Living free radical polymerization (RAFT) of dodecyl acrylate: Chain length dependent termination, mid-chain radicals and monomer reaction order

Theis, Alexander; Feldermann, Achim; Charton, Nathalie; Davis, Thomas P.; Stenzel, Martina H.; Barner‐Kowollik, Christopher

doi:10.1016/j.polymer.2005.06.004

Cited by 69 publications

(99 citation statements)

References 47 publications

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“…RAFT polymerization and kinetic simulation with Predici have been applied to determine chain-length dependent termination rate constants in radical polymerizations [70,[99][100][101]121,142,143] of various monomers including MA (with 40 [99,143] or 66b [143] ), BA (with 40 [100] or 66a [116] ), DA (with 40 or 66b [101] ), MMA (with 9 [70] ), and VAc (with 70b [121] ). Most experiments [70,99,100,121] involve collecting 38* (DBI) [64] S [76] 39* MA [96] (NVP) [97] S [96] (S) [98] 40* MA [99] BA [100] DA [101] S S O OH S S R S S 41* NIPAM [102] 42* [72] MA [87] XA [72] 43a* R = CH 3 S [74] 43b R = C 2 H 5 MA [87] …”

Section: Polymerization Kineticsmentioning

confidence: 99%

Living Radical Polymerization by the RAFT Process—A First Update

Moad¹,

Rizzardo²,

Thang³

2006

Aust. J. Chem.

859

787

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This paper provides a first update to the review of living radical polymerization achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of Reversible Addition-Fragmentation chain Transfer (RAFT) published in June 2005. The time since that publication has witnessed an increased rate of publication on the topic with the appearance of well over 200 papers covering various aspects of RAFT polymerization ranging over reagent synthesis and properties, kinetics, and mechanism of polymerization, novel polymer syntheses, and diverse applications.

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Section: Polymerization Kineticsmentioning

confidence: 99%

Living Radical Polymerization by the RAFT Process—A First Update

Moad¹,

Rizzardo²,

Thang³

2006

Aust. J. Chem.

859

787

View full text Add to dashboard Cite

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“…Similar chain length dependencies have been reported for other acrylates, including methyl acrylate 85 and dodecyl acrylate. 66,86,87 Prior to this study, the conversion dependence of the average termination rate coefficient in butyl acrylate polymerization, hk t i, was mapped to conversion of up to 60%, showing a decrease after 10% conversion. 23,60,88 In the low conversion regime (where hk t i is largely constant), the variation of the average termination rate coefficient with temperature can be approximated (at 1000 bar pressure) by the following Arrhenius expres- To the best of our knowledge, there have been no determinations of intramolecular chain transfer rate coefficients in acrylate polymerizations.…”

Section: Chain-end Termination Rate Coefficient (Secondary Radicals)mentioning

confidence: 99%

The role of mid‐chain radicals in acrylate free radical polymerization: Branching and scission

Junkers

Barner‐Kowollik

2008

J. Polym. Sci. A Polym. Chem.

213

326

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The past 5 years have seen a significant increase in the understanding of the fate of so‐called mid‐chain radicals (MCR), which are formed during the free radical polymerization of monomers that form highly reactive propagating radicals and contain an easily abstractable hydrogen atom. Among these monomers, acrylates are, beside ethylene, among the most prominent. Typically, a secondary propagating acrylate‐type macroradical (SPR) can easily transfer its radical functionality via a six‐membered transition state to a position within the polymer chain (in a so‐called backbiting reaction), creating a tertiary MCR. Alternatively, the radical function can be transferred intramolecularly to any position within the chain (also forming an MCR) or intermolecularly to another polymer strand. This article aims at providing a comprehensive overview of the up‐to‐date knowledge about the rates at which MCRs are formed, their secondary reactions as well as the consequences of their occurrence under variable reaction conditions. We explore the latest aspects of their detection (via electron spin resonance spectroscopy) as well as the characterization of the polymer structures to which they lead (via high resolution mass spectrometry). The presence of MCRs leads to the formation of branched polymers and the partial formation of polymer networks. They also limit the measurement of kinetic parameters (such as the SPR propagation rate coefficient) with conventional methods. However, their occurrence can also be used as a synthetic handle, for example, the high‐temperature preparation of macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7585–7605, 2008

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“…[55][56][57] To account for the influence of these on the determination of k t (t), Barner-Kowollik and coworkers 42 proposed replacing k p with an expression based on the first order (i.e., low temperature) propagation rate coefficient, k p0 , and the monomer reaction order, x.…”

Section: Accounting For Mid-chain Radical Formationmentioning

confidence: 99%

Bimolecular radical termination: New perspectives and insights

Johnston‐Hall

Monteiro

2008

J. Polym. Sci. A Polym. Chem.

133

216

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ABSTRACT:The reversible addition-fragmentation chain transfer-chain length dependent termination (RAFT-CLD-T) method has allowed us to answer a number of fundamental questions regarding the mechanism of diffusion-controlled bimolecular termination in free-radical polymerization (FRP). We carried out RAFTmediated polymerizations of methyl acrylate (MA) in the presence of a star matrix to develop an understanding of the effect of polymer matrix architecture on the termination of linear polyMA radicals and compared this to polystyrene, polymethyl methacrylate, and polyvinyl acetate systems. It was found that the matrix architecture had little or no influence on termination in the dilute regime.However, due to the smaller hydrodynamic volumes of the stars in solution compared to linear polymer of the same molecular weight, the gel onset point occurred at greater conversions, and supported the postulate that chain overlap (or c*) is the main cause for the observed autoacceleration observed in FRP. Other theories based on \short-long" termination or free-volume should be disregarded. Additionally, since our systems are well below the entanglement molecular weight, entanglements should also be disregarded as the cause of the gel onset. The semidilute regime occurs over a small conversion range and is difficult to quantify. However, we obtain accurate dependencies for termination in the concentrated regime, and observed that the star polymers (through the tethering of the arms) provided constriction points in the matrix that significantly slow the diffusion of linear polymeric radicals. Although, this could at first sight be postulated to be due to reptation, the dependencies showed that reptation could be considered only at very high conversions (close to the glass transition regime). In general, we find from our data that the polymer matrix is much more mobile than what is expected if reptation were to dominate.

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Living free radical polymerization (RAFT) of dodecyl acrylate: Chain length dependent termination, mid-chain radicals and monomer reaction order

Cited by 69 publications

References 47 publications

Living Radical Polymerization by the RAFT Process—A First Update

Living Radical Polymerization by the RAFT Process—A First Update

The role of mid‐chain radicals in acrylate free radical polymerization: Branching and scission

Bimolecular radical termination: New perspectives and insights

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