Controlled radical polymerization of vinyl acetate in the presence of mesoporous silica supported TiCl4 heterogeneous catalyst

Transition metals have recently been used to catalyze controlled radical polymerization of styrene and acrylates. A variety of transition metals such as copper, ruthenium, iron,cobalt, titanium, and nickel have been successfully employed in ATRP. In this paper, we report the polymerization of vinylacetate with the heterogeneous catalysts of TiCl4. The mesoporous silica particles have been synthesized and used to make active heterogeneous TiCl4 catalyst to control thesequences of the growing chain in a controlled free radical polymerization of vinyl acetate. A small amount of DMF hasbeen used as a ligand to activate the process. A more linear polymer was formed from the heterogeneous TiCl4 on themesoporous SPB compared to MCM-41. The polymerizationstarts from the immobilized and fixed sites of the catalyst located on the surface or on the pores of this catalyst. The twocenters in this polymerization produced two but different sequences of the polymer chain, each sequence indicating a different glass transition temperature with different d-spacing related to its own crystallinity.