Preparation of silica/polyacrylamide/polyethylene nanocomposite via in situ polymerization

SiO2/polyacrylamide (PAM) composite was prepared via the polymerization of acrylamide in the presence of silica sol in water/hexane emulsion, and pure SiO2 was also prepared without the use of acrylamide in the same way. Field emission scanning electron micrographs (FESEM) showed that PAM covered the silica nanoparticles to form SiO2/PAM nanospheres, which loosely agglomerated to form SiO2/PAM secondary particles, while SiO2 secondary particles were made up of tightly agglomerated silica nanoparticles. Metallocene catalyst was then immobilized over SiO2 and SiO2/PAM respectively to prepare supported metallocene catalyst for ethylene polymerization. Transmission electron micrographs (TEM) showed that support particles broke up to smaller particles and even nanoparticles in polyethylene (PE) matrix when the support particles were the fragile SiO2/PAM secondary particles, which shows a novel way to prepare silica/polyacrylamide/polyethylene nanocomposite.