Preparation and Characterization of Nano-SiO_2/PMMA Composite Particles by Emulsion Polymerization

The nano-SiO2/PMMA composite particles with core-shell structure were prepared by emulsion polymerization on the surface of nano-SiO2 using a polymerizable emulsifier(SE-10).The particles morphology and encapsulation effect were characterized by FTIR,TEM,XPS and TGA.The results indicated that the coupling agent MPTMS was grafted to the surface of modified nano-SiO2 and the spectra presented the composite structure of PMMA and nano-SiO2 without changing the structure of original nano-SiO2.The diameter of the composite particles was about 50-100 nm,the morphology had the core-shell structure with light outer part and dark inner part.The XPS analysis exhibited that the Si content on the surface decreased rapidly to 1.29% after nano-SiO2 was encapsulated by PMMA.After the nano-SiO2/PMMA composite particles were extracted by toluene,the Si content increased to 3.50%.Basing on the Soxhlet extraction experiments and TGA result,the ratio of PMMA to original nano-SiO2(fp),the grafting ratio of PMMA to original nano-SiO2(fr) and efficiency grafting ratio of PMMA(fe) were respectively about 95.8%,63.4% and 67.1%.