阅读说明：本技术 一种研究复合膜界面聚合反应机理的耗散粒子动力学方法 (Dissipative particle dynamics method for researching interfacial polymerization reaction mechanism of composite film ) 是由 麦兆环 桂双林 袁书珊 熊继海 吴九九 夏嵩 张苗辉 于 2019-09-11 设计创作，主要内容包括：本发明属于高性能膜材料领域,具体涉及一种利用计算机模拟技术研究复合膜界面聚合反应机理的耗散粒子动力学方法。所述方法包括如下步骤：(1)确定界面聚合体系的水相和油相中溶剂与单体的组成；(2)分别构建水相中溶剂与水溶性单体的DPD模型和油相中有机溶剂与油溶性单体的DPD模型；(3)建立由水相和油相构成的界面聚合反应体系DPD模型；(4)计算各DPD珠子之间的相互作用参数,即保守力参数；(5)利用Materials Studio软件进行DPD模拟,系统平衡后,得到各DPD珠子的运动轨迹文件及相关计算文件；(6)根据模拟结果观察界面聚合反应所生成复合膜分离层的结构特性,结合计算文件研究界面聚合过程中决定分离层性能的影响因素。本发明为系统的研究复合膜分离层界面聚合反应的主控因素提供了理论依据,同时对改进界面聚合反应的实验工艺制备高性能分离膜具有重要的指导意义。(The invention belongs to the field of high-performance membrane materials, and particularly relates to a dissipative particle dynamics method for researching a composite membrane interfacial polymerization reaction mechanism by utilizing a computer simulation technology. The method comprises the following steps: (1) determining the composition of a solvent and a monomer in a water phase and an oil phase of an interfacial polymerization system; (2) respectively constructing a DPD model of a solvent and a water-soluble monomer in a water phase and a DPD model of an organic solvent and an oil-soluble monomer in an oil phase; (3) establishing an interface polymerization reaction system DPD model consisting of a water phase and an oil phase; (4) calculating interaction parameters among all DPD beads, namely conservative force parameters; (5) carrying out DPD simulation by using Materials Studio software, and obtaining a motion trail file and a related calculation file of each DPD bead after system balance; (6) and observing the structural characteristics of the separation layer of the composite membrane generated by the interfacial polymerization reaction according to the simulation result, and researching influence factors determining the performance of the separation layer in the interfacial polymerization process by combining with a calculation file. The invention provides a theoretical basis for systematically researching the main control factors of the interfacial polymerization reaction of the separation layer of the composite membrane, and has important guiding significance for preparing the high-performance separation membrane by the experimental process for improving the interfacial polymerization reaction.)

1. A dissipative particle dynamics method for researching a composite membrane interfacial polymerization reaction mechanism is characterized by comprising the following steps:

determining various substance components and chemical structures thereof in a water phase and an oil phase of an interfacial polymerization system, wherein the water phase comprises water and water-soluble monomers, and the oil phase comprises an organic solvent and oil-soluble monomers;

step two, respectively constructing a DPD model of the water phase solvent and the water-soluble monomer molecules and a DPD model of the organic solvent and the oil-soluble monomer molecules in the oil phase;

step three, establishing a DPD structural model of an interfacial polymerization reaction system consisting of a water phase and an oil phase;

step four, calculating interaction force parameters among all DPD beads;

fifthly, carrying out DPD simulation by using Materials Studio software, and after the system is balanced, obtaining a motion trail file and a related calculation file of each DPD bead;

and step six, observing the structural characteristics of the separation layer of the composite membrane generated by the interfacial polymerization reaction according to the simulation result, and researching influence factors determining the performance of the separation layer in the interfacial polymerization process by combining with a calculation file.

2. The dissipative particle dynamics method for studying interfacial polymerization mechanism of composite membrane according to claim 1, wherein: the water-soluble monomer is one or more of piperazine, 2-methyl piperazine, 2, 5-dimethyl piperazine, 4-amino methyl piperazine, 2, 5-diethyl piperazine, alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin, delta-cyclodextrin, p-phenylenediamine, m-phenylenediamine, sym-benzenetriamine, diaminotoluene, ethylene diamine, propylene diamine, phenyl dimethyl diamine, 1, 3-diaminocyclohexane or 1, 4-diaminocyclohexane, and the concentration of the water-soluble monomer is 0.01-8.0 wt%.

3. The dissipative particle dynamics method for studying interfacial polymerization mechanism of composite membrane according to claim 2, wherein: the water-soluble monomer is preferably piperazine, m-phenylenediamine or cyclodextrin.

4. The dissipative particle dynamics method for studying interfacial polymerization mechanism of composite membrane according to claim 1, wherein: the organic solvent in the oil phase is one or more of n-hexane, cyclohexane, heptane, octane, naphtha, Isopar-E, Isopar-G, Isopar-L or mineral oil.

