Effect of lithium tert-alkoxides on anionic polymerization of butadiene initiated with a bifunctional initiator

Polymerization of buta-1,3-diene initiated by bifunctional dilithium initia tor in tert-butyl methyl ether, hexane and hexane-toluene mixtures was stud ied in the presence of Li tert-butoxide, 2-methylpentan-2-olate, 3-methylpe ntan-3-olate or 2,3-dimethylbutan-2-olate. The alkoxides lower the overall polymerization rate and affect, to a certain extent, microstructure of form ed polymers. When applied in a concentration equal to that of the initiatin g centres, they lower the content of vinyl structures in polybutadiene by 1 0-12%. Increasing concentration of the alkoxide has no perceptible effect a nd, if used in 12-fold excess over the initiator, the content of 1,2-struct ures even increases. Polymers prepared in the presence of an alkoxide mostl y have unimodal and narrow MWDs.