Synthesis And Application Of Hollow Microporous Polymer Microspheres

Microporous organic polymer is a kind of material which contains a large specific suface area and huge number of porous structure whose size is less than 2 nm. Due to its chemical and physical stability, super high specific surface area, low density skeleton, the application research of microporous organic polymer on gas storage, adsorption, separation, catalysis, optoelectronics and other fields has attracted people’s wide attention.There exist a large number of synthetic routes by which a wide range of functionalities can be introduced. In this study, we described a hollow microporous polymer microspheres(HMPMs), studied the synthetic method to prepare them and also introduced magnetic nanoparticles and quantum dot semiconductor crystals into HMPMs, thus bifunctional magnetic and fluorescent composite microspheres were prepared.Firstly, monodispersed silica nano–microspheres were synthesized through a classical St?ber method and modified with silane coupling agents(i.e. γ-MPS). The effects of different experimental conditions and material ratio on silica’s particle size and its distribution were studied. The optimized condition is chosed to synthesize monodisperse silica nano–microspheres whose average particle sizes are 178 nm: 330 m L of ethanol, 8 m L of anmonia, and 20 m L of TEOS, 4 m L of γ-MPS. Transmission electron microscopy(TEM) shows that the silica nano–microspheres have good spherical shape and monodispersity. Infrared(FT?IR) demonstrates that γ-MPS is successfully grafted on silica nano–microspheres’ surface which lead to a good dispersion in both toluene and styrene.Sencondly, monodispersed silica nano–microspheres with diameter of 178 nm were used as templates, a series of Si O2/(PS?DVB) composite microspheres under different polymerization conditions had been synthesized with styrene(St), divinylbenzene(DVB) as monomers, potassium persulfate(KPS) as initiator via in situ emulsion polymerization method. It turns out that different amounts of DVB have little influence on Si O2/(PS?DVB) composite microsphere’s particle size and its distribution but have great influence on its structure, when the content of DVB reaches 5 %, it can form a relatively symmetrical core-shell structure. Furthermore, FDA was used as an external crosslinker to fabricate hypercrosslinked Si O2/(PS?DVB) composite microspheres by a simple one-step Friedel-Crafts reaction. Inorganic cores were removed by using HF to obtain the HMPMs. The result of nitrogen adsorption-desorption isotherm indicates that HMPMs’ shell combined massive microporous and a certain amounts of mesoporous and macroporous features in one unit.The as-prepared HMPMs’ BET surface area can be as high as 778.07 m2·g-1 when the DVB content is 0.5 %. The BET surface area decreases with the increasing DVB content.In order to realize the function of HMPMs, ferriferrous oxide and Cd Se/Zn S quantum dots were chosed as magnetic and fluorescent sources respectively to prepare magnetic fluorescent bifunctional HMPMs. Magnetic nanoparticles were loaded into HMPMs through in situ co-precipitation method and QDs were loaded by swelling method. XRD and PPMS-9T comprehensive physical properties tester indicates the exsistence of Fe3O4 particles in HMPMs, and the magnetic fluorescent HMPMs are superparamagnetic, whose saturation magnetizations are up to 46.337 eum/g. Besides, saturation magnetizations of the magnetic fluorescent HMPMs increase with the inreasing concentration of iron ion. In addition, the magnetic fluorescent HMPMs have a quick response under external magnetic field. Fluorescence microscopy(FM) observes that magnetic-fluorescent HMPMs present green fluorescence. Both swelling system and swelling time have influence on magnetic fluorescent HMPMs’ fluorescence intensity. UV?visible spectrophotometer(UV?vis) tested the loading capacity of HMPMs with different pore size distribution under the same concentration of QDs, results show that loading capacity of magnetic fluorescent HMPMs whose DVB content is 0.5 % reaches 1.485×10-5 mol/L. The magnetic fluorescent microspheres are expected to be applied in area of biomedicine and heavy metal ion detection.