Synthesis of polyethylene-layered silicate nanocomposites by intercalation polymerization

Nanocomposites based on PE and montmorillonite were prepared using traditional Ziegler-Natta catalysts, homogeneous metallocene catalysts, and montmorillonites of three types: nonmodified and modified by two different modifiers. It was shown that the type of montmorillonite and the method of its activation by various organometallic catalysts affect the degree of exfoliation of montmorillonite particles. A method for preparing nanocomposites was proposed which includes intercalation of a catalyst into the interlayer spacing of montmorillonite particles with subsequent polymerization of the monomer and exfoliation of montmorillonite particles under the action of the polymer being formed. The structure of the as-prepared nanocomposites was studied by X-ray diffraction, very cold neutron scattering, and transmission electron microscopy. It was found that, even though the content of the exfoliated montmorillonite is small, the elastic modulus of nanocomposites and their gas barrier behavior are dramatically improved as compared to the unfilled PE.