5. The dissipative particle dynamics method for studying interfacial polymerization mechanism of composite membrane according to claim 1, wherein: the oil-soluble monomer in the oil phase is a polybasic acyl chloride monomer and comprises one or more of trimesoyl chloride, paraphthaloyl chloride, isophthaloyl chloride, paraphthaloyl chloride, benzene trisulfonyl chloride, tricaprylyl chloride, butanetriacyl chloride, pentatricolyl chloride, glutaryl chloride, adipoyl chloride, maleoyl chloride, cyclopropanetriacyl chloride, cyclobutane trisulfonyl chloride, cyclobutane tetrasulfonyl chloride, cyclopentane diacyl chloride, cyclopentane triacyl chloride, cyclopentane tetraacyl chloride, cyclohexane diacyl chloride, cyclohexane triacyl chloride or cyclohexane tetraacyl chloride, and the concentration of the oil-soluble monomer is 0.01-4.0 wt%.

6. The dissipative particle dynamics method for studying interfacial polymerization reaction mechanism of composite membrane according to claim 1, wherein the second step comprises the following steps:

(1) coarse granulating each substance in the system according to the chemical structures of the solvent and the monomer in the water phase and the oil phase, and defining DPD beads of different types;

(2) the types of the beads are set by using a Materials Visualizer module of Materials Studio software, and corresponding DPD beads are used for constructing DPD molecular models of water molecules, water-soluble monomer molecules, organic solvent molecules and oil-soluble monomer molecules.

7. The dissipative particle dynamics method for studying interfacial polymerization reaction mechanism of composite membrane according to claim 1, wherein the third step comprises the following steps:

(1) building a cubic box by using Materials Studio software, averagely dividing the box into an upper layer and a lower layer, setting the upper layer as an organic phase in the interfacial polymerization reaction process, placing an organic solvent and an oil-soluble monomer, setting the lower layer as a water phase in the interfacial polymerization reaction process, and placing water molecules and a water-soluble monomer;

(2) the number of water molecules, water-soluble monomer molecules, organic solvent molecules, and oil-soluble monomer molecules is determined by the monomer concentration required for the interfacial polymerization reaction.

8. The dissipative particle dynamics method for studying interfacial polymerization reaction mechanism of composite membrane according to claim 1, wherein the fourth step is as follows:

the Flory-Huggins parameters of the beads are obtained by molecular dynamics simulation or through a reference document, and then the interaction force parameters among the coarse-grained beads are calculated according to a DPD theory.

9. The dissipative particle dynamics method for studying interfacial polymerization reaction mechanism of composite membrane according to claim 1, wherein the fifth step is as follows:

(1) selecting a Geometry Optimization task in a Mesocite module to carry out structural Optimization on the constructed interface aggregation system;

(2) carrying out DPD simulation on the interface polymerization system DPD model obtained by the construction method in the third step and the acting force parameter obtained in the fourth step by utilizing a Mesocite module of Materials Studio software to obtain a stable equilibrium state interface polymerization structure;

(3) and outputting and storing a motion track file and a related calculation file of each bead in the DPD simulation, wherein the related files refer to an interaction energy file, a concentration file, a density file, a radial distribution function file, a mean square displacement file and a mutual distance file.

10. The dissipative particle dynamics method for studying interfacial polymerization reaction mechanism of composite membrane according to claim 1, wherein the sixth step is as follows:

(1) outputting the structure of the interface polymerization system DPD model obtained in the fifth step when the model reaches a stable equilibrium state, and observing the motion tracks of all DPD beads;

(2) according to a motion track file and a related calculation file of beads in which water-soluble monomers and oil-soluble monomers react with each other, making a fast graph which reflects a track evolution graph of a structure of a polymer layer formed by the interface polymerization reaction of the two monomers at an interface along with time, calculating an evolution graph of the concentrations of the water-soluble monomers and the oil-soluble monomers in the interface polymerization layer along with time, and inspecting the concentration distribution of the two monomers near the interface polymerization layer at different times;

(3) through the analysis, the factors determining the structure and the performance of the polymer and the influence rule thereof in the interfacial polymerization reaction process are analyzed.

Technical Field

The invention belongs to the field of high-performance membrane materials, and particularly relates to a dissipative particle dynamics method for researching a composite membrane interfacial polymerization reaction mechanism by utilizing a computer simulation technology.

