Anionic Polymerization Of Styrene/Butadiene Catalyzed By KH(NaH)

In the last20years, Deffieux researched that we added metal alkyl to the system which can form a new complex,such complex can decrease the activity of active centre.so,they present the concept of RAP.This discovery provided a theoretical basis for High concentrations of anionic polymerization.This group research the retarded behavior for system of Mg/Li、B(Zn)/Li、Al/Li. On its basis, the use of alkyl metal hydride/Lewis acid instead of butyl lithium initiate the polymerization of styrene.we basis previous studies on RAP reaction.preparing a new inititor system.And studied the reaction behavior for styrene/butadiene.For the KH/1-BU3Al system,its initator activity related with [K]/[A1] ratio. Elevated temperature and the addition of a few equivalents of a polar additive can improve initiator activity.Meanwhile we found that the active of styrene are higher than butadiene basising on copolymerization kinetics. KH/B(Et)3system can’t initiate polymerization of styrene at low temperature. However, addition of a few equivalents of a polar additive,such as dioxane, also allows the polymerization to procced. At high temperature, the activity of the initiator system are also improved. After6h reaction the monomer conservation reaches100%.The polymerization reaction kinetics of styrene at high temperature shows that the reaction rate is low.For the NaH/i-Bu3Al system, this initiator system is highly active in initiation of the polymerization under high temperature, while it is even inactive in a relatively cold environment.6hours are enough to make conversion rate reach80%～90%. The molecule weight is not very impressionable while Mw/Mn becomes less as the ratio goes less. The microcosmic structure is impressionable enough from the influence of the ratio and temperature.