Diffusion in binary solutions

McCall, David W.; Douglass, D. C.

doi:10.1021/j100863a035

Cited by 194 publications

(99 citation statements)

References 4 publications

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“…They reported that the diffusion coefficient for the cobalt species was about half the diffusion coefficient of acetone. Combining this with an absolute value for the diffusion coefficient of acetone, 2.75 Â 10 À9 m 2 Á s À1 , as determined by McGall et al [48] , results in an order of magnitude of D Co ¼ 1 Â 10 À9 m 2 Á s À1 . The transfer rate coefficient can be calculated from C T ¼ 40 Â 10 3 and k p ¼ 833 L Á mol À1 Á s À1 , which results in k tr ¼ 3.3 Â 10 7 L Á mol À1 Á s À1 .…”

Section: Diffusion Controlmentioning

confidence: 70%

Solvent Effects, Diffusion Control and Mechanistic Aspects of Catalytic Chain Transfer Polymerization

Pierik¹,

Vollmerhaus²,

Herk³

2003

Macro Chemistry & Physics

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In the catalytic chain transfer polymerization of methyl methacrylate, butyl methacrylate and 2‐ethylhexyl methacrylate in toluene, it was found that the chain transfer constants (CT) were independent of solvent concentration and therefore of solution viscosity, and did not differ from the bulk polymerization values. For a diffusion controlled system, theoretical calculations predict an increase in CT when the solution viscosity is lowered. This points at a non‐diffusion controlled catalytic chain transfer step. These results were obtained when the solvent was thoroughly purified using a Grubbs‐type set‐up, whereas a large reduction in CT was found in unpurified solvent. Similar results were obtained for butyl acetate. Therefore it is concluded that the decrease of CT in non‐purified solvents is not related to the solvent itself, but to solvent impurities. Further we found that methyl methacrylate ended radicals do not covalently bind to the cobalt complex, in contrast to styrene and acrylate ended radicals.Chain transfer constant for the CCT polymerization of 2‐ethylhexyl methacrylate in toluene, and predictions for diffusion controlled systems.magnified imageChain transfer constant for the CCT polymerization of 2‐ethylhexyl methacrylate in toluene, and predictions for diffusion controlled systems.

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Section: Diffusion Controlmentioning

confidence: 70%

Solvent Effects, Diffusion Control and Mechanistic Aspects of Catalytic Chain Transfer Polymerization

Pierik¹,

Vollmerhaus²,

Herk³

2003

Macro Chemistry & Physics

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“…Relations between self-diffusion and mutual (interdiffusion) diffusion coefficients can be established, 73,74 for example, as Darken's equation 75,76 or the Hartley-Crank relation. 77,78 Since diffusion coefficients characterize the motion of particles, and the velocity of any motion is measured in some reference frame, the choice of reference frame is very important for determining diffusion coefficients. 53 The diffusion flows (or fluxes) in some arbitrary reference frame R can be written as…”

Section: Cross-diffusion Without Reactionmentioning

confidence: 99%

Cross-diffusion and pattern formation in reaction–diffusion systems

Vanag

Epstein

2009

Phys. Chem. Chem. Phys.

272

199

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Cross-diffusion, the phenomenon in which a gradient in the concentration of one species induces a flux of another chemical species, has generally been neglected in the study of reaction-diffusion systems.We summarize experiments that demonstrate that cross-diffusion coefficients can be quite significant, even exceeding ''normal,'' diagonal diffusion coefficients in magnitude in systems that involve ions, micelles, complex formation, excluded volume effects (e.g., surface or polymer reactions) and other phenomena commonly encountered in situations of interest to chemists. We then demonstrate with a series of model calculations that cross-diffusion can lead to spatial and spatiotemporal pattern formation, even in relatively simple systems. We also show that, in the absence of cross-diffusion among the reacting species, introduction of a nonreactive species that induces appropriate cross-diffusive fluxes with reactive species can lead to pattern formation.

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“…In the limit where 1 has exactly the same properties as 2, except that it is distinguishable, the situation studied in the simulations, D T1 equals the self-diffusion coefficient of the pure fluid. [7][8][9] Experimentally, this is done by using isotopically substituted solutes ͑usually radio-tracers at low concentrations͒ and extrapolating the results to that of a hypothetical tracer of the same mass as the solvent. 10 For a mixture, the D Ti for one component can be similarly extrapolated against tracer mass to give D i * of that component at its concentration in the mixture.…”

mentioning

confidence: 99%