Magnetic resonance measurements of solubilizate distribution coefficients and surface probabilities in some micelles

Bratt, Peter J.; Choudhury, Hasneen; Chowdhury, Parbin B.; Gillies, Donald C.; Krebber, Angelika M. L.; Sutcliffe, L. H.

doi:10.1039/ft9908603313

Cited by 12 publications

(6 citation statements)

References 6 publications

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“…For OAXS and SphiC10, the results indicate non-typical micellar conformations in accord with our previous paramagnetic enhanced relaxation studies. 42 The slow correlation times for the micelles were found to be similar to those obtained for many micellar systems. However, for the case of one micellar system (SAS-3-Cl4D3 at 20%, w/v), the micelle was found to be cylindrical and the dimensions were quantified by the use of 'H in conjunction with I3C NMR relaxation experiments.…”

Section: Discussionsupporting

confidence: 55%

NMR relaxation and ESR spin probe studies of some surfactant micelles

Bratt

Gillies

Krebber

et al. 1992

Magnetic Reson in Chemistry

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Multi-frequency relaxation studies combined with the 'two-step' and 'three-step' models for molecular motion have been applied to a range of anionic surfactant molecules. From the internal dynamic parameters (q and S) conclusions have been drawn about the dependence of surfactant molecular dynamics inside micelles on molecular structure, and two unusual conformations have been identified. Slow correlation time (2,) data have also been obtained for these compounds. Three deuteriated surfactant molecules were subjected to the 'three-step' model and data are presented showing how the dimensions of the non-spherical micelles vary with temperature. An ESR spin probe study has been carried out on the compounds giving probe rotational correlation times at various temperatures. Information on alkyl chain packing at or near the water/micelle interface can be obtained from the derived thermodynamic parameters.

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Section: Discussionsupporting

confidence: 55%

NMR relaxation and ESR spin probe studies of some surfactant micelles

Bratt

Gillies

Krebber

et al. 1992

Magnetic Reson in Chemistry

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“…Oil Phases. Determining whether spontaneously generated radicals are formed in the oil phases (particles and droplets) is made simpler by eliminating contributions to the total spontaneously generated radical flux from aqueous-phase spontaneous radical formation using a radical trap that is only soluble in the aqueous phase, viz., K 2 (SO 3 ) 2 NO (Frémy's salt, FS) . It has been found that FS does not interact with SDS-stabilized micelles , and hence by inference for droplets and particles.…”

Section: Locus Of Spontaneous Polymerizationmentioning

confidence: 99%

Spontaneous Polymerization in the Emulsion Polymerization of Styrene and Chlorobutadiene

et al. 2001

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Spontaneous initiation in emulsion polymerization may be more important than in the corresponding bulk free-radical polymerization. A methodology is derived for finding the locus of spontaneous polymerization in emulsion polymerization, through use of spin traps and catalysts which can accelerate decomposition of peroxides. Applying this to both styrene and chloroprene (chlorobutadiene), it is found that this generation occurs to some degree within all phases present. The rate of spontaneous initiation is relatively small in styrene emulsion polymerization but large in chloroprene. A means of including this effect in modeling rates and molecular weight distributions is derived, which also shows how rate parameters for the process may be obtained from experimental molecular weight distributions. This methodology is applied to these two monomers, with a series of seeded emulsion polymerizations using polystyrene host seeds for both. For styrene polymerization, the spontaneous initiation rate is low and varies with latex preparation; consistent values for this rate coefficient for a given latex are obtained by independent measurements involving two different techniques, thereby verifying the methodology. Applying this methodology to chloroprene, it is found that the effect of spontaneous initiation is much larger and probably arises from peroxides formed by exposure to oxygen. For chloroprene, spontaneous radical generation occurs both within the particles and in any monomer droplets present, with different chain-stopping mechanisms occurring in these two phases. It is a major influence on rates and molecular weight distributions, even in the presence of large amounts of added initiator; chain stoppage in droplets is largely by transfer to monomer, whereas chain stoppage within particles is by termination with short radicals formed by spontaneous initiation. Arrhenius parameters for the rate coefficient for transfer to monomer are obtained from the molecular weight distributions for the chloroprene system: k tr/dm3 mol-1 s-1 = 104.3 exp(−30.9 kJ mol-1/RT).

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“…Finally, no interaction between FS and anionic surfactants, for example, sodium dodecylsulfate (SDS), has been observed so far 44, 45. Therefore, potassium ions, originating from FS, do not lead to a loss of colloidal stability of the SDS‐stabilized latices.…”

Section: Resultsmentioning

confidence: 99%

“…So far, FS has been mostly used to investigate fundamental reaction steps in emulsion polymerization in the presence of a water‐soluble initiator, for instance, as suggested by Lacik and coworkers 43. FS is highly water‐soluble but almost insoluble in most common organic solvents 44. Therefore, the advantages of FS also include its high selectivity toward aqueous phase (carbon‐centered) radicals.…”

Section: Resultsmentioning

confidence: 99%

About crosslinking of low molecular weight ethylene‐propylene(‐diene) copolymer‐based artificial latices

Tillier

Meuldijk

Magusin

et al. 2005

J. Polym. Sci. A Polym. Chem.

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Crosslinking of artificial latices based on ethylene-propylene copolymers (EPM) and/or ethylene-propylene-diene copolymers (EPDM) has not thoroughly been studied yet. Moreover, crosslinking of EPM and/or EPDM particles is a prerequisite for the formation of a shell using seeded emulsion polymerization of, for example, methyl methacrylate (MMA), as described elsewhere. Therefore, the aim of this article is to improve the general understanding of the chemistry involved in the crosslinking process. This work especially emphasizes the influence of the initiation method, that is, a peroxide or a pulsed electron-beam, on crosslinking efficiency. All crosslinking efficiencies were obtained after extraction of the soluble polymer by tetrahydrofuran. The incorporation of the coagent, that is, divinylbenzene, into the EPM/EPDM phase was studied on a microscopic level by solid-state 13 C and 1 H nuclear magnetic resonance (NMR). Crosslinking of a low molecular weight EPM/ EPDM latex requires the presence of a coagent, for example, divinylbenzene, 1,6-hexanediol diacrylate, or poly(1,2-butadiene). The efficiency of crosslinking initiated by a pulsed electron-beam was improved to a great extent by the presence, in the aqueous phase, of potassium nitrosodisulfonate, also referred to as Fremy salt. Matrix Assisted Laser Desorption/Ionization-Time of Flight-Mass Spectrometry (MALDI-TOF-MS) was used to determine the influence of electron-beam irradiation on the chemical stability of surfactants. It was demonstrated that sodium dodecyl benzene sulfonate (SDBS) is not degraded by the irradiation, and is therefore the surfactant of choice for the stabilization of EPM/EPDM-based latices subjected to electron-beam irradiation. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3600-3615, 2005

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Magnetic resonance measurements of solubilizate distribution coefficients and surface probabilities in some micelles

Cited by 12 publications

References 6 publications

NMR relaxation and ESR spin probe studies of some surfactant micelles

NMR relaxation and ESR spin probe studies of some surfactant micelles

Spontaneous Polymerization in the Emulsion Polymerization of Styrene and Chlorobutadiene

About crosslinking of low molecular weight ethylene‐propylene(‐diene) copolymer‐based artificial latices

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