(CH3)3SiCl/TiCl4 INITIATING SYSTEM FOR CATIONIC POLYMERIZATION OF 1,3-PENTADIENE

 Cationic polymerizations of 1,3-pentadiene (PD) initiated by trimethylsilyl chloride (TMSCl) incombination with TiCl₄ were carried out in n-hexane at 30℃. The yield of polymer was greatly increased bythe addition of TMSCl, indicating that the TMSCl/TiCl₄ combination is an efficient initiating system for PDcationic polymerization. However, the introduction of TMSCl gave rise to a drop in the molecular weight ofthe polymer. Kinetic results demonstrated that the polymerization initiated by TMSCl/TiCl₄ is 4.5 times faster than that induced by TiCl₄ alone.Various ethers were used to mediate the TMSCl/TiCl₄ initiating system.Adding diphenyl ether could increase both the yield and molecular weight of the polymer.Structural evidence illustrates that the polymerization is indeed initiated by TiCl₄ in combination with HCl resulting from bydrolysis by adventitious water.