Gel-free process for making functionalized anionically polymerized polymers

Abstract

This invention relates to a gel-free process for making functionalized polymers. When multi-alkali metal initiators are used to make these polymers anionically, the process comprises anionically polymerizing at least one monomer with a multi-alkali metal initiator in a hydrocarbon solvent, capping the polymer by adding to the polymer a capping agent that reacts with the ends of the polymer chains such that strongly associating chain ends are formed wherein a strongly associating gel is formed, and, finally, adding a trialkyl aluminum compound to the gel. The important characteristic of the capping agent herein is that it will cap the living polymer and will add a functional group to the polymer chain end which will be strongly associating in the hydrocarbon solvent. In a second embodiment, the present invention relates to a process for making such polymers which comprises anionically polymerizing them as described and adding to the polymer a trialkyl aluminum compound before the alkali metal reacts with the capping agent-functionalized chain ends. Finally, the polymer is capped by adding the above-described capping agent. In the first embodiment, a gel is formed and then removed. In the second embodiment, the gel never is formed because of the presence of the trialkyl aluminum compound.