Ethylene polymerization and polyethylene functionalization
Tutor / director / evaluatorD'agosto, Franck and Boisson, Christophe
Document typeMaster thesis (pre-Bologna period)
Rights accessOpen Access
Polyolefins have become ubiquitous and are large volume commodity materials. Of current interest is the preparation of speciality polymers incorporating polyethylene (PE), which often requires polymer chain-end manipulation. Ethylene polymerization by a neodymium catalyst in conjunction with n-butyloctylmagnesium (BOMg) is based on a reversible chain-transfer between Nd (where PE chains grow) and Mg (where PE chains rest). Using a large BOMg/Nd ratio for ethylene polymerization leads to magnesium-bound PE chains (PE-Mg-PE). We showed PE-Mg-PE is a precursor to end functionalized PE (PE-X) the potential applications of which include the design of macromolecular architectures based on PE. A drawback of the polymerization system is the optimum operating temperature (80°C) which is sufficient to produce only low molecular weight PE. This study aims to develop a polymerization system in which reversible chain transfer occurs at a high operating temperature. A catalyst system based on a dichloro-iron(II)-2,8-bis(imino)quinoline complex, [(BIQ)FeCl2], is a suitable candidate due to i) satisfactory polymerization behaviour above 100°C when activated by methylaluminoxane (MAO) and ii) the potential for chain transfer with ZnEt2, established previously with Fe based catalysts. [(BIQ)FeCl2]) was assessed for ethylene polymerization in the absence and in presence of ZnEt2.