Background

With the occurrence of the problems of water resource shortage, increasingly serious water pollution and the like, the membrane separation technology is used as one of economic and efficient technologies for sewage treatment, seawater desalination and brackish water desalination, and has wide market application prospect. The membrane material, as the core of the membrane separation technology, will directly affect the membrane separation performance and the application of the membrane technology. The preparation of high-performance membrane materials is a hot spot of continuous development and research in the industry and academia. Currently commercialized reverse osmosis membranes, nanofiltration membranes and organic solvent resistant nanofiltration composite membranes are generally prepared by interfacial polymerization of a water-soluble monomer in a water phase and a polybasic acid chloride monomer in an oil phase on the surface of a base membrane to form a polyamide selective separation layer. In the interfacial polymerization process, the monomer concentration, the reaction time and the structure of the base membrane are key factors influencing the performance of the finally prepared polyamide composite membrane. Although great progress has been made in the synthesis of novel membrane materials and in the modification of membrane materials, there is still insufficient research and explanation on the microstructure properties and mechanism of interfacial polymerization during the preparation of high-performance membrane materials. Therefore, the method is very important for researching the microstructure characteristics and mechanism in the process of preparing the high-performance composite membrane by the interfacial polymerization reaction.

At present, widely applied experimental characterization methods and detection methods (such as SEM, TEM, AFM and the like) are difficult to meet the requirements of quantitatively analyzing the surface microscopic characteristics and the dynamic change process of the water-soluble monomer in the interface polymerization process at the atomic molecular level, and are also difficult to explain the interface polymerization mechanism at the molecular atomic level. Therefore, it remains a great challenge to experimentally precisely control the structure and performance of a polymeric composite membrane. Compared with experimental means, computer simulation can help researchers understand possible influences of interfacial polymerization reaction processes, clear monomer/solvent concentrations, structures, chemical properties and the like on polymerization reactions from a microscopic view angle, and is a powerful means for researching interfacial polymerization reaction mechanisms of separation membranes. The Dissipative Particle Dynamics (DPD) simulation technology can make up the defects of experimental means, provides a new thought for deeply researching thermodynamic and kinetic influence factors of interfacial polymerization reaction of a composite membrane separation layer, and provides a reliable theoretical basis for exploring interfacial polymerization reaction mechanisms so as to further improve the interfacial polymerization process and obtain high-performance membrane materials.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for researching and researching thermodynamic and kinetic influence factors of interfacial polymerization reaction of a composite membrane separation layer from a microscopic angle by using Materials Studio calculation software and DPD simulation so as to develop the understanding of the interfacial polymerization reaction mechanism of a high-performance separation membrane.

The purpose of the invention is realized by the following technical scheme:

a dissipative particle dynamics method for researching a composite film interfacial polymerization reaction mechanism comprises the following steps:

determining various substance components and chemical structures thereof in a water phase and an oil phase of an interfacial polymerization system, wherein the water phase comprises water-soluble water and water-soluble monomers, and the oil phase comprises an organic solvent and oil-soluble monomers;

step two, respectively constructing a DPD model of the water phase solvent and the water-soluble monomer molecules and a DPD model of the organic solvent and the oil-soluble monomer molecules in the oil phase;

step three, establishing a DPD structural model of an interfacial polymerization reaction system consisting of a water phase and an oil phase;

step four, calculating interaction parameters among all DPD beads, namely conservative force parameters;

fifthly, carrying out DPD simulation by using Materials Studio software, and obtaining a motion track file and a related calculation file of each DPD bead after the system is balanced;

and step six, observing the structural characteristics of the separation layer of the composite membrane generated by the interfacial polymerization reaction according to the simulation result, and researching influence factors determining the performance of the separation layer in the interfacial polymerization process by combining the calculation file.

Further, the water-soluble monomer is one or more of piperazine, 2-methylpiperazine, 2, 5-dimethylpiperazine, 4-aminomethylpiperazine, 2, 5-diethylpiperazine, alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin, delta-cyclodextrin, p-phenylenediamine, m-phenylenediamine, trimesamine, diaminotoluene, ethylenediamine, propylenediamine, xylylenediamine, 1, 3-diaminocyclohexane or 1, 4-diaminocyclohexane, and the concentration of the water-soluble monomer is 0.01 to 8.0 wt%.

Further, the water-soluble monomer is preferably piperazine, m-phenylenediamine or cyclodextrin.

Further, the organic solvent in the oil phase is one or more of n-hexane, cyclohexane, heptane, octane, naphtha, Isopar-E, Isopar-G, Isopar-L or mineral oil.

Further, the oil-soluble monomer in the oil phase is a polyacyl chloride monomer, and comprises one or more of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, benzenetrisulfonyl chloride, tricaprylyl chloride, butanetriacyl chloride, pentatriacyl chloride, glutaroyl chloride, adipoyl chloride, maleoyl chloride, cyclopropanetriacyl chloride, cyclobutanetriacyl chloride, cyclobutane tetracoyl chloride, cyclopentanedioyl chloride, cyclopentane triacyl chloride, cyclopentane tetracoyl chloride, cyclohexane diacyl chloride, cyclohexane triacyl chloride or cyclohexane tetracoyl chloride, and the concentration of the oil-soluble monomer is 0.01-4.0 wt%.

