乙烯醋酸乙烯酯/二氧化硅超疏水辐射降温薄膜的制备及性能

Fabrication of Superhydrophobic Porous Poly(ethylene-vinyl acetate)/SiO_(2) Film for Daytime Radiative Cooling

辐射降温材料通过在太阳光波段(0.3~2.5μm)反射太阳光并通过大气透明窗口波段(8~13μm)将热量辐射到寒冷的外太空以实现表面的自发降温,这是一种可持续发展的制冷方式。然而,材料在户外长期使用过程中会受到雨水冲刷或灰尘沾污而使降温效果受到严重影响。文中通过溶剂交换法制备了具有多孔结构的乙烯醋酸乙烯酯/疏水二氧化硅(EVA/SiO_(2))复合超疏水辐射降温薄膜。复合薄膜表面的水接触角为160.4°,滚动角为2.6°;在太阳光波段的平均反射率可达96%,大气透明窗口波段的平均发射率为94%。在炎热强日光照射下的空气流通环境中,该薄膜可实现比周围环境平均温度低7℃;在无空气对流和传导的理想条件下可达到12℃的平均降温。薄膜的超疏水自清洁特性可使其表面避免被外界污染从而保持稳定的光学性能和降温效果。该材料适用于户外需要降温的领域,应用前景广阔。

Passive daytime radiative cooling technology offers a sustainable way to cool objects by reflecting sunlight and radiating heat through atmospheric transparency window simultaneously.However,the cooling performance of materials might be impacted by water droplet and dust accumulation in longtime outdoor application.Herein,a solvent exchange method was demonstrated for fabricating a superhydrophobic radiative cooling film that consists of microporous poly(ethylene-vinyl acetate)(EVA)matrix with hydrophobic SiO2 microspheres randomly distributed.The obtained EVA/SiO_(2)film exhibits a water contact angle of 160.4°and sliding angle of 2.6°.The hybrid film reflects 96%solar irradiance and has an average emissivity of 94%,which could achieve 7℃in open air below ambient temperature during daytime under direct sunlight and 12℃with isolating heat convection and conduction.In addition,the self-cleaning properties help prevent the film from contamination,and make the surface maintains stable cooling performance.The film is suitable for outdoor fields requiring cooling,which has a broad application prospect.