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<p>Passive radiative cooling (PRC) materials enabling personal thermal management other than space cooling have taken attention of many scientists because of its social, environmental, and economic advantages. Among PRC materials, porous nanocomposite structures produced by non-solvent induced phase separation (NIPS) method including reflective particles have gained popularity with the hierarchical micro-nano pores enhancing solar reflectivity and thermal emissivity. Herein, PRC polyvinylidene fluoride (PVDF) (10 wt.%) porous nanocomposite films including zinc oxide (ZnO) nanoparticles were produced by NIPS, adjusting the percentage of water (3-7%) within the solvent-nonsolvent-water system. Optimization was carried out in drying temperature (120°C, 60°C, 20°C) of the porous nanocomposite films to get more heterogeneous and transparent structure with the minimum energy. Results showed that, optimum micro-nano hierarchical porous structure was obtained with 7% water according to SEM analyses, but the optimum film color could not be obtained for both 120°C, 60°C drying temperatures besides a possible deterioration. Lowering the drying temperature to 20°C, keeping the hierarchical porous structure, the minimum color deterioration was also obtained with a slightly higher cooling effect evaluated by a hotplate system including a sun simulator lamp. Summing up, a cooling effect of 3.85°C was obtained with the porous nanocomposite film dried at 20°C by a cost-efficient and eco-friendly manufacturing path.</p> |
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