Coordination homopolymerization of omega-undecenyl poly(styrene-block-isoprene) macromonomers in the presence of CGC-Ti/MAO complexes
Résumé
This paper deals with the coordination homopolymerization of omega-undecenyl poly(styrene-block-isoprene) macromonomers. The synthesis of the macromonomers made use of an anionic living poly(styrene-block-isoprene) copolymer which is deactivated at low temperature by 11-bromo-1-undecene. The ability of these macromonomers to get involved in coordination homopolymerization in the presence of selected titanium catalysts was discussed. Special emphasis was given to the influence of polymerization temperature, macromonomer molar mass and concentration on the yield of homopolymerization and average degree of polymerization (DPn). in the presence of the CGC-Ti/MAO catalyst, macromonomer conversion, determined by SEC, was between 35 to 52 wt.-%, and DPn was between 5 to 14 depending upon the experimental conditions. However, as revealed by SEC/LS, the resulting comb-shaped polymers (PE-graft-(PI-block-PS), are characterized by sharp molar distributions. Increasing macromonomer molar mass, led to only a slight decrease Of DPn whereas conversion increased moderately. Other titanium catalysts such as CpTiCl3/MAO and Cp*TiCl3/MAO only caused macromonomer dimerization.