Characteristics and catalytic properties of supported titanocene catalyst for ethylene/1-octene copolymerization

Abstract

In the present study, the characteristics and catalytic properties of [t-BuNSiMe₂Flu]TiMe₂/dMMAO catalyst dispersed on various supports towards ethylene/1-octene copolymerization were investigated. First, the dMMAO was impregnated onto various supports such as SiO₂, SiO₂-TiO₂, and TiO₂. Then, copolymerization of ethylene/1-octene was conducted with and without the presence of supports in different solvent mediums such as toluene and chlorobenzene. It revealed that the SiO₂-TiO₂ support exhibited the highest activity among the other supports. The high activity observed for the SiO₂-TiO₂ support can be attributed to fewer interactions between the support and dMMAO as confirmed by XPS and TGA results. Moreover, ethylene polymerization was also conducted in this study. The activities of polymerization dramatically increased with the insertion of α-olefin due to the second comonomer effect. The slightly difference in the polymerization activities were apparently found in the supported system. It can be proposed that the different solvents can possibly alter the nature of catalyst in two ways; (i) changing the interaction between the support and cocatalyst and/or (ii) changing the form of active species i.e., active ion-pair and solvent-separated ion-pair as seen in the homogeneous system. However, there was no effect with regards to activity of the solvent mediums employed for the homogeneous system in ethylene/1-octene copolymerization. It is worth noting that the Ti-complex rendered pronouncedly high incorporation of 1-octene having the triblock (OOO) and diblock (EOO) copolymers. All the obtained polymers were characterized by GPC, DSC, and ¹³C NMR to determine the polymer properties and polymer microstructure.