Novel Ether Modifiers for Anionic Polymerization of Isoprene

Because of demands on tire skid resistance, polyisoprenes with high 3,4-content are of particular interest to the tire industry due to their inherently better grip properties. Polar bidentate modifiers such as TMEDA and DIGLYME are widely used in organo-lithium catalyzed isoprene polymerization to increase 3,4-content. However, neither modifier is very effective for making high Tg polyisoprenes due to the fact that a retarded polymerization rate was found for the former while a large excess of modifier was needed for the latter. The new modifiers based on the alkyl ethers of tetrahydrofurfuryl alcohol with alkyl groups from one to six carbon atoms were found to be very effective for producing polyisoprenes with high 3,4-contents. Kinetic studies on both TMEDA and the new ether modified isoprene polymerizations were conducted. The results and the plausible explanation of the rate difference for both systems are discussed.