Studies on Dilithium Initiators. 3. Effect of Additives and Seeding

Lo, Grace Y. S.; Otterbacher, E. W.; Gatzke, A. L.; Tung, L. H.

doi:10.1021/ma00086a038

Cited by 40 publications

(28 citation statements)

References 3 publications

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“…In this way, high 1,4 diene microstructure is attained and the mechanical properties of the materials are similar to those of triblock copolymers obtained with the coupling method [14,16,17]. In this way, high 1,4 diene microstructure is attained and the mechanical properties of the materials are similar to those of triblock copolymers obtained with the coupling method [14,16,17].…”

Section: Coupling Of Living Ab Chainsmentioning

confidence: 55%

Nanostructure Formation in Block Copolymers

Sadeghi

Sayaf

2014

Nanostructured Polymer Blends

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Section: Coupling Of Living Ab Chainsmentioning

confidence: 55%

Nanostructure Formation in Block Copolymers

Sadeghi

Sayaf

2014

Nanostructured Polymer Blends

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“…Seeding techniques with small quantities of isoprene facilitated the carbanion crossover mechanism from the dilithium initiator and promoted homogeneity for the reaction mixture. [ Sequential addition with the remaining isoprene enabled polyisoprenes with increasing molecular weights, targeting M n values of 70 000 g mol −1 (PDI = 1.06) and 150 000 g mol −1 (PDI = 1.08). Copolymerization with styrene also afforded poly(S‐ b ‐I‐ b ‐S) triblock copolymers with controlled molecular weights and narrow polydispersities ( M n = 100 000 g mol −1 , PDI = 1.08 and M n = 120 000 g mol −1 , PDI = 1.09).…”

Section: Resultsmentioning

confidence: 99%

Hydrocarbon‐Soluble Piperazine‐Containing Dilithium Anionic Initiator for High Cis‐1,4 Isoprene Polymerization

Schultz

Bobade

Scott

et al. 2017

Macro Chemistry & Physics

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The synthesis of 1,4‐bis[4‐(1‐phenylethenyl)benzyl] piperazine and subsequent reaction with sec‐butyllithium enables a novel piperazine‐containing difunctional organolithium initiator for the living anionic polymerization of isoprene. Piperazine provides a polar unit within the difunctional initiator, promoting ion dissociation and miscibility with hydrocarbon solvents, and enabling the formation of well‐defined polyisoprene homopolymers with predictable molecular weights and controlled microstructure. In situ Fourier transform infrared spectroscopy monitors the dilithium initiator formation and the anionic polymerization of isoprene, revealing kinetic insight into this synthetic method. Furthermore, sequential monomer addition with styrene affords poly(styrene‐block‐isoprene‐block‐styrene) triblock copolymers with controlled molecular weights and narrow polydispersities. This novel initiator facilitates the synthesis of thermoplastic elastomers with desired cis‐1,4 microstructure in polydienes.

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“…They assumed that the cyclic associates are considerably less reactive than the intermolecular acyclic ones. The authors of the subsequent works [2][3][4][5], in which this phenomenon was investigated in more detail, accepted this explanation too. Madani and colleagues [6] attempted to calculate the fraction of the cyclic associates depending on the length of the "living" bifunctional macromolecules and described the obtained results based on these calculations.…”

Section: Introductionmentioning

confidence: 94%

“…Authors of the works mentioned above [1][2][3][4][5][6] is easy to show that the concentration of the "living" active sites in such gel is huge at the initial stage of polymerization, i.e. for the very short chains.…”

Section: The¯rst Model Of Polymerization In the Two-phase Reaction MImentioning

confidence: 99%

“…Really, addition of electronodonors or monofunctional impurities leads to the reduction or to full disappearance of MWD bimodality of resulting polymers [1], [2], [4]. The additives decrease the cross-linking degree of the gel-phase and thus increase the degree of its swelling and the part of the sol-fraction.…”

Section: The¯rst Model Of Polymerization In the Two-phase Reaction MImentioning

confidence: 99%

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Bimodality of molecular mass distribution of polydienes obtained under the action of dilithium initiators in hydrocarbon media: the reasons, mathematical simulations, and their experimental testing

Estrin

2004

Open Chemistry

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Bimodal molecular mass distribution (MWD) of polymers, obtained upon polymerization of hydrocarbon monomers in the nonpolar media under the action of dilithium initiators, is the consequence of separation of the reaction mixture into two phases. Bifunctional /living/ oligomers produce the insoluble sediment due to tetrameric association of the lithium active sites (the swollen gel-fraction). Part of the active site remains in the solution (the solfraction). Di¬erence in the concentrations of the active sites into the phases leads to di¬erence between the propagation rates of the /living/ chains and, as a result, to Bimodal MWD. The mathematical model of polymerization in the two-phase system is proposed. Satisfactory agreement between the calculations and the experiments is shown for butadiene polymerization in heptane under the action of 1,4-dilithiumpentane. Regulation of MWD up to the complete elimination of bimodality is possible via the programmed dosage of monomer and solvent into the reactor.

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Studies on Dilithium Initiators. 3. Effect of Additives and Seeding

Cited by 40 publications

References 3 publications

Nanostructure Formation in Block Copolymers

Nanostructure Formation in Block Copolymers

Hydrocarbon‐Soluble Piperazine‐Containing Dilithium Anionic Initiator for High Cis‐1,4 Isoprene Polymerization

Bimodality of molecular mass distribution of polydienes obtained under the action of dilithium initiators in hydrocarbon media: the reasons, mathematical simulations, and their experimental testing

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