Cationic polymerization of dienes VII. New electron donors in the polymerization of 1,3-pentadiene initiated by aluminum trichloride in non-polar solvent

The aim of this research was to investigate new bulky electron donors (EDs) generating hindered active species in the cationic polymerization of 1,3-pentadiene initiated by AlCl₃ in pentane, in order to avoid or strongly reduce the reaction between the active species and the double bonds of the polymer which are responsible for side reactions. At room temperature, the polymerization in the presence of new ED, such as OPh₂, N(PhBr)₃, NPh₃ and SPh₂, allowed to obtain higher conversions and lower insoluble fractions than without electron donor. The formation of a complex ED/AlCl₃ was shown for each electron donor. However, in the case of NPh₃ and SPh₂, variations of the polymer microstructure demonstrated an interaction between active species and these EDs. Similar results were obtained at lower temperature (−10 °C). The beneficial effect of the presence of electron donors such as NPh₃ and SPh₂ demonstrated the validity of the concept of sterically hindered active species, but the polymerization was still uncontrolled.