Synthesis And Functionalization Of Crosslinked Polystyrene Microspheres

With functional polymer microspheres depth application in microspheres surfaces further response, as the material with some specific functions grafted onto the surfaces of microspheres, they have new functions. This category produced unique potential applications of the high-functional materials prospects. The synthesis method of functional polymer microspheres is heterogeneous system copolymerization. This copolymerization mainly occurs by emulisifier-free emulsion polymerization or dispersion polymerization. Furthermore, the approach of realization the functions also include the microsphers surface modification.Two methods, dispersion polymerization and emulisifier-free emulsion polymerization, were used for preparing crosslinked polystyrene microspheres with reactive chlorine atom on their surfaces. Chlorine contents on the microsphere surfaces were characterized by X-ray photoelectron spectrometer (XPS). The results showed that there were much chlorine atoms on the microsphere surfaces through adding a small amount of p-Chloromethylstyrene (CMSt) on emulisifier-free emulsion polymerization of styrene. And the effect factors of two polymerization methods have been studied. In dispersion polymerization, the dynamics radius (Rh) of the crosslinked microspheres reduce with the increase of 2,2'-azobisisobutyronitrile (AIBN) or polyvinylpyrrolidone (PVP) concentration, and increase with the increased usage of CMSt. While in other conditions unchanged, Rh distribution is narrowest in the percentage concentration of 4% PVP quality. In emulisifier-free emulsion polymerization, at given temperature, adding a certain amount of co-solvent acetone can attain high polymerization conversion rate in a relatively short time. In the same conditions, with the rise of reaction temperature, the reaction could be reached response destination in a relatively short time. Within a certain concentration, the Rh of the crosslinked microspheres reduce with the increase of potassium persulfate (KPS) concentration and the increase of acetone usage.N-isopropylacrylamide (NIPAAm) was initiated through atom transfer radical polymerization (ATRP) with the crosslinked polystyrene microspheres with much reactive chlorine atom on the surfaces as macroinitiator and PMDETA as ligand and CuCl as catalyst and the grafted poly (N-isopropylacrylamide) (PNIPAAm) chain was introduced onto the surfaces of the crosslinked polystyrene microspheres. The microspheres show temperature sensitivity. The properties of PNIPAAm-g-PSt, such as structure, property, morphology and diameter distribution were characterized by Fourier Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC), Scanning Electron Microscopy (SEM),...