Intramolecular Chain Transfer to Polymer in the Emulsion Polymerization of 2-Ethylhexyl Acrylate

Plessis, Christophe; Arzamendi, Gurutze; Alberdi, J. M.; Agnely, Mathias; Leiza, José R.; Asúa, José M.

doi:10.1021/ma0018190

Cited by 91 publications

(90 citation statements)

References 23 publications

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“…Final values are presented in Table 2. The polymerization of acrylic monomers (in the present case, 2-EHA) yields a gel due to the chain transfer to the polymer coupled by termination via combination 55 . The gel fraction in the PU-acrylic hybrid is even higher than in the standard acrylic.…”

Section: Latex Polymerization and Characteristicsmentioning

confidence: 92%

Waterborne Polyurethane−Acrylic Hybrid Nanoparticles by Miniemulsion Polymerization: Applications in Pressure-Sensitive Adhesives

et al. 2011

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Abstract. Waterborne polyurethane-acrylic hybrid nanoparticles for application as pressuresensitive adhesives (PSAs) were prepared by a one-step miniemulsion polymerization. The addition of polyurethane into a standard waterborne acrylic formulation results in a large increase of the cohesive strength and hence a much higher shear holding time (greater than seven weeks at room temperature), which is a highly desirable characteristic for PSAs. However, with the increase in cohesion, there is a decrease in the relative viscous component, and hence there is a decrease in the tack energy. The presence of a small concentration of methyl methacrylate (MMA) in the acrylic copolymer led to phase separation within the particles and created a hemispherical morphology. The tack energy was particularly low in the hybrid containing MMA because of the effects of lower energy dissipation and greater crosslinking. These results highlight the great sensitivity of the * Corresponding author. E-mail: j.keddie@surrey.ac.uk. Tel +44-1483-686803; Fax +44-1483- 686781.Published in Langmuir (2011) 27(7) pp 3878-3888 2 viscoelastic and adhesive properties to the details of the polymer network architecture and hence to the precise composition and synthesis conditions.

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Section: Latex Polymerization and Characteristicsmentioning

confidence: 92%

Waterborne Polyurethane−Acrylic Hybrid Nanoparticles by Miniemulsion Polymerization: Applications in Pressure-Sensitive Adhesives

et al. 2011

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“…One of the most consequential experimental observations associated with the formation of MCRs in acrylate polymerization and their subsequent side reactions is the inability to derive propagation rate coefficient at temperatures exceeding 30 C from so-called PLP-SEC experiments. 20 As it is not the intention of this article to reiterate the details of the PLP-SEC methodology, the reader is referred to the relevant papers outlining its working principle (e.g., see refs.…”

Section: Impact Of Mid-chain Radicals On the Plp-sec Methodsmentioning

confidence: 99%

“…[24][25][26] Although, not unlike the discussion about the monomer reaction order x, other factors such as transfer to monomer were discussed, 24 Asua and coworkers soon made the connection to the transfer to polymer reactions. [27][28][29][30][31][32] No reliable k p data for conditions under which polymerizations usually are applied are available, 33 and only rate coefficients that are extrapolated from the low-temperature polymerization data are in use. However, this extrapolation can only be seen as an approximation for the propagation rate coefficient of the SPR species, and the effective propagation rate is much lower due to the significantly reduced activity of the MCRs.…”

Section: Introductionmentioning

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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“…Plessis et al [6,7] developed a complete kinetic model that accounts for the two radical species (secondary and tertiary radicals) and its different reactivities, and reported that the apparent propagation rate for the homopolymerizations of BA and 2EHA at 75 8C was almost one order of magnitude lower than that estimated by extrapolation of k p values determined from pulsed-laser polymerization/size exclusion chromatography (PLP/SEC) experiments carried out at low temperatures. Azukizawa et al [10] and Yamada et al [11] , by extrapolating data of radical concentration at zero conversion, were able to estimate the propagation rate constants for PhA and CHA monomers and reported that these were one order of magnitude lower than the values estimated for acrylates by extrapolation.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Intramolecular Chain Transfer to Polymer on PLP/SEC Experiments of Alkyl Acrylates

Arzamendi

Plessis

Leiza

et al. 2003

Macro Theory & Simulations

Self Cite

110

125

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Pulsed‐laser polymerization (PLP) has been adopted by IUPAC as the method of choice for the determination of propagation rate constants (kp). However, the method has failed in the polymerization of alkyl acrylates at temperatures above 30 °C. In this work, the PLP experiments were analyzed by simulation using a Monte Carlo algorithm. It was found that the experimental difficulties encountered to accurately determine kp at temperatures above 30 °C were caused by extensive intramolecular chain transfer. This mechanism is not operative at lower temperatures because of its high activation energy.Pulsed‐laser polymerization of BA in bulk at temperatures between −41 and +40 °C: Simulated MWD trace.imagePulsed‐laser polymerization of BA in bulk at temperatures between −41 and +40 °C: Simulated MWD trace.

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Intramolecular Chain Transfer to Polymer in the Emulsion Polymerization of 2-Ethylhexyl Acrylate

Cited by 91 publications

References 23 publications

Waterborne Polyurethane−Acrylic Hybrid Nanoparticles by Miniemulsion Polymerization: Applications in Pressure-Sensitive Adhesives

Waterborne Polyurethane−Acrylic Hybrid Nanoparticles by Miniemulsion Polymerization: Applications in Pressure-Sensitive Adhesives

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

Effect of the Intramolecular Chain Transfer to Polymer on PLP/SEC Experiments of Alkyl Acrylates

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