微纳压印结构色纤维素膜的制备及其辐射制冷性能

Preparation and radiation cooling performance of cellulose film with micro-nano imprinting structural color

研究微纳压印结构色纤维素膜的制备及其辐射制冷性能。通过使用碱尿素体系溶解纤维素,制备出物理化学双交联的纤维素薄膜,利用薄膜吸水溶胀的特性,在纤维素薄膜上微纳压印正交光栅的微纳结构,使原本颜色单调的白色被动式日间辐射冷却材料成为结构性色彩新材料,并增强其辐射制冷效果。结果表明:薄膜压印后在可见光波段有更好的反射率,平均吸收率仅有19%,在大气窗口波段的发射率高达93%。在360 W功率的氙灯照射下,薄膜的表面温度比棉织物的表面温度约低3.4℃,与照射区间的环境温度对比降低了6℃;在平均661.6 W/m^(2)的太阳辐射照度下,微纳压印结构色纤维素膜背面温度比环境温度平均下降7.1℃;在500 W/m^(2)的太阳辐射照度下,最大辐射冷却功率为63.3 W/m^(2)。微纳压印结构色纤维素薄膜是一种绿色辐射制冷材料,可广泛用作辐射制冷物或建筑覆盖材料。

Preparation and radiation cooling performance of cellulose film with micro nano imprinting structural colors were studied.Alkaline urea system was used to dissolve cellulose,a physically and chemically cross-linked cellulose film was prepared.By utilizing the water absorption and swelling property of the film,the micro-nano structure of orthogonal gratings was micro-nano imprinted on the cellulose film,making the originally monotonous white passive daytime radiation cooling material into a structural color new material and enhancing its radiation cooling effect.The results showed that the film after imprinting had a better reflectivity in the visible light band,with an average absorption rate of only 19%,and emissivity was reached up to 93%in the atmospheric window band.Under the irradiation of a 360 W xenon lamp,the surface temperature of the film was below 3.4℃higher than that of the cotton fabric,which was reduced by an average of 6℃compared to the ambient temperature in the irradiation range.Under an average solar irradiance of 661.6 W/m^(2),the temperature on the back of the cellulose film with micro nano imprinted structure was decreased by an average of 7.1℃compared to the ambient temperature.Under solar radiation illumination of 500 W/m^(2),the maximum radiative cooling power was 63.3 W/m^(2).The cellulose films with micro-nano imprinting structural color was a green radiation cooling material.It could be widely used as radiation cooling material or architectural cover material.