Preparation And Properties Of Metal Organic Coordination Polymer Wall Material Microcapsules

Acid rain is one of the most important factors causing building facades corrosion damage and it greatly shortens the life of the building’s exterior. Our country and around the world needs to spend a lot of resources to repair the exterior of the building every year. If acid rain-sensitive self-healing microcapsules applying to building facades, when acid rain causing building facades damage, it can response to acid rain to release repair agent to repair the crack. It can improve the life of the building’s exterior greatly and produce a huge economic and social benefit.In this thesis, acid rain as a trigger-source, acid rain–trigger microcapsules were designed and prepared. ZIF-8 particles were embedded in microcapsule shell materials, which would decompose in acidic solution. Microcapsules can exist in alkaline aqueous solution and organic solvents stably. But, microcapsule shell will be broken in acidic solution, because the ZIF-8 particles embedded in microcapsule shell materials responds to H+ leading to decompose. It can release repair agent to achieve chemical triggered after shell broken.PMMA-(ZIF-8)/E51 and PS-(ZIF-8)/DCPD microcapsules were synthsised which shell materials were polymethyl methacrylate(PMMA) and polystryene(PS) embedded with ZIF-8 particles containing core material epoxy E51 and dicyclopentadiene(DCPD) respectively. The preparation parameters emulsifier and its dose, stirring rate, emulsifying time, react temperature were studied to explore the optimal synthesis scheme. The optimal synthesis scheme of PMMA-(ZIF-8)/E51 microcapsule was as follows: PVA as emulsifier, stirring rate 750 rpm, emulsifier dose 5%, react temperature 39℃, react time 5 h. The optimal synthesis scheme of PS-(ZIF-8)/DCPD microcapsules was as follows: PVA as emulsifier, stirring rate 600 rpm, emulsifier dose 3%~5%, emulsifying time 15~20min, react temperature 39℃, react time 5 h. Microcapsules have average particle size 15~20μm, good dispersion, and shells were embedded with ZIF-8 particles.Use SEM to observe the appearance of microcapsules, FTIR to analyze the chemical structure of microcapsules, TGA to analyze the thermal stability of microcapsules. They can prove the core materials were coated by microcapsules absolutely, and ZIF-8 particles were embedded in microcapsule shells. Micro-mechanical test on nanoindenter shows that the microcapsules have good mechanical property. In the simulated acid rain test, two microcapsules show a good response to acid rain to achieve chemical trigger.