Rate of molecular transfer of allyl alcohol across an AOT surfactant layer using muon spin spectroscopy

Jayasooriya, Upali, Clayden, Nigel, Steytler, David, Peck, Jamie, Oganesyan, Vasily, Khasanov, Rustem, Scheuermann, Robert and Stoykov, Alexey (2016) Rate of molecular transfer of allyl alcohol across an AOT surfactant layer using muon spin spectroscopy. Langmuir, 32 (3). pp. 664-672. ISSN 0743-7463

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    Abstract

    The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of Transverse Field muon spin rotation (TF- μSR), Avoided Level Crossing muon spin resonance (ALC-μSR) and Monte Carlo simulations. Reverse microemulsions consist of nanometer sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, µSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulphosuccinate (Aerosol OT), with allyl alcohol (CH2=CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte-Carlo calculations of the ΔM=0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 109 s-1, placing the rate of interfacial transfer at the diffusion limit.

    Item Type: Article
    Uncontrolled Keywords: soft matter,muon spin spectroscopy,microemulsion,chemical exchange
    Faculty \ School: Faculty of Science > School of Chemistry
    University of East Anglia > Faculty of Science > Research Groups > Physical and Analytical Chemistry
    University of East Anglia > Faculty of Science > Research Groups > Biophysical Chemistry
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    Depositing User: Pure Connector
    Date Deposited: 02 Feb 2016 13:09
    Last Modified: 25 Jul 2018 11:36
    URI: https://ueaeprints.uea.ac.uk/id/eprint/56919
    DOI: 10.1021/acs.langmuir.5b03482

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