Preparation And Optimization Of Network Microporous Polyimide Membrane For Gas Separation

Gas membrane separation technology,mainly using the mass transfer difference of different gases in the membrane to realize separation,has high economic value in capturing greenhouse gases such as CO₂.However,the technology also faces many challenges,such as Aging,Plasticization and Trade-off effect of organic membrane,which seriously restricts the service life and separation efficiency of the membrane.In order to suppress the above problems,this paper proposes to apply the network polyimide material to the gas membrane separation technology,and to optimize the comprehensive performance of the gas separation of the film and elucidate the structure-activity relationship between the network structure(crosslinking arm+crosslinking center)and the gas separation performance by changing the molecular chain structure skeleton and the molecular chain aggregation structure.The main research contents are as follows:Based on the molecular chain structure skeleton,a series of linear and network binaphthyl polyimide membranes with a variety of side groups,anhydrides,structures and topological arrangements,which can regulate the dihedral angle of Binaphthyl structure,were designed to study the regulation of molecular chain structure skeleton on the gas separation performance of Binaphthyl polyimide membrane.It was found that the construction of network structure with asymmetric double topological arrangement,could enhance its CO₂ permeability(+3310%).Based on the molecular chain aggregation structure,the performance of the network polyimide gas separation membrane with the properties of highly interconnected covalent bonds and fast curing gel,is comprehensively optimized from the physical and chemical level by changing molecular chain aggregation structure.For example,after Ti O₂ was added,the CO₂ permeability of the network film increased by 155%;After the crosslinking arm and center were expanded,the CO₂permeability of the network films increased by 183%and 560%respectively;After the side groups of crosslinking center and arm were pyrolyzed,the CO₂ permeability of network films increased by 29 times and 637 times respectively.