METHOD FOR PREPARING ASYMMETRIC RADIAL POLYMERS

METHOD FOR PREPARING ASYMMETRIC RADIAL POLYMERS A method for preparing asymmetric radial polymers wherein the different polymeric arms are contacted sequentially with a non-polymerizable coupling agent. Contacting of the final step in the process, which frequently but not necessarily always will be the second step in the process, will be carried out in the presence of a polar compound suitable for increasing the amount of vinyl content in a conjugated diolefin polymer during polymerization thereof. The method used narrows the relative arm distribution of the several asymmetric radial polymers produced and significantly increases the amount of total product having the desired ratio of polymeric arms and accomplishes this objective in relatively short reaction time. Any non-polymerizable coupling agent known in the prior art to be useful in the production of asymmetric radial polymers may be used in the method of this invention but non- polymerizable coupling agents having from 3 to about 12 functional groups are most effective and non-polymerizable coupling agents having 2 or 3 functional groups are most preferred. Useful polar compounds are, generally, selected from the group consisting of ethers, tertiary amines, pyridine and pyrolidene compounds.