Branched polyolefin synthesis

An improved process for the anionic polymerization of at least one vinylic monomer to form a branched polymer, comprising contacting, in the presence of an anionic initiator:

• (i) one or more anionically polymerizable vinylic monomers having the formula CH2=CYZ, and
• (ii) an anionic polymerization chain terminating agent of formula CH2=CZ-Q-X
• wherein:
• Q is selected from the group consisting of a covalent bond, R, C(O), RC(O);
• Y is selected from the group consisting of R, CO2R, CN, NR2;
• X is selected from the group consisting of halogen, RSO3;
• Z is selected from the group consisting H, R, CN;
• R is selected from the group consisting of unsubstituted and substituted alkyl, olefin, aryl, aralkyl, alkaryl and organosilicon groups, the substituents being the same or different and selected from the group consisting of carboxylic acid, carboxylic ester, hydroxyl, alkoxy and amino;
• wherein the improvement comprises obtaining higher yields of branched polymer, the polymer having dense branch upon branch architecture and polymerizable vinylic chain termini, employing steps I, III, VI and at least one of II, IV and V:
• I. reacting (i) with an anionic initiator in a first step;
• II. decreasing the ratio of (i) to anionic initiator toward 1
• III. adding (ii) optionally with some (i) in a second step;
• IV. selecting the rate of the (ii) addition, dependent on the reactivity of (ii);
• V. increasing the ratio of (ii) to anionic initiator toward 1;
• VI. increasing the conversion of (i), (ii) and olefinic end groups from 70 toward 100%;
• and
• VII. optionally, converting anionic-growing end groups into non-polymerizable end groups.