Preparation And Performance Study Of Self-healing Superhydrophobic PIM-1 Composite Membrane Based On Cyano Conversio

During the"two sessions"in 2020,China proposed the"double carbon"goal of"carbon peak"and"carbon neutral".This will bring CO₂ capture,storage and utilization（CCUS）technology to a new research climax.Among them,membrane separation technology has the advantages of low investment,energy saving,simple operation and no phase change,which is a more effective method for CO₂ capture.Inherently microporous polymer PIM-1 is a class of polymeric materials with high permeability and moderate selectivity developed in recent years,which is expected to be a new generation of commercial gas separation membranes due to its high free volume fraction,excellent physicochemical stability and unique CO₂ separation properties.However,the gas selectivity and permeability of PIM-1 membranes cannot meet the actual industrial production requirements:（1）the carboxylation modification of PIM-1 as an effective method to improve gas selectivity has the research difficulties of complex transformation process,low efficiency and poor membrane formation characteristics;（2）the infiltrated liquid water will occupy the gas transport pore channel of PIM-1 membranes,thus reducing the gas permeability performance.In this paper,we address the above issues by.（1）The preparation and characterization of the required materials in conjunction with the experimental purpose.Based on the previous studies,the molecular weight of PIM-1was regulated by changing the amount of THF in the purification process;the carboxylation conversion efficiency of PIM-1 was improved by grinding,stirring,pressurization and temperature increase;the preparation of PVDF/GO/POTS@PIM-1 composite membrane was completed by designing electrostatic spinning and chemical vapor deposition operation schemes;the physicochemical properties of the material were investigated by various chemical and physical characterization methods.The physical and chemical properties of the materials were tested by various chemical and physical characterization methods.The above material preparation and characterization processes provide a good theoretical basis for the following mechanism summary and performance analysis.（2）An innovative hydrothermal method for carboxylation modification（C-PIM）of PIM-1 was used to achieve a carboxylic acid conversion rate of more than 90%within 10h.The conversion efficiency was nearly five times higher than the highest efficiency available,and the film-forming properties were retained.The CO₂/CH₄ selectivity of the prepared C-PIM membrane was 35.8 and the H₂/N₂ selectivity was 48.28,both of which exceeded the Robertson upper limit in 2008.Using molecular structure analysis,XRD,GPC,N₂ adsorption/desorption,and CO₂ adsorption/desorption tests,we concluded from microscopic to macroscopic characterization based on the dissolution-diffusion model that C-PIM membranes can improve both CO₂ adsorption selectivity and diffusion selectivity.（3）For the first time,a superhydrophobic composite layer（PVDF/GO/POTS@PIM-1）was prepared on the surface of PIM-1 membrane using electrostatic spinning and chemical vapor deposition techniques.The prepared superhydrophobic layer exhibited good connectivity with the PIM-1 membrane,with a water contact angle of 152.75±0.5°.The surface maintains superhydrophobicity under chemical corrosion（p H=1-14）,water impact（P=15.9 k Pa）,and hot water treatment（70°C）,and also exhibits some superhydrophobic self-healing properties.The water absorption of this PIM-1 composite membrane was reduced from 69%to 12%within 30 min,while maintaining the original high gas permeability of the PIM-1 membrane.In this paper,we successfully prepared C-PIM membrane with high gas selectivity and PVDF/GO/POTS@PIM-1 composite membrane with superhydrophobic self-healing property,which will significantly improve the preparation efficiency of PIM-1 modified membrane and its ability to be applied in complex working conditions,and improve the separation and capture capability of CO₂ and other gases,and provide new solutions to achieve the national"double carbon This will provide a new solution to achieve the national goal of"double carbon".