Construction ZIF-8 On The Surface Of PVDF Membrane Based On Membrane Permeation-assisted Seeded Method

Metal-Organic Framewokrs (MOFs) are a new crystalline porous material, which are composed by inorganic metal node and organic ligand, structure nano-sized tunnel construction through oriented design and organic ligands. MOFs have unique structural characteristics, which make them have a broad application prospect in catalysis, adsorption, separation, proton conduction, magnetic, photoelectric materials, and other fields. At present, the research focus on MOFs are no longer preparation and characterization of new structure metal, rather than tending to explore their practical application and the structure-activity relationship. Making MOFs onto membrane is one of the hot spots of studying MOFs application, MOFs Membrane not only is similar with molecular sieve membrane in chemical and thermal stability, but also its pore size can be designed, coming true the material transfer and separation in the hole.According to "molecular crystal engineering" theory and the polymer surface chemical method, making MOFs membrane in the polymer film surface by the second growth, this thesis research in polymer membrane surface functionalized modifications, the second growth and structure change of MOFs on membrane surface, exploring the controlled modification of the polymer film surface, aiming at developing MOFs new secondary growth method in polymer membrane surface and study its structural change. Full text research includes:The First Chapter Introduction It introduces the concept and features of MOFs materials simply, investigates and presents the preparation methods and the applications of current MOFs thin film materials comprehensively, states the growth of MOFs on the polymer membrane surface and the research progress of zeolite imidazole ester skeleton materials, and introduces the purpose and significance of the topic.The Second Chapter Some special groups can be employed to modify the PVDF membrane to made ZIF-8 growth more strongly on the PVDF film.1) Polymer poly-4-vinyl pyridine was grafted from the bromine-containing end groups hydrophilic modified polyvinylidene fluoride (PVDF) membrane, which acted as the substrate, via surface initiation activators generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron (XPS) and scanning electon microscopy (SEM) were empolied to characterized the surface composition, structures and morphology of the modified PVDF membranes. The results confirmed the successfully grafting of P4VP from the PVDF-Br surface and P4VP graft yield reached 0.82 mg/cm2.2) Use the small molecule silane coupling agent to treat hydrophilic PVDF membrane, then utilized ATR-FTIR, SEM to t characterize the the silane coupling agent grafted membrane respectively.The Third Chapter It is necessary to deposit a layer of ZIF-8 seed layer on the modified membrane's surface to control the ZIF-8 grow uniformly. We use zinc nitrate hexahydrate and 2-methylimidazole as raw materia to prepared imidazole skeleton zeolite crystals material ZIF-8 by solvothermal method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to characterized the product. The results show experimental and theoretical values of powder XRD ZIF-8 is in good agreement and ZIF-8 is a pure phase, uniform particle size of about 40nm.We deposited the ZIF-8 seed onto PVDF-g-P4VP modified membrane's surface under vacuum filtration method to research the preparation of a known concentration of the seed and the direct synthesis of seed material solution effects on the deposition uniformity of ZIF-8 seed in the modified membrane surface. In addition, we also studied decompression ultrafiltration and dip-copping two kinds of ZIF-8 seed deposition method effects on the deposition of ZIF-8 seed on the modified membrane surface. SEM and XRD analysis indicate the method of seed solution preparation have an effect on the deposition of ZIF-8 seed on the modified membrane surface and the seed crystal surface structure, deposition method is only impact on ZIF-8 seed crystal surface structure.The Four Chapter ZIF-8 seed grows in situ on modified PVDF membrane surface base on membrane permeation assistant crystal. The effect of the concentration of the metal salt solution and the ligand solution on both sides of the modified membrane, ligand solution alkaline, dense layer of modified PVDF membrane toward, the ratio of the ligand solution, and the different methods of making modified membrane on secondary growth of ZIF-8 on the film surface were investigated. XRD and SEM show ZIF-8 on modified PVDF membrane surface had a small particle diameter (about 100 nm) when the concentration of a solution of metal salt solution and ligand are low, and had a big particle diameter (about 5 microns) when the concentration of a solution of metal salt solution and ligand are high. When the density of the modified PVDF membrane layer toward the metal salts solution, the stronger the alkaline ligand side solution, the easier to get ZIF-8 on modified PVDF membrane density layer. When the density of the modified PVDF membrane layer is toward the ligand solution, no matter how to change the conditions can not get ZIF-8 on membrane density layer. When the metal ion salts were deposed on the modified PVDF membrane surface, regardless of PVDF-g-P4VP dense layer toward metal salt solution or ligand solution, can get ZIF-8 dense layer in PVDF-g-P4VP.