Design of new poly(ethylene) based materials by coordination (co)polymerization of macromonomers with ethylene
Résumé
The present work discusses first the homopolymerization of omega-allyl, omega-undecenyl or omega-vinylbenzyl polystyrene (PS) macromonomers in the presence of selected early or late transition metal catalysts. Homopolymerization degrees were found to depend on the type of catalyst, the terminal double bond, the polymerization temperature and the concentration of the various species. Higher molar masses were reached at low temperatures and low catalyst and cocatalyst concentrations. Best results were obtained with the constrained geometry catalyst (CGC)-Ti. The same PS macromonomers were copolymerized with ethylene in the presence of the VERSI-POL (TM) catalyst to design a new type of poly(ethylene) based graft copolymer. The macromonomer weight percent content decreases with increasing ethylene pressure whereas the molar mass of the copolymer increases with ethylene pressure. The PS macromonomer content as well as the molar mass of the copolymer can be still increased by using alpha,omega-difunctional PS macromonomers. The dilute solution and solid-state behavior of these copolymers were examined and compared to those of poly(ethylenes) prepared under the same conditions.