Polymerization-filled composites and nanocomposites by coordination catalysis

Polyolefinic microcomposites and layered silicate nanocomposites were prepared by the in-situ polymerization of ethylene (and alpha-olefin) via the so-called polymerization-filling technique. Various tillers with either basic, acidic, metallic or carbonaceous surface, as well as non-modified clays such as montmorillonite and hectorite, were first treated by trimethylaluminum-depleted methylaluminoxane before being contacted by a titanium or zirconium-based metallocene catalyst. The (nano)composite was formed by addition and polymerization of ethylene (and alpha-olefin). This technique makes possible the complete encapsulation of every filler particle within the (co)polyolefinic matrix ranging from thermoplastics to elastomers. The so-obtained (nano)composites, often coined as "homogeneous" (nano)composites, exhibit improved mechanical properties; as compared to more conventional melt blends for a same filler content.