Immobilization and Activation of a Single‐Site Chromium Catalyst for Ethylene Polymerization using MgCl2/AlRn(OEt)3 − n Supports

Summary: The effective immobilization and activation of a single‐site chromium catalyst for ethylene polymerization has been achieved using MgCl2/AlRn(OEt)3 − n supports, without the use of methylaluminoxane (MAO) or a borate activator. High catalyst activity and a spherical polyethylene‐particle morphology is obtained. Furthermore, the single‐site characteristics of the catalyst are retained, the narrow molecular weight distribution of the polymers obtained are apparent from gel permeation chromatography (GPC) and confirmed by rheological characterization. Shear frequency dependence of the storage modulus of (♦ and ▴) polyethylene (M w / M ₙ = 1.8–1.9) prepared using an immobilized Cr catalyst, compared to (▪) a reference polymer having M w / M ₙ = 4.1. image Shear frequency dependence of the storage modulus of (♦ and ▴) polyethylene (M w / M ₙ = 1.8–1.9) prepared using an immobilized Cr catalyst, compared to (▪) a reference polymer having M w / M ₙ = 4.1.