Copolymerization of styrene with butadiene using methyl tert‐butyl ether as active center modifier

The copolymerization reaction of styrene with butadiene was performed using n-butyllithium (BuLi) as initiator and methyl tert-butyl ether (MTBE) as active center modifier. The randomness of the copolymers increases with decreasing polymerization temperature and increasing [MTBE]/[BuLi] molar ratio. The solvent and the modifier/initiator ratio strongly influence the copolymerization rate. In comparison with other modifiers, MTBE exhibits a moderate action on rate and selectivity of styrene-butadiene copolymerization. The reaction rate increases as the [MTBE]/[BuLi] molar ratio increases from 7 to 40. At higher [MTBE]/[BuLi] molar ratios, the copolymerization rate decreases. First partial reaction orders with respect to styrene and butadiene were calculated. No transfer reactions were detected in cyclohexane, but these are evident in toluene. The microstructure of the butadiene units incorporated into the copolymer chain is little influenced by the polymerization temperature. Higher [MTBE]/[BuLi] molar ratios will lead to an increase in the number of butadiene units incorporated as vinyl units.