PE/OMMT nanocomposites catalyzed by the OMMT-intercalated Et[Ind]2ZrCl2 in slurry polymerization: Effects of organic solvent on ethylene polymerization behaviors and the nanocomposite structures

In situ intercalative polymerization for ethylene monomers was carried out to produce PE-based hybrids through a slurry polymerization method. In this approach, organic solvent for olefin polymerization was found to be one of the most significant factors for the dispersion of the OMMT-intercalated Et[Ind]2ZrCl2 catalysts, which determines that whether olefin monomers polymerize is in a well-defined confinement environment or not. Understanding the olefin polymerization occurring in between the nanoscale silicate layers of OMMT as well as the corresponding structure of OMMT in an organic polymerization solvent is a critical step toward tailoring and characterizing nanocomposites formed by OMMT in a polyolefin matrix. As we know, the Et[Ind]2ZrCl2 catalyst and MAO are both better dissolved in toluene than that in hexane because of the larger polarity of toluene. Thus, in hexane the active sites of the OMMT/Et[Ind]2ZrCl2 catalyst exist in the silicate layers of OMMT and the PE chains grow in the middle of them, while in toluene the active specimens are exposed in the gel formed by the OMMT-intercalated catalyst with MAO, which cause that the PE chains propagated in the mixture liquids. Consequently, when hexane is selected as the polymerization solvent, the formed PE-based nanocomposites have a good dispersion of OMMT and the nanofiller content (TGA measurement residue at 600°C) is thus higher (>7.0 wt %). However, in toluene, most of the silicate layers of OMMT are agglomerated in the PE matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011