Anionic Grafting of Polystyrene from Carbon Blacks Catalyzed by Oli Groups on the Carbon Black Surface in the Presence of Crown Ether

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Abstract
Carbon black carrying OLi groups, which was prepared by the reaction of the oxygen-containing groups on the surface with n-butyllithium (BuLi), was unable to initiate anionic polymerization of styrene. However, anionic polymerization of styrene is initiated by OLi group on carbon black in the presence of a crown ether, such as 12-crown-4 and 18-crown-6. Then polystyrene was effectively grafted from carbon black owing to the propagation of polystyrene from the OLi groups. The grafting ratio increased with increasing amount of BuLi used for pretreatment of the carbon black and was a maximal (170%) in the presence of carbon black pretreated with BuLi in a quantity equivalent to its oxygen-containing groups. When carbon black was pretreated with excess BuLi, i.e., in the presence of free BuLi, the grafting ratio decreased to less than 20% because the formation of ungrafted polystyrene by free BuLi occurs preferentially to the propagation from the OLi groups on carbon black. Furthermore, it was found that the anionic polymerization of a-methylstyrene was initiated in the presence of crown ether by OLi groups, but OLi groups failed to initiate the polymerization of isoprene, even in the presence of crown ether.
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