Living Anionic Polymerization of 1,4-Diisopropenylbenzene.
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| Title: | Living Anionic Polymerization of 1,4-Diisopropenylbenzene. |
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| Authors: | Raita Goseki1, Suguru Onuki1, Shunsuke Tanaka1, Takashi Ishizone1, Akira Hirao1 |
| Source: | Macromolecules. May2015, Vol. 48 Issue 10, p3230-3238. 9p. |
| Subjects: | Alpha-methylstyrol, Addition polymerization, Uniform polymers, Nucleophilic reactions, Isopropenyl compounds |
| Abstract: | Theanionic polymerization of diisopropenylbenzene (DIPB) derivativeswas conducted in THF at −78 °C with a specially designedinitiator system prepared from oligo(α-methylstyryl)lithiumand an excess potassium tert-butoxide (KOBut) (2.7–5.0 equiv to the Li salt). Among the ortho-, meta-, and para-isomers of DIPBderivatives, it was found that the para-isomer (p-DIPB) successfully underwent the living polymerizationin a selective manner through one of the two isopropenyl groups underthe above stated conditions. With this living polymerization system,soluble polymers with controllable Mnvaluesranging from 7620 to 31 500 g/mol and near monodisperse distributions(Mw/Mn≤1.03) were obtained for the first time. The obtained living polymerswere stable at −78 °C even after 168 h and at −40°C after 6 h, in which the intermolecular addition reaction ofthe chain-end anion to the pendant isopropenyl group could be completelysuppressed. In contrast, the living polymerization of either the ortho- or meta-isomer was not successfulunder the same conditions. The block copolymerization of p-DIPB with either styrene (S), 2-vinylpyridine (2VP), or tert-butyl methacrylate (tBMA) by the sequentialaddition of such monomers was conducted. Four new PS-block-P(p-DIPB), P2VP-block-P(p-DIPB), P(p-DIPB)-block-P2VP, and P(p-DIPB)-block-PtBMA containing reactive P(p-DIPB) segmentswere synthesized. On the basis of the block copolymerization results,it is understood that p-DIPB is comparable to 2VPand located between S and tBMA in monomer reactivity. Thereactivity increases as follows: S < 2VP ∼ p-DIPB < tBMA, while the nucleophilicity of the livingchain-end anion decreases in the following order: PS–> P2VP–∼ P(p-DIPB) –> P(tBMA) –. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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