Ring-opening polymerization of cycloolefins with MgCl2

Until now polymerization catalysis was linked to transition metal chemistry with only few exceptions. However, in our work we will show that the main group metal salt MgCl2 can give rise to oligomerization and polymerization of olefins. Since the late 1960s MgCl2 has been used as support material for commercial Ziegler-Natta catalysts in many variations. Although the influence of this 'inert' support on the structure and properties of the resulting polymers is known, investigations of the reactivity of MgCl2 with olefins are rare. Surprisingly MgCl2 polymerizes strained olefins like norbornene, norbornadiene, 5,6-dichloronorbornene and bistrifluoromethyltricyclo[4.2.2.0]decatriene in high yield to high molecular weight products. The polymers are characterized by FT-IR, NMR, size exclusion chromatography (GPC) and thermoanalytical methods. The properties and structure of these polymers correspond to those prepared by ring-opening metathesis polymerization (ROMP). The characterization of different MgCl2 phases is carried out by the use of powder diffraction measurements, electron microscopy, measurements of the specific surface (BET), simultaneous thermal analysis (STA), and atomic absorption spectroscopy (AAS).