| abstract |
The invention relates to a process for the preparation of polyisobutenes, in which at least 60 mol% of the polymer chains have at least one olefinically unsaturated end group, by cationic polymerization of isobutene or isobutene-containing monomer mixtures in the condensed phase, which is characterized in that the polymerization is carried out in the presence of an initiator system comprising DOLLAR A i) a Lewis acid selected from covalent metal chlorides and semimetal chlorides, DOLLAR A ii) at least one organic compound I having at least one functional group FG which forms a carbocation or a cationogenic complex with the Lewis acid under polymerization conditions, where FG is selected from acyloxy, alkoxy or halogen which are bonded to a secondary or tertiary, to an allylic or a benzylic C atom, DOLLAR A is carried out in a solvent which is inert to the Lewis acid, the Lewis acid in molar subs chuss, based on the functional groups FG, is used. |