Preparation of nanosilica/polynorbornene nanocomposite by covalently immobilized silica-supported acetylacetonate palladium(II) dichloride catalyst

摘要

Covalently immobilized silica-supported acetylacetonate dichloride palladium(II) precatalyst is prepared by the reaction of silica particles grafted acetylacetonate ligand further exchange with [Et_4N] _2PdCl_4. The silica-supported catalyst is used in slurry polymerizations of norbornene (NB) to afford a highly productive NB addition polymerization system in combination with B(C_6F_5) _3 cocatalyst. It exhibits productivity of 84 kg of PNB (mol Pd) ~(-1) h~(-1) at the initial activity, and the catalyst deactivation kinetics in the early stage of polymerization are fitted well by the first-order deactivation kinetics. The obtained vinyl-type polynorbornene is confirmed to be nanosilica hybrid PNB nanocomposite by SEM, TEM with an energy dispersive spectrometer, TGA, and XRD. Covalently immobilized nanosilica-supported acetylacetonate dichloride palladium(II) precatalyst is prepared and used in slurry polymerizations of norbornene to afford nanosilica hybrid polynorbornene (PNB) nanocomposite in combination with B(C _6F_5)_3 cocatalyst. The productivity, the catalyst deactivation kinetics in the early stage of polymerization, and the mechanical and optical properties of polymeric composites are investigated.