Preparation Of Polymer Porous Membranes Using The Water Droplet Template Method And Evaluation Of Interfacial Evaporation Performance

The development of effective water treatment technologies is essential due to the world’s dramatic expansion and elevated degree of industrialization,which have caused problems with water pollution and a shortage of fresh water supplies worse.Solar steam generation（SSG）technology has great deal of potential to be utilized for the production of pure water,seawater desalination,and wastewater treatment.In SSG technology,the interfacial evaporation performance of photothermal materials is significantly determined by the structure of photothermal conversion materials,where the effective construction of water transport and vapor escape channels is a critical component.With its straightforward operation and effective pore formation,the breath figure approach is an innovative method for generating pore channels.The prepared pore channels have the characteristics of regular arrangement,ordered long range,and controllable size.Based on this,this paper adopts the breath figure method to prepare porous polymeric membrane materials with regular and ordered water transport channels and adjustable pore size for solar interfacial evaporation,providing new materials and new research ideas for this field.The research of this paper mainly includes:（1）A membrane with a highly regular arrangement of honeycomb macropore structure was prepared using poly（methyl methacrylate）as the substrate material and the breath figure method as the pore-making technique,and a PMMA-based composite membrane with polypyrrole coating attached（PMMA/PPy）was synthesized by surface chemical modification,and an interfacial evaporator（PMMA/PPy-EPE）with a two-layer structure was assembled and prepared using it as the photothermal evaporation layer and a polyethylene foam wrapped with plant fiber nonwoven as the heat insulation and thermal insulation base layer.It was discovered that evaporation rate and photothermal conversion efficiency of PMMA/PPy-EPE are 1.65 kg m^-2 h^-1 and 95.3%,respectively,under 1 k W m^-2 solar irradiation,and had excellent cycle stability and salt resistance performance.The removal effect of metal ions such as Na⁺and Mg²⁺in simulated seawater is remarkable,which is far below the drinking water standard prescribed by the World Health Organization and has outstanding desalination performance.（2）A PC with high toughness and high impact strength was selected as the base material with the objective of enhancing the mechanical properties of photothermal evaporation materials.The breath figure method was then employed as the pore-forming technology to produce a numerous,low-curvature through-porous PC.By modifying the surface chemically,a PC-based composite membrane with PPy coating（PC@PPy）was generated that exhibits a 9.26%elongation at break and strong toughness.The range’s 93%light absorption rating demonstrates excellent light absorption capability.An interface evaporator with a double-layer structure（PC@PPy-EPE）was constructed using PC@PPy film as the light-to-heat conversion layer and polyethylene foam wrapped in plant fiber non-woven fabric as the heat insulation bottom layer.Under 1k W m^-2 sunlight irradiation,the evaporation rate and photothermal conversion efficiency of PC@PPy-EPE were 1.783 kg m^-2 h^-1 and 93.57%,respectively,and showed good evaporation stability in 10 evaporation cycle experiments.It still maintained high evaporation rate(1.582 kg m^-2 h^-1)and light-to-heat conversion efficiency（79.79%）in 20wt%Na Cl solution,and had high evaporation stability and excellent salt resistance.In addition,the PC@PPy-EPE evaporator has an interception rate of more than 99%for metal ions in simulated seawater,has excellent seawater desalination performance,and has a remarkable purification effect on sewage containing organic dyes.