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Penfold J, Thomas RK. The Gibbs and Butler Equations and the Surface Activity of Dilute Aqueous Solutions of Strong and Weak Linear Polyelectrolyte-Surfactant Mixtures: The Roles of Surface Composition and Polydispersity. J Phys Chem B 2024; 128:8084-8102. [PMID: 39140373 PMCID: PMC11345831 DOI: 10.1021/acs.jpcb.4c03541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 08/01/2024] [Accepted: 08/02/2024] [Indexed: 08/15/2024]
Abstract
In a previous paper, we applied a combination of direct measurements of both surface tension and surface excess in conjunction with the Gibbs equation to explain features of the adsorption and surface tension of mixtures of surfactants and strong linear polyelectrolytes at the air-water interface. This paper extends that model by including (i) the restrictions of the Butler equation for the behavior of the surface tension of mixed systems and (ii) the surface behavior of surfactant and linear weak polyelectrolyte mixtures, for which the inclusion of measurements of the surface excess and composition is shown to be particularly important. In addition, a closer examination of earlier data at higher concentrations provides evidence that the surface layering that is often observed in polyelectrolyte-surfactant systems is also an average equilibrium phenomenon and is driven by particular aggregation patterns that occur in some systems and not in others. Although the successful application of the Gibbs and Butler equations indicates that strong polyelectrolyte-surfactant systems can be described in terms of an average equilibrium over wide ranges of concentration, we have identified two concentration ranges where polydispersity in either polyelectrolyte molecular weight or composition results in significant time dependence of the surface behavior.
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Affiliation(s)
- Jeffrey Penfold
- Rutherford-Appleton
Laboratory, Chilton, Didcot, Oxfordshire OX11 0RA, U.K.
| | - Robert K. Thomas
- Physical
and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, U.K.
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Strong synergistic interactions in zwitterionic-anionic surfactant mixtures at the air-water interface and in micelles: The role of steric and electrostatic interactions. J Colloid Interface Sci 2022; 613:297-310. [PMID: 35042030 DOI: 10.1016/j.jcis.2022.01.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 11/22/2022]
Abstract
HYPOTHESIS The milder interaction with biosystems makes the zwitterionic surfactants an important class of surfactants, and they are widely used in biological applications and in personal care formulations. An important aspect of those applications is their strong synergistic interaction with anionic surfactants. It is anticipated that the strong interaction will significantly affect the adsorption and self-assembly properties. EXPERIMENTS Surface tension, ST, neutron reflectivity, NR, and small angle neutron scattering, SANS, have been used here to explore the synergistic mixing in micelles and at the air-water interface for the zwitterionic surfactant, dodecyldimethylammonium propanesulfonate, C12SB, and the anionic surfactants, alkyl ester sulfonate, AES, in the absence and presence of electrolyte, 0.1 M NaCl. FINDINGS At the air-water interface the asymmetry of composition in the strong synergistic interaction and the changes with added electrolyte and anionic surfactant structure reflect the relative contributions of the electrostatic and steric interactions to the excess free energy of mixing. In the mixed micelles the synergy is less pronounced and indicates less severe packing constraints. The micelle structure is predominantly globular to elongated, and shows a pronounced micellar growth with composition which depends strongly upon the nature of the anionic surfactant and the addition of electrolyte.
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Penfold J, Thomas RK. Neutron reflection and the thermodynamics of the air-water interface. Phys Chem Chem Phys 2022; 24:8553-8577. [PMID: 35352746 DOI: 10.1039/d2cp00053a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solution. Previously, adsorption at air-water interfaces has been determined by applying the Gibbs equation to surface tension (ST) measurements, which requires assumptions about the composition of the surface and about the activity of the solute in the bulk, which, in turn, means that in practice the surface is assumed to consist of the pure solute or of a mixture of pure solutes, and that the activity of the solute in the bulk solution is known. The use of NR in combination with ST-Gibbs measurements makes it possible to (i) avoid these assumptions and hence understand several patterns of ST behaviour previously considered to be anomalous and (ii) to start to analyse quantitatively the behaviour of mixed surfactants both below and above the critical micelle concentration. These two developments in our understanding of the thermodynamics of the air-water interface are described with recent examples.
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Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxon, UK. .,Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, UK
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Tesmar A, Kogut MM, Żamojć K, Grabowska O, Chmur K, Samsonov SA, Makowska J, Wyrzykowski D, Chmurzyński L. Physicochemical nature of sodium dodecyl sulfate interactions with bovine serum albumin revealed by interdisciplinary approaches. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Wang Z, Li P, