Method for forming exfoliated clay-polyolefin nanocomposites

Abstract

A method for forming a nanocomposite by olefin polymerization in which at least one cation-exchanging layered load material, selected from the group consisting of cation-exchanging, layered inorganic silicates and cation-exchanging, layered compounds other than silicates, is treated with acid to disrupt its layered structure and is combined with a catalyst that becomes activated for olefin polymerization when in contact with the acid-treated filler. An olefin is contacted by the activated catalyst—filler combination either (a) in the absence of an alkylaluminum co-catalyst or (b) with an alkylaluminum co-catalyst when the activatable catalyst is a polyalkylmetal compound, to form a nanocomposite containing polyolefin and the acid-treated filler. In a particular embodiment, sufficient filler is used to constitute at least 30 weight % of the nanocomposite to prepare a highly loaded nanocomposite masterbatch. A predetermined amount of one or more olefinic polymers can then be blended with the masterbatch to obtain a nanocomposite having a desired amount of loading. The filler is preferably clay, exemplified by montmorillonite. The catalyst is preferably a non-metallocene catalyst, most preferably a nickel complex bearing an α-iminocarboxamidato ligand.