Reaction kinetics in anionic copolymerization: A revisit on Mayo-Lewis equation

Wu, Zhichao; Yu, Lei; Wei, Wei; Chen, Fang-shu; Gui-xue, Qiu; Xiong, Huiming

doi:10.1007/s10118-016-1758-8

Cited by 9 publications

(5 citation statements)

References 31 publications

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“…The deviation from the nonintegrated models is not due to the steady-state assumption employed in the derivation of eq . The steady-state approximation refers to a steady-state concentration of living chain ends, which is a valid assumption in many living ionic and catalytic systems. , Moreover, the steady-state assumption is not a required condition for the derivation of the copolymer equation (eq ). , The steady-state assumption does not introduce any significant systematic error unless the concentration of active chain ends changes substantially during the course of the copolymerization.…”

Section: Results and Discussionmentioning

confidence: 99%

Recommendation for Accurate Experimental Determination of Reactivity Ratios in Chain Copolymerization

2019

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A set of copolymerization data at prescribed reactivity ratios was numerically generated and then fit using common methods of data analysis including the copolymer equation, Fineman–Ross, Kelen–Tüdös, and integrated methods of data analysis, such as those reported by Beckingham, Sanoja, and Lynd, and Meyer and Lowry. Significantly, the nonintegrated approaches based on the copolymer equation returned systemically inaccurate reactivity ratios, whereas the integrated methods produced consistently accurate reactivity ratios across 560 calculated data sets. Hence, to determine reactivity ratios with the greatest accuracy and efficiency, we recommend that copolymerization data be fit simultaneously to the models reported by Beckingham–Sanoja–Lynd (BSL) and Meyer–Lowry (ML). If the reactivity ratios are consistent, then a nonterminal model of copolymerization adequately describes the copolymerization with a single reactivity ratio parameter. If there is a difference in the reactivity ratios between BSL and ML, then the ML-derived values take precedence and a terminal model of copolymerization describes the kinetics of the system with two independent reactivity ratios. This prescription will ensure that the model with the least complexity will be used to interpret data, and that the reactivity ratios reported are most accurate and descriptive of the underlying copolymerization mechanism. Future use of the copolymer equation, Fineman–Ross, and Kelen–Tüdös to interpret copolymerization data is strongly discouraged due to unquantifiable inaccuracy and needlessly wasted experimental effort.

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Section: Results and Discussionmentioning

confidence: 99%

Recommendation for Accurate Experimental Determination of Reactivity Ratios in Chain Copolymerization

2019

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“…Real-time 1 H NMR kinetics studies were used to determine homopolymerization kinetics of carbanionic polymerization of various monomers. − However, this method has recently become an important tool to monitor the anionic ring opening copolymerization of epoxides. − In 2013 Natalello et al introduced this method to follow the living carbanionic copolymerization of vinyl monomers . The decrease of the integrals of the double-bond signals in standard 1 H NMR spectra can be followed, which directly translates to monomer incorporation in the resulting copolymers.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Substituent Position on the Anionic Copolymerization of Styrene Derivatives: Experimental Results and Density Functional Theory Calculations

et al. 2019

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In a combined synthetic, kinetic and theoretical study, the living anionic copolymerization of styrene and its ring-methylated derivatives ortho-, meta-, and para-methylstyrene (MS) was examined by real-time 1 H NMR spectroscopy in the nonpolar solvents toluene-d 8 and cyclohexane-d 12 as well as by density functional theory calculations. Based on the NMR kinetics data, reactivity ratios for each comonomer pair were determined by the Kelen−Tudos method and numerical integration of the copolymerization equation (Contour software). The reaction pathway was modeled and followed by density functional theory (DFT) calculations to validate and predict the experimentally derived reactivity ratios. Unexpectedly, two of the three styrene derivatives showed completely different reactivities in copolymerization, governed by the position of the methyl group. While para-MS is considerably less reactive than styrene, resulting in gradient copolymers (r S = 2.62; r pMS = 0.37), ortho-MS showed the opposite behavior and is more reactive than styrene (r S = 0.44; r oMS = 2.47), leading to a reversal of the copolymers' gradient. The substitution in the meta-position had nearly no influence on monomer reactivity, and copolymers with close to random comonomer distribution were formed (r S = 0.81; r mMS = 1.21). In all cases, the theoretical calculations showed good to excellent agreement with the experimental data. Monomer reactivities correlate with the chemical shifts of the β-carbon signals in 13 C NMR spectra that are predictive for the gradient structure. The results demonstrate the possibility of tailoring and validating the polymer structures of functional polystyrene copolymers by the choice of the substitution pattern of styrene derivatives, using both experimental and theoretical approaches.

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“…Our group previously reported in situ 1 H NMR kinetic studies of anionic ring opening polymerization (AROP) of epoxides in vacuum sealed NMR tubes, with the main advantage of the technique being noninvasive . Since then, this technique has been employed to monitor the monomer conversion of a variety of copolymerizations, − including the highly sensitive carbanionic living copolymerization. , …”

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confidence: 99%

Conventional Oxyanionic versus Monomer-Activated Anionic Copolymerization of Ethylene Oxide with Glycidyl Ethers: Striking Differences in Reactivity Ratios

2016

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Detailed understanding of the monomer distribution in copolymers is essential to tailor their properties. For the first time, we have been able to utilize in situ 1H NMR spectroscopy to monitor the monomer-activated anionic ring opening copolymerization (AROP) of ethylene oxide (EO) with a glycidyl ether comonomer, namely, ethoxy ethyl glycidyl ether (EEGE). We determine reactivity ratios and draw a direct comparison to conventional oxyanionic ROP. Surprisingly, the respective monomer reactivities differ strongly between the different types of AROP. Under conventional oxyanionic conditions similar monomer reactivities of EO and EEGE are observed, leading to random structures (r EO = 1.05 ± 0.02, r EEGE = 0.94 ± 0.02). Addition of a cation complexing agent (18-crown-6) showed no influence on the relative reactivity of EO and EEGE (r EO = r EEGE = 1.00 ± 0.02). In striking contrast, monomer-activated AROP produces very different monomer reactivities, affording strongly tapered copolymer structures (r EO = 8.00 ± 0.16, r EEGE = 0.125 ± 0.003). These results highlight the importance of understanding reactivity ratios of comonomer pairs under certain polymerization conditions, at the same time demonstrating the ability to generate both random and strongly tapered P(EO-co-EEGE) polyethers by simple one-pot statistical anionic copolymerization. These observations may be generally valid for the copolymerization of EO and glycidyl ethers.

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Reaction kinetics in anionic copolymerization: A revisit on Mayo-Lewis equation

Cited by 9 publications

References 31 publications

Recommendation for Accurate Experimental Determination of Reactivity Ratios in Chain Copolymerization

Recommendation for Accurate Experimental Determination of Reactivity Ratios in Chain Copolymerization

Effect of the Substituent Position on the Anionic Copolymerization of Styrene Derivatives: Experimental Results and Density Functional Theory Calculations

Conventional Oxyanionic versus Monomer-Activated Anionic Copolymerization of Ethylene Oxide with Glycidyl Ethers: Striking Differences in Reactivity Ratios

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