Researchers from Zhengzhou University and the University of South Australia (UniSA) have developed a bioplastic metafilm capable of passively cooling surfaces without electricity, according to a study published in
Cell Reports Physical Science. The film reflects nearly 99% of solar radiation and reduces surface temperatures by up to 9.2°C during peak sunlight.
Made from plant-based polylactic acid (PLA), the biodegradable metafilm uses a low-temperature separation technique to achieve 98.7% solar reflectance while minimizing heat gain. Field tests in China and Australia demonstrated average cooling of 4.9°C during the day and 5.1°C at night, with up to 6.5°C cooling maintained after prolonged exposure to acidic and ultraviolet conditions.
Unlike conventional passive radiative cooling systems based on petrochemical polymers or ceramics, this PLA-based film offers a biodegradable alternative with high solar reflectance, thermal emission, and durability.
Energy simulations suggest the metafilm could reduce annual building energy consumption by up to 13.1% in some cities, decreasing reliance on air conditioning. The researchers estimate potential savings of up to 20% in extremely hot regions.
“Our metafilm offers an environmentally friendly alternative to air-conditioning, which contributes significantly to carbon emissions,” said Yangzhe Hou, UniSA PhD candidate and co-author.
The team is exploring further applications in areas such as transport, agriculture, electronics, and biomedical cooling.
