Chain-Length Dependence of Termination Rate Coefficients in Acrylate and Methacrylate Homopolymerizations Investigated via the SP−PLP Technique

Buback, Michael; Egorov, Mark; Feldermann, Achim

doi:10.1021/ma0350922

Cited by 53 publications

(76 citation statements)

References 34 publications

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“…[131] Using the time-resolved singlepulse pulsed-laser-polymerization technique (SP-PLP), Buback et al [132] were able to measure k t values up to high degrees of monomer conversion. They verified the value of e as being close to 0.16 for methacrylates but only at low degrees of monomer conversion.…”

Section: Chain Length Dependent Terminationmentioning

confidence: 99%

A Review of Modeling of Diffusion Controlled Polymerization Reactions

Achilias¹

2007

Macro Theory & Simulations

234

292

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A plethora of models have been developed quantifying the effect of diffusion‐controlled phenomena on polymerization reactions. The most prominent approaches are reviewed here, including innovative ones that have emerged over the last decade. Free‐radical and step‐growth polymerizations are considered in a way to show that similar models have been used in both mechanisms. In free‐radical polymerization the models proposed are subdivided according to their theoretical background into four categories: (i) based on a Fickian description of reactant diffusion; (ii) free‐volume theory based; (iii) chain‐length dependent; and, (iv) empirical. The reversible addition‐fragmentation technique is discussed, together with two industrially important case‐studies, solid state polycondensation and epoxy‐amine curing.magnified image

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Section: Chain Length Dependent Terminationmentioning

confidence: 99%

A Review of Modeling of Diffusion Controlled Polymerization Reactions

Achilias¹

2007

Macro Theory & Simulations

234

292

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“…Moreover, it needs to be noted that the a value from SP-PLP-ESR is higher than the SP-PLP-NIR value of a ¼ 0.15 AE 0.04. [13] This is probably due to the fact that the NIR technique, which is applied at higher temperatures, primarily catches the chain-length dependence of k t for larger radicals, which is weaker than the one for small radicals (see below).…”

Section: Experimental Partmentioning

confidence: 99%

Free‐Radical Termination Kinetics Studied Using a Novel SP‐PLP‐ESR Technique

Buback

Egorov

Junkers

et al. 2004

Macromol. Rapid Commun.

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144

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Summary: A novel method for measuring termination rate coefficients, kt, in free‐radical polymerization is presented. A single laser pulse is used to instantaneously produce photoinitiator‐derived radicals. During subsequent polymerization, radical concentration is monitored by time‐resolved electron spin resonance (ESR) spectroscopy. The size of the free radicals, which exhibits a narrow distribution increases linearly with time t, which allows the chain‐length dependence of kt to be deduced. The method will be illustrated using dodecyl methacrylate polymerization as an example.

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“…Buback et al recently reported circumstantial evidence for the presence of MCR in acrylate polymerization using the single-pulse PLP method. [34] It was postulated that the MCR content increased with increasing size of the ester alkyl group and with decreasing monomer concentration. Furthermore, rapid termination of the expelled radical by b-fragmentation of MCR might provide a faster pathway than termination reactions involving MCR leading to faster overall termination.…”

Section: Determination Of Apparent K P and K T Valuesmentioning

confidence: 99%

Influence of Mid‐Chain Radicals on Acrylate Free Radical Polymerization: Effect of Ester Alkyl Group

Sato

Emoto

Zetterlund

et al. 2004

Macro Chemistry & Physics

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Summary: The benzene solution polymerizations of tert‐butyl acrylate (tBA) and 2‐ethylhexyl acrylate (EHA) have been investigated with respect to the effects of mid‐chain radicals (MCRs) on the rate of polymerization, the total radical concentration, the apparent rate coefficients for propagation, termination, and β‐fragmentation, the contents of unsaturated end groups and branching, and the molecular weight distribution. The EHA polymerization involves a considerably higher concentration of MCR and is more significantly affected by MCR than the tBA polymerization. The MCR content as estimated by electron paramagnetic resonance (EPR) spectroscopy during photosensitized EHA polymerization was as high as 70% of the total radical concentration at 25 °C. However, no 1H and 13C NMR resonances due to unsaturated ends and branching, respectively, were detected for the poly(EHA) obtained at 25 °C. These findings indicate that a high MCR content does not directly correspond to significant MCR effects on the polymer structure. The rate constants for mutual reaction ($k'_{\rm t}$) and β‐fragmentation (kf) of MCR were estimated for the two assumed cases where MCR was consumed solely by (i) mutual reaction, and (ii) β‐fragmentation, based on the after‐effect of the photosensitized EHA polymerization monitored by EPR spectroscopy at 25 °C; $k'_{\rm t}$ = 3.5 × 103 L · mol · s−1 and kf = 4.2 × 10−2 s−1. These rate coefficients were compared with those for reactions of structurally similar radicals.

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Chain-Length Dependence of Termination Rate Coefficients in Acrylate and Methacrylate Homopolymerizations Investigated via the SP−PLP Technique

Cited by 53 publications

References 34 publications

A Review of Modeling of Diffusion Controlled Polymerization Reactions

A Review of Modeling of Diffusion Controlled Polymerization Reactions

Free‐Radical Termination Kinetics Studied Using a Novel SP‐PLP‐ESR Technique

Influence of Mid‐Chain Radicals on Acrylate Free Radical Polymerization: Effect of Ester Alkyl Group

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