Cationic polymerization of dienes VIII: Is the elimination of cross-linking by a bulky electron donor a general behavior in the presence of aluminium trichloride?

摘要

Previous works on the polymerization of I _3-pentad_ene initiated by aluminium trichloride in non polar solvent at room temperature in the presence of bulky electron donor (ED) as tri-p-tolylamine have highlighted a stabilization of the polymerizing actives centres by ED, which allowed a reduction of some side reactions and the formation of more precisely defined polypentadienes than ever by cationic polymerization in non polar medium. The aim of this research was to investigate the role of bulky EDs such as tri-p-tolylamine and similar compounds in polar medium in order to obtain if possible a complete contro] of the polymerization of isoprene and I,3-pentadiene, The beneficia] effect of tri-p-tolyl_amine was shown in the case of isoprene polymerization at room temperature, with an important reduction of the cross-linked fraction for long reaction times and strong reduc_tion of termination reactions. At _30 °C in the presence of tri-p-tolylamine, polypentadi_enes more controlled than in non polar solvent could be obtained, with a nearly complete elimination of the cross-linked fraction, while keeping the microstructure approximately constant.