Synthesis of chain-end multi-functionalized polyisoprene with a definite number of amino groups via living anionic copolymerization

•Chain-end amine multi-functionalized polydienes could be synthesized via living anionic polymerization.•The amine functionality could be well controlled by using our synthetic and calculation methodology.•Polar additives do not affect the reactivity of DPE-NMe2 in the copolymerization with styrene.

The synthesis of various chain-end multi-functionalized polyisoprene with precisely controlled number of dimethylamino groups has been attempted via living anionic copolymerization. It is based on addition reaction of amino aromatic substituted 1,1-diphenylethylene derivatives and styrene(St) or 2,3-dimethyl-1,3-butadiene(DMBt) to polyisoprenyl lithium using sec-butyllithium as an initiator in benzene at room temperature. Compared to 1,1-bis(4-dimethylaminophenyl)-ethylene(BDMA-DPE), more amine groups can be introduced into polymer chain end when 1-(4-dimethylaminophenyl)-1-phenylethylene (DMA-DPE) units were employed in this system. In addition, amino functionality could be introduced with more tailored fission without any additives compared to that with Tetramethylethylenediamine (TMEDA) or Sodium dodecylbenzene sulfonate (SDBS) as the additive. Furthermore, with DMA-DPE, the amine functionality was readily controlled by adjusting monomer feed ratio according to copolymerization composition equation in our new methodology. At the chain end of resulting multi-functionalized polyisoprene without any additives, the amine functionalities increased from 0.88 to 4.11 with the increasing of monomer feed ratios of [St]/[DMA-DPE]/[Li] from 10:5:1 to 10:40:1, which were constant with the calculated values based on the monomer reactivity ratio. On the other hand, as high as 3.76 amino units could be introduced into polyisoprene chain-end by anionic copolymerization of BDMA-DPE with DMBt at the ratio of [St]/[DMA-DPE]/[Li] = 10:10:1. This system could provide versatile method to introduce well-defined amino groups in to the polymer chain-end conveniently. Not only one amino, but also more than 3 amino groups could be introduced as we expected by USING this synthetic and calculation methodology.

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