Fabrication Of Light Controlled Ordered Polymer Porous Films By Non-Solvent Induced Phase Separation

As a new type of functional structure,porous microstructure plays an increasingly important role in the fields of electronics,optics,energy and separation.Common methods for preparing such microstructures include template method,breath figure method,and photolithography,but these traditional manufacturing methods usually require molecules with special structures or rely on expensive equipment,which limits the application of such structures.In order to solve these problems,this paper puts forward a new kind of non-solvent induced phase separation method to controllable and large-area preparation of ordered porous structures.And based on this structure,a series of porous film structures with selective absorption,reflection or transmission of light at special wavelengths were prepared by introducing functional molecules or functional structures,which can effectively control the propagation direction of incident light.The research work of this paper is carried out from the following two aspects:Firstly,polymethylmethacrylate（PMMA）with good film-forming property and an Azo polymer with green light absorption polydisperse Red 1 methacrylate（pDR1M）were selected.Chloroform was selected as a good solvent and methanol as a non-solvent,the ordered and large-area porous polymer membrane was prepared by non-solvent induced phase separation method.By adjusting the ratio of PMMA:pDR1M,the time of soaking in the chloroform/methanol solution,the evaporation temperature,the type of mixed solvent,the factors affecting the formation of the polymer porous membrane structure were explored,and the phase separation process was monitored and theoretically analyzed.It was found that when the PMMA:pDR1M ratio was 75/1 and immersed in chloroform/methanol solvent for 5 s,an ordered porous film could be formed at room temperature.The prepared porous structure can be used as a template for preparing a microlens array and has strong light scattering performance.Meanwhile,the effective shielding of the porous film against green light is realized by the absorption of azo polymer.Secondly,the ordered porous structure with pore size of 5μm was prepared by non-solvent-induced phase separation method,and 250 nm SiO₂ modified by silane coupling agent KH-570 was sprayed onto the surface of the porous structure combined with spraying method,after HF etching,micro/nano composite multistage porous films were prepared.By adjusting the concentration of polymer PMMA to 10%and the etching time to 60 min,the optimal conditions for forming micro/nano thin films were explored.The formed special aperture size can effectively reflect the incident short-wave infrared light and transmit the radiated long-wave infrared light,thus exhibiting efficient passive radiation cooling performance,and can achieve a temperature drop of about 8℃ at noon in summer The effect can be applied to energy-saving coatings of buildings.