Mathematical Analysis Of Ionic Liquids Polymer Membranes And Molecular Dynamics Simulation Of Separated Gases

As a new type of green material,ionic liquids?ILs?polymer film combines the advantages of ILs and polymers,and has a good advantage in the field of gases separation.It has become a hot topic in the field of theory and application.However,the current research on ILs membranes mainly relies on experimental testing and searching.It is not clear in microscopic mechanism,and it is impossible to orient quantitative design regulation,which makes it difficult to realize industrial applications.Therefore,this thesis studies the ILs-polymer membranes from the theoretical aspect,mainly uses mathematical modeling and molecular dynamics methods to study the gases separation mechanism at the molecular level,and provides a scientific basis for the preparation and application of ILs-polymer membranes.In this paper,two monomeric PEO and PA6 are firstly connected,and a mathematical model of Pebax1657-block copolymer is established.The initial model is optimized by the steepest descent method with the goal of energy minimization,and the charge distribution algorithm is used to charge the atom of the polymer.To establish a more accurate polymer model.On the basis of molecular dynamics simulation,the microstructures of pure polymer membrane and ILs-polymer membranes were revealed at the microscopic level,and the mechanism of the two membranes in the process of separating and absorbing CO₂,CH₄ and N₂ gases.Using the radial distribution function,spatial distribution function,energy probability distribution and self-diffusion coefficient,the two membrane systems were calculated respectively,and the following conclusions were obtained:?1?In the pure Pebax1657 system,the polymer PEO segment is stronger than the PA6 segment.And the effect on CO₂ is the best.?2?In the[Bmim][BF₄]-Pebax1657 system,the anion and Pebax1657 are stronger than the cations,and mainly act on the flexible segment PEO.?3?In the ILs-Pebax 1657-gases mixed system,the anions and gases and Pebax 1657are both stronger than the cations.?4?The diffusibility of the ILs mixed membrane to the gases indicates that the addition of ILs can increase the diffusion rate of the gases in the membrane and increase as the ILs content increases.The above conclusions show that in the pure Pebax1657 film,mainly the flexible segment PEO plays a major role in the separation gas.In the ILs-polymer mixed membranes,the anion plays a leading role.The overall results show that in the pure Pebax 1657 membrane,mainly the flexible segment PEO plays a major role in the separation gases.In the ILs-polymer mixed membrane,the anion plays a leading role.The research results in this paper establish an important index-anion for the screening of ILs with higher gases solubility,which lays a theoretical foundation for the ILs membranes in mass transfer theory.