Study On Passive Radiation Cooling Film Prepared By Non-Solvent Induced Phase Separation

Cooling technology can greatly improve the quality of human life.The widespread popularization of this technology not only provides a comfortable living temperature for human beings,extends the storage period of food and suppresses the extreme thermal environmental impact.Steam compression is the main strategy in refrigeration technology,which consumes a lot of electricity generated from fossil fuels and increases global warming.In order to reduce energy costs,alleviate greenhouse gas emissions,and reduce ozone depletion and related heat problems,"passive radiative cooling"（PRC）has attracted more and more attention as a zero-energy consumption and eco-friendly cooling strategy.In this paper through the solvent induced phase separation method,the introduction of small molecule surfactants and nanoparticles to large area with sunlight band high reflectivity,atmospheric window high emissivity of porous cooling film,achieve excellent"passive radiation cooling"performance,the film can be used as building cooling coating in the future.The research content of this paper is mainly developed by the following two aspects:Polymethacrylate（PMMA）with good chemical stability,acetone as good solvent,water as non-solvent,and the fourth phase amphiphilic molecule polyethylene glycol（PEG）was introduced,and the porous structure film was prepared by non-solvent induced phase separation（NIPS）.The temperature,humidity and PMMA concentration affected the structure of the prepared film.At the same time,the introduction of PEG molecules in the process of phase separation,can be used as a site of droplet nucleation growth,promote the water droplets in solution,can effectively control the morphology of the porous structure and increase porosity,increase the probability of infrared absorption/emission probability,is conducive to the radiation heat exchange between porous film and atmosphere,can realize the passive radiation cooling performance.To further optimize the passive radiative cooling effect,Si O₂ microspheres with high refractive index and excellent infrared characteristics were introduced on the basis of the original non-solvent-induced phase-separated porous films.The optimal conditions and optimal optical performance of the film were explored by controlling experimental variables such as Si O₂ particle size and environmental humidity.The film with high reflection of sunlight and high emission of atmospheric window is prepared.The film can achieve the cooling effect of7℃in outdoor noon,and can be used as energy-saving coating in the field of building cooling.