On July 9, Science magazine online published the research progress entitled Hierarchical-morphology metafabric for scalable passive daytime radiative cooling jointly by Ma Yaoguang's team from COSE of ZJU and Tao Guangming's team from Wuhan National Laboratory for optoelectronic. This research has groundbreaking developed an optical metafabric with hierarchical morphology structure and mass preparation, which has excellent daytime radiation cooling capacity and is of great significance to realize efficient outdoor personal heat management.
However, because the current research is difficult to achieve wide spectrum regulation covering ultraviolet, visible and infrared, it is still a challenge to realize the effective cooling of human body in the hot outdoor environment with direct sunlight.
Ma Yaoguang's team together with his cooperators has made important progress in the research field of radiation cooling fabrics. They proposed an optical random metafabric with morphological hierarchical structure, which is graded according to the spatial structure of the fabric, the fiber structure and the micro nano structure inside the fiber. Different levels respond to different bands respectively, which optimizes the efficiency of spectral response, and effectively avoids the crosstalk of spectra in different bands, so as to realize the Efficient spectral regulation in whole 0.3-25μm band range. The research team combined optical metamaterial technology with batch fiber preparation technology, selected green, environmentally friendly and biodegradable polylactic acid as fiber raw material, introduced new optical characteristics of specific wave band, and obtained uniform and continuous metamaterial fibers. On this basis, the metafabric prepared by using mature spinning, weaving and lamination technology is in the solar radiation band (0.3-2.5 μ m) It has 92.4% reflectivity in the mid infrared atmospheric window band (8-13 μ m) It has a reflectivity of 94.5%. Metafabric can realize day and night radiation refrigeration lower than the ambient temperature all day; In the midday simulated human skin test (Guangzhou, November 28, 2020), the simulated skin temperature under metafabric can be 5-7 ° C lower than that of commercial fabrics of the same color (cotton, spandex, chiffon and hemp). In the cooling test of automobile model (Guangzhou, December 7, 2020), the internal temperature of the model covered with metafabric can be reduced by ~ 27 ° C compared with the commercial car cover and ~ 30 ° C compared with the model without fabric cover. In addition, metafabric also has a significant cooling effect on the actual human body exposed to sunlight (Guangzhou, December 7, 2020). Compared with white cotton fabric, it can cool the human body surface by more than 4 ° C.
Keep facing the world's scientific and technological frontier, the main economic battlefield, the major national needs and people's life and health, and constantly march in the breadth and depth of science and technology. the fabric has excellent wearability and is compatible with the whole textile industry, and is suitable for large-scale preparation and industrial application. At the same time, the main materials of metamaterial fabrics are environmentally friendly and biodegradable, which will not burden the environment.
In terms of cost, the research team introduced new materials into the fiber, and the fiber cost increased by only about 10%. Compared with ordinary clothes, the cost of a super material fabric garment increased by only about 1%. Under this small cost difference, it can bring excellent cooling performance. In terms of body feeling, the super material fabric has soft touch, skin friendly, comfortable and breathable. The fiber or fabric shape can be integrated into the related products of daily life through embroidery, cutting and sewing, with strong universality; It can adapt to any object surface, such as sunscreen clothes, tents, car covers, umbrellas or protect any person and object exposed to the sky and injured by the sun.
