THE EFFECT OF CYCLIC OLEFINS ON THE PHILLIPS CATALYST: opening the way towards functional polyolefins

In modern world imagining a life without plastics is nearly impossible. Today almost everyone, everywhere and everyday comes in contact with objects having at least a component made by plastic materials. Plastics have brought massive benefits in human life, however, the general perception of plastics is rather negative. This is particularly true for polyolefins, which are by far the most diffuse plastics. The main problem is that the polyolefins applications are many, but often limited in time: the life cycle of polyolefin is very short, normally no more than a year. The synthesis of new polymers with specific functions is one of the key targets in the new plastic economy. In this respect, cyclic olefin copolymers (COCs) are high-performance alternatives to traditional polyolefin commodities for a broad range of applications. They are obtained through the catalytic co-polymerization of ethylene with cyclic olefins. Their physical properties, such as melting point, crystallinity and glass transition, can be tuned by changing the structural and microstructural features of the macromolecular chains, which is affordable by selecting the right catalyst for their production. Relevant works in this field demonstrate that homogeneous Cr-based complex have this capability. In this Master Thesis work we performed a preliminary investigation to understand if the Cr-based heterogeneous Phillips catalyst is able to polymerize cyclic olefins, in particular norbornene (NB) and norbornadiene (NBD). The choice of the Phillips catalyst is dictated by its great industrial relevance and versatility, which is however counterbalanced by a poor understanding of its basic functioning. The interaction and reactivity of NB and NBD with the Cr/SiO2 catalysts, in both its oxidized (Cr(VI)/SiO2) and reduced (Cr(II)/SiO2) forms, were investigated at a molecular scale by means of FT-IR and DR UV-Vis spectroscopies.