Anionic polymerization of isoprene by oligoisoprenyllithium/tertiary polyamine complexes in cyclohexane. 2. Proton magnetic resonance and ultraviolet spectroscopy of propagating living species

Collet-Marti, Viviane; Dumas, Sylviane; Sledz, J.; Schué, François

doi:10.1021/ma00230a009

Cited by 11 publications

(3 citation statements)

References 6 publications

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“…The final buildup of the shoulder ~325 nm can be similarly attributed to the monosolvated monomeric species as before. 6 The weakness of this signal even at R = 3.5 as compared with the TMEDA case where a strong isolated band is formed already at R = 2 is in agreement with the NMR evidence that monomeric solvated species are much more readily formed with TMEDA than DIPIP. The percentage of monomeric species is, however, still increasing at R ~3.5 so that at very high DIPIP ratios (-15) an isolated absorption band (Xmax 327 nm) is ob-Lithium Alkyl Initiated Polymerization of Isoprene 1327 served, indicating more complete dissociation.…”

Section: Discussionsupporting

confidence: 83%

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Polymer structure and complexes in the lithium alkyl initiated polymerization of isoprene in the presence of 1,2-dipiperidinoethane

Bres¹,

Viguier²,

Sledz³

et al. 1986

Macromolecules

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A study of the complexes formed between lithium and 1,2-dipiperidinoethane in oligomeric active chains of polyisoprene is reported. A comparison of NMR and electronic spectra indicates little drift of complex distribution over a wide concentration range. No major differences in behavior were found between the present NMR results and those reported on a simple one-unit growing chain with a fert-butyl end group. The results offer confirmatory evidence for the validity of a mechanism suggested on the basis of NMR studies on the one-unit model. This involved solvated tetrameric, dimeric, and monomeric forms of the organolithium intermediates. The effect of the presence of both 1,4-and 4,1-type chain ends on polymer microstructure is discussed.

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Section: Discussionsupporting

confidence: 83%

“…The preparation of a 1:1 adduct of tert-butyllithium and isoprene has been adequately described earlier. 6 In the present investigation the preparation of an oligomer of DP ~3 was carried out in the same manner by simply increasing the 7 Issued as NRCC No. 25562. 0024-9297/86/2219-1325801.50/0 isoprene-to-tert-butyllithium ratio.…”

Section: Methodsmentioning

confidence: 99%

Polymer structure and complexes in the lithium alkyl initiated polymerization of isoprene in the presence of 1,2-dipiperidinoethane

Bres¹,

Viguier²,

Sledz³

et al. 1986

Macromolecules

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“…Also, three kinetic runs were performed at DIPIP/Li ratios between 3.4 and 5. 6 at the same lithium concentration; the rates were found to be essentially the same. Evidently at these concentrations all chain ends are fully solvated and no longer aqso- Fig.…”

Section: Resultsmentioning

confidence: 72%

The anionic polymerization of butadiene in the presence of dipiperidinoethane

Bywater

MacKerron

Worsfold

et al. 1985

J. Polym. Sci. Polym. Chem. Ed.

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The polymerization of butadiene by lithium‐based initiators in aliphatic hydrocarbon solvents in the presence of dipiperidinoethane gives a highly 1,2 structure. This system was studied to determine the factors that govern the structure. The effect of this complexing agent on the kinetics of propagation, the microstructure of the polymer, and the ultraviolet spectrum of the active chain end was measured. The results suggest that more than one solvated species form, all giving highly 1,2 polymer structures, but that a solvate containing one chain end with one dipiperidinoethane molecule is the principal reacting species which gives close to 100% 1,2 structure. This reacting center has a high proportion of trans‐structure in the allyllic ion, únlike most complexed active chain ends, which are often highly cis. It is this transstructure in the ion that is thought to be responsible for the polymer structure.

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Isoprene Polymers

Senyek

2008

Encyclopedia of Polymer Science and Technology

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Isoprene was first isolated from the pyrolysis products of natural rubber. The first preparation of polyisoprene was reported in 1879. In 1950, the goal of preparing synthetic cis 1,4‐polyisoprene as a counter part to natural rubber was achieved. Attention was then focused on commercial preparation of isoprene for polymerization use. Shortly after the discovery of stereospecific catalysts, the first commercial polyisoprene plant came on stream in 1959–1960 using a lithium catalyst. Isoprene is a reactive diene that undergoes cycloaddition, electrophilic, nucleophilic, free‐radical, and coordinated catalytic addition, and thermal dimerization. Information on the production of isoprene by naphtha cracking as well as the synthetic processes is detailed. Depending on the catalyst and conditions, isoprene may undergo 1,2,3,4, or 1,4 addition leading to several isomeric structures. Coordination catalysts, alkali metal catalysts, and Alfin catalysts are important for polymerization and are discussed. Chemical modification of polymers is a convenient way of altering physical and mechanical properties. Highly unsaturated polymers such as polyisoprene are easily modified because the olefinic bond is readily available. Their high reactivity with a variety of chemical substances offers advantages in chemical modification and vulcanization. However, reaction with oxygen and ozone causes degradation and loss of physical and mechanical properties. Synthetic polyisoprene is processed on conventional rubber machinery. Compounding technology is similar to that used for natural rubber. Typical formulations are given. A brief discussion of isoprene copolymers and 1,4‐ trans ‐polyisoprene is included. Isoprene is classified as a flammable liquid. It is a moderate irritant to the skin, eyes, and mucous membranes. The primary use for cis ‐1,4‐polyisoprene is in tires and tire products. It is also used, eg, in molded and mechanical goods, adhesives, belts, foam rubber, and elastic threads.. Automotive molded products and medical applications are typical. Trans ‐1,4‐Poyisoprene can be extracted, calendered, injection molded, and compression molded. It can be used in blends with other polymers. Its main use is in golf ball covers.

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Anionic polymerization of isoprene by oligoisoprenyllithium/tertiary polyamine complexes in cyclohexane. 2. Proton magnetic resonance and ultraviolet spectroscopy of propagating living species

Cited by 11 publications

References 6 publications

Polymer structure and complexes in the lithium alkyl initiated polymerization of isoprene in the presence of 1,2-dipiperidinoethane

Polymer structure and complexes in the lithium alkyl initiated polymerization of isoprene in the presence of 1,2-dipiperidinoethane

The anionic polymerization of butadiene in the presence of dipiperidinoethane

Isoprene Polymers

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