Further, the specific steps of the second step are as follows:

(1) coarse granulating each substance in the system according to the chemical structures of the solvent and the monomer in the water phase and the oil phase, and defining DPD beads of different types;

(2) the types of the beads are set by using a Materials Visualizer module of Materials Studio software, and corresponding DPD beads are used for constructing DPD molecular models of water molecules, water-soluble monomer molecules, organic solvent molecules and oil-soluble monomer molecules.

Further, the third step comprises the following specific steps:

(1) building a cubic box by using Materials Studio software, averagely dividing the box into an upper layer and a lower layer, setting the upper layer as an organic phase in the interfacial polymerization reaction process, placing an organic solvent and an oil-soluble monomer, setting the lower layer as a water phase in the interfacial polymerization reaction process, and placing water molecules and a water-soluble monomer;

(2) the number of water molecules, water-soluble monomer molecules, organic solvent molecules, and oil-soluble monomer molecules is determined by the monomer concentration required for the interfacial polymerization reaction.

Further, the fourth step is as follows:

the Flory-Huggins parameters of the beads are obtained by molecular dynamics simulation or through a reference document, and then the interaction force parameters among the coarse-grained beads are calculated according to the DPD theory.

Further, the step five is specifically as follows:

(1) selecting a Geometry Optimization task in a Mesocite module to carry out structural Optimization on the constructed interface aggregation system;

(2) carrying out DPD simulation on the interface polymerization system DPD model obtained by the construction method in the third step and the conservative force parameter obtained in the fourth step by utilizing a Mesocite module of Materials Studio software to obtain a stable equilibrium state interface polymerization structure;

(3) and outputting and storing a motion track file and a related calculation file of each bead in the DPD simulation, wherein the related files refer to an interaction energy file, a concentration file, a density file, a radial distribution function file, a mean square displacement file and a mutual distance file.

Further, the sixth step is as follows:

(1) outputting the structure of the interface polymerization system DPD model obtained in the fifth step when the model reaches a stable equilibrium state, and observing the motion tracks of all DPD beads;

(2) according to a motion track file and a related calculation file of beads in which water-soluble monomers and oil-soluble monomers react with each other, making a snapshot to reflect a track evolution diagram of a structure of a polymer layer formed by the interfacial polymerization reaction of the two monomers at an interface along with time, calculating an evolution diagram of the concentrations of the water-soluble monomers and the oil-soluble monomers in the interface polymerization layer along with time, and inspecting the concentration distribution of the two monomers near the interface polymerization layer at different times;

(3) through the analysis, the factors determining the structure and the performance of the polymer in the interfacial polymerization reaction process and the influence regulation thereof are analyzed.

Aiming at the interfacial polymerization reaction process of the composite membrane separation layer, the DPD simulation is combined with experimental research, the influence of each factor on the structure and the performance of the composite membrane separation layer is researched, the reaction mechanism of the interfacial polymerization process is explored from a microscopic angle, and a theoretical basis is laid for obtaining a high-performance membrane material by improving the interfacial polymerization process.

The DPD simulation method disclosed by the invention is used for researching the interfacial polymerization reaction mechanism of the composite film separation layer, and compared with the traditional method, the DPD simulation method has the following remarkable advantages: (1) the structure and performance of a composite membrane separation layer formed by interfacial polymerization reaction can be researched on a mesoscale, and the influence mechanism of each factor in the interfacial polymerization reaction process can be researched; (2) a dynamic visual effect diagram of the interfacial polymerization reaction can be provided, which is beneficial to further and deeply knowing the mechanism of the interfacial polymerization reaction; (3) the research result makes up the defects of experimental means, and the forming process of the composite membrane separation layer and the influence factors of the structure and the performance of the composite membrane separation layer can be visually and vividly observed from a microscopic angle; (4) the method can be applied to the fields of chemical, environmental and life sciences related to membrane material preparation, water treatment and the like.

Drawings

FIG. 1 is a schematic diagram of DPD coarse granulation model of solvent, gel film material and monomer in hydrogel phase and organic phase in interfacial polymerization process in example 2;

FIG. 2 is a graph showing the distribution of each substance in the aqueous phase and the oil phase in the initial state of interfacial polymerization in example 2.

Figure 3. example 2, the composite membrane separation layer formed by interfacial polymerization of PIP in the aqueous phase and TMC in the oil phase at equilibrium is shown.

Detailed Description

For better understanding of the present invention, the technical solution of the present invention is further described in detail with reference to the specific embodiments, but the present invention is not limited thereto, and modifications or equivalent substitutions may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.