Patent ID: 7132488

Claim:
A process for the preparation of homo- and copolymers of isobutene by cationic polymerization of isobutene or mixtures of isobutene with ethylenically unsaturated comonomers in the presence of an initiator system comprising: i) a Lewis acid selected from covalent metal-halogen compounds or covalent semimetal-halogen compounds, ii) at least one aprotic organic compound I having at least one functional group FG of the formula FG where X is selected from halogen, C 1 –C 6 -alkoxy or C 1 –C 6 acyloxy, R 1 is hydrogen or methyl and R 2 is methyl, with R 1 or the moiety to which the functional group FG is bonded, forms a C 5 - or C 6 -cycloalkyl ring, or is hydrogen when the functional group FG is bonded to an aromatic or olefinically unsaturated carbon atom, which, under polymerization conditions, forms a carbocation or cationic complex with the Lewis acid, wherein the organic compound I is selected from compounds of the formula I-A, I-B, I-C, or I-D: where X has the abovementioned meanings, n is 1, 2, 3, 4 or 5, R 3 , R 4 and R 10 , independently of one another, are each hydrogen or methyl, R 5 , R 6 and R 7 , independently of one another, are each hydrogen, C 1 –C 4 -alkyl or a group CR 3 R 4 X, where R 3 , R 4 and X have the abovementioned meanings, and R 8 is hydrogen, methyl or the group X and R 9 and R 9, are each hydrogen or the group X, in an organic solvent which is inert to the Lewis acid, wherein the initiator system additionally comprises iii) at least one nonpolymerizable, aprotic organosilicon compound II having at least one Si—O bond.