Structure of initial, ultimate and inner chain units of polybutadiene obtained with a rare-earth catalyst as revealed by 13C nuclear magnetic resonance spectroscopy

Skuratov, K.D.; Lobach, M. I.; Shibaeva, A.N.; Churlyaeva, L. A.; Erokhina, T.V.; Osetrova, L. V.; Kormer, V. A.

doi:10.1016/0032-3861(92)90802-4

Cited by 16 publications

(9 citation statements)

References 9 publications

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“…(Its molecular mass dis tribution is abnormally wide for anionic polymeriza tion, and the values of I aliph /I olef are high.) Evidently, the effect of molecular parameters is difficult to con sider in practice, especially because the manifestation of ring structures [16,31,70], branchings [54,72], and terminal groups [64,65] in the NMR spectra of polyb utadienes was studied only in the case of model com pounds.…”

Section: Confirms This Conclusionmentioning

confidence: 99%

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Makhiyanov

2012

Polym. Sci. Ser. A

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In the polymerization of 1,3 butadiene, chain growth occurs via addition of the monomer at 1,2 or 1,4 positions; in the latter case, cis 1,4 and trans 1,4 configurations can form.It is well known [1,2] that the configurational-iso metric composition (c, t, v) along with other micro structure parameters (monomer unit distributions in a chain, average length of monomer block sequences, specific content of possible combinations of units, etc.) exert the decisive effect on the properties of PB. The relationship between the parameters (c, t, v) and properties of PB is still at the focus of researchers' attention [3][4][5][6][7]. In this case, the question arises as to whether the determination of the above parameters is correct [6].The structure of PB is investigated with the use of such nondestructive methods as vibrational spectros copy (IR and Raman) [8][9][10][11][12][13][14][15] and high resolution NMR . In research and industrial laborato ries, IR spectroscopy is the most popular method owing to its accessibility and simplicity. However, for quantitative measurements, this method requires cali bration [13] and is inferior to NMR spectroscopy in informative value. Over the past half century, the structure of PB has been intensively studied with the use of NMR spectroscopy: high resolution 1 H [16-36] and 13 C [33, 37-73] NMR spectroscopy of liquid (dissolved) samples, solid state 13 C NMR spectros copy [74][75][76], and two dimensional spectroscopy [73,[77][78][79]. Despite the considerable progress of mag netic resonance techniques, solid state and multidi mensional variants are still inferior to "classical" (i.e., liquid one dimensional) NMR for solving quantita tive problems. Therefore, our study concerns only the potential of the latter method for estimating the values of c, t, and v for polybutadiene.The use of NMR spectroscopy for the quantitative analysis of the structure of PB was discussed in [11,17,30,51,59,60]. However, this problem is still topical. First, the requirements imposed on the informative level and accuracy of the NMR method [80-82], including those for the study of polymers [83], are increasing steadily. Second, a widespread opinion about the completeness of assignment and easy analy sis of the spectra of PB as the simplest diene polymer is contrary to reality [6, 71-73, 79, 84].The goal of this study is to solve a complex of meth odological problems arising during determination of the isomeric composition of PB with the use of NMR spectroscopy. EXPERIMENTALCommercial PBs (DOW SE BR 1202D, BUNA CB 530T, DOW SE PB 5800, SKDN and SKD L rubbers manufactured by OAO Nizhnekam skneftekhim, and SKB and SKD 2 manufactured by the Kazan and Efremov synthetic rubber plants, respectively) and laboratory samples PB 11, PB 15, PB 35, PB 38, PB 55, and PB 67 were used in this study. Laboratory samples were synthesized with the use of a lithium containing initiation system, as described in [84]. The PB samples were dissolved in chloroform d and benzene d 6 (the solution concen tration was 1 wt %) when th...

