Effects of polar additives on the anionic polymerization of 1,3-butadiene and styrene

The homopolymerization of butadiene and co-polymerization of styrene with butadiene were performed using n-butyllithium as the initiator, cyclohexane as a solvent and some new ethers (sigma-ligands) as active centers modifiers. The modifiers were synthesized using an elegant synthetic route starting from a commercial precursor, and high yields were obtained. Their addition in the homopolymerization of butadiene strongly influences the vinyl content and reduces the polydispersity of the obtained polymer. The modifiers are also able to change the reactivity ratios in the styrene-butadiene copolymerization, leading to an appreciable randomizing effect. The modifiers also show a high activity, since their addition in a very low amount is able to strongly modify the progress in the reaction of anionic polymerization.