Nitriles as Functionalization and Coupling Agents for Polyolefins Obtained by Coordinative Chain Transfer Polymerization

Coordinative chain transfer polymerization (CCTP) of ethylene and its copolymerization with 1,3‐butadiene is conducted in toluene at 80 °C using a combination of {(Me2Si(C13H8)2)Nd(μ‐BH4)[(μ‐BH4)Li(THF)]}2 (1) metal complex and various organomagnesium compounds used as chain transfer agents including n‐butyl‐n‐octyl‐magnesium (BOMAG), n‐butyl‐mesityl‐magnesium (n‐BuMgMes), n‐butyl‐magnesium chloride (n‐BuMgCl), n‐pentyl‐magnesium bromide (n‐C5H11MgBr), pentanediyl‐1,5‐di(magnesium bromide) (PDMB) and isobutyl‐magnesium chloride (i‐BuMgCl). Kinetics and performance in terms of control of the (co)polymerization are comparatively discussed particularly considering the presence of ether and the nature of the organomagnesium compounds employed. Taking advantage of the well‐known reactivity between nitrile and molecular organomagnesium compounds, the functionalization of the chains is further carried out by deactivation of the polymerization medium with benzonitrile or methoxybenzonitrile compounds leading to ketone ω‐functionalized chains. The success of the functionalizations is extended to coupling strategies using dinitrile reagents and to the functionalization of high molar mass ethylene butadiene rubber (EBR). Polyolefins such as polyethylene and poly(ethylene‐co‐butadiene) are synthesized by coordinative chain transfer polymerization (CCTP). The catalytic system is based on a combination of {(Me2Si(C13H8)2)Nd(μ‐BH4)[(μ‐BH4)Li(THF)]}2 metal complex and various organomagnesium compounds used as chain transfer agents. Nitrile compounds are implemented for the chain end functionalization and coupling reaction.