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Section: Confirms This Conclusionmentioning

confidence: 99%

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Makhiyanov

2012

Polym. Sci. Ser. A

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“…Ziegler‐Natta catalyst systems based on neodymium constitute a relevant class of catalysts that have been used industrially in commercial industrial scale polymerizations of conjugated dienes, due to their excellent stereoselectivity and high activity. [ 1–3 ] However, these catalysts still provide poor controllability over average molecular weights and molecular weight distributions (MWD) of the obtained polymer material because of the presence of multiple active species and to the heterogeneity of the catalyst system. [ 4 ]…”

Section: Introductionmentioning

confidence: 99%

“…Ziegler-Natta catalyst systems based on neodymium constitute a relevant class of catalysts that have been used industrially in commercial industrial scale polymerizations of conjugated dienes, due to their excellent stereoselectivity and high activity. [1][2][3] However, these catalysts still provide poor controllability over DOI: 10.1002/mren.202100005 average molecular weights and molecular weight distributions (MWD) of the obtained polymer material because of the presence of multiple active species and to the heterogeneity of the catalyst system. [4] The living coordinative polymerization constitutes a reliable alternative to perform controlled polymerizations of conjugated dienes; [5,6] nevertheless, this kind of polymerization produces only one polymer chain per active metal center in ideal reaction conditions, which can be very expensive because of the relatively high catalyst concentrations required by the technique and the high costs of the catalyst.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Isoprene Solution Coordinative Chain Transfer Polymerization

Sá

Cordova

Gómez

et al. 2021

Macro Reaction Engineering

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The present manuscript investigates the solution coordinative chain transfer polymerization (CCTP) of isoprene initiated by the ternary Ziegler‐Natta catalyst system composed by neodymium versatate (NdV3), diisobutylaluminum (DIBAH), and dimethyldichlorosilane. A kinetic mechanism is proposed and the kinetic parameters are estimated to allow the appropriate description of dynamic trajectories of average molecular weights and isoprene conversions obtained in solution CCTP polymerizations for the first time. A data reconciliation strategy is applied to evaluate the amount of DIBAH used as a chain transfer agent, as this very active compound can be consumed by undesired side reactions. Additionally, the impacts of key operation variables on the control of the average molecular weights and monomer conversion are evaluated to elucidate the living nature of the polymerization. As observed experimentally, the temperature effect on the course of the polymerization is not so pronounced as the effect of NdV3, isoprene, and DIBAH initial concentrations. The kinetic mechanism is described better and kinetic constants are estimated more precisely when the dynamic trajectories of average molecular weights are fitted during the whole batch. In this case, the proposed model is able to predict well the experimental trajectories of average molecular weights of the produced polymer and monomer conversion.

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“…Among different methods used for the investigation of structure of the polybutadiene chain, NMR spectroscopy is the most efficient. The structure and content of structural units, distribution of sequences of repeated units along the polymer chain, the number and type of branchings in polybutadiene was established using NMR spectroscopy …”

Section: Introductionmentioning

confidence: 99%

Structural characterization of polybutadiene synthesized via cationic mechanism

Розенцвет¹,

Stotskaya²,

Иванова

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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The microstructure of polybutadiene synthesized via cationic polymerization using TiCl4‐based initiating systems has been investigated using 1D (1Н, 2Н, and 13С) and 2D (HSQC and HMBC) NMR spectroscopy. It was found that trans‐1,4‐unit is predominant structure of unsaturated part of polymer chain. Besides, the small amount of 1,2‐structures was also detected, while cis‐1,4‐units were totally absent. The signals of carbon atoms of three types of head groups (trans‐1,4‐, 1,2‐, and tert‐butyl) and two types of end groups (trans‐1,4‐Cl and 1,2‐Cl) were identified for the first time in macromolecules of cationic polybutadiene. It was showed that tert‐butyl head groups were formed due to the presence in monomer of admixtures of isobutylene. The new methodology for calculation of the content of different structural units in polybutadiene chain as well as the head and end groups was proposed. It was established that main part of 1,2‐units distributed randomly along the polybutadiene chain as separate units between trans‐1,4‐structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 387–398

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Structure of initial, ultimate and inner chain units of polybutadiene obtained with a rare-earth catalyst as revealed by 13C nuclear magnetic resonance spectroscopy

Cited by 16 publications

References 9 publications

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Modeling of Isoprene Solution Coordinative Chain Transfer Polymerization

Structural characterization of polybutadiene synthesized via cationic mechanism

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