlight intensity, significantly enhancing indoor comfort and energy savings. Our straightforward and highly scalable preparation method yields large-area films (up to 150 × 21 cm) with a certain degree of mechanical durability (maintaining performance after 200 cycles). Simulations confirm the film's substantial potential for building energy reduction, projecting annual energy savings of up to 41.2 ± 1.8 GJ in tropical climates (e.g., Honolulu), while also providing comfort benefits in colder regions due to its adaptive nature. This adaptable, cost-effective, and durable film represents a promising solution for next-generation energy-efficient buildings.