Immobilization of Late Transition Metal Catalyst on the Amino-functionalized Silica and Its Norbornene Polymerization

In this study, an amorphous silica was functionalized with aminosilane, N-((3-trimethoxysilyl)propyl)ethylenediamine (2NS) and the late transition metal catalysts including ((DME)NiBr2 and PdCl2(COD)) were subsequently immobilized on the func- tionalized amorphous silica for norbornene polymerization. Effects of the polymerization temperature, polymerization time, Al/Ni molar ratio, and type of co-catalyst on norbornene polymerization were investigated. Unsupported late transition metal catalysts did not show any activities for norbornene polymerization. However, the SiO2/2NS/Ni catayst with MAO system, with increasing polymerization temperature, increased the polymerization activity and decreased the molecular weight of the polynorbornene (PNB). Furthermore, the catalyst when increasing polymerization temperature caused the decrease in both the polymerization activity and molecular weight of PNB. This confirmed that the stability of SiO2/2NS/Ni at a high temperature was greater than that of SiO2/2NS/Pd. Also the longer polymerization time resulted in the higher conversion of norbornene for both catalysts. When the Al : Ni molar ratio was 1000 : 1, the highest activity (15.3 kg-PNB/ (µmol-Ni*hr)) but lowest molecular weight (Mn = 124,000 g/mol) of PNB were achieved. Also SiO2/2NS/Ni catalyst with borate/TEAL resulted in di- minishing the polymerization activity and molecular weight of PNB with increasing the polymerization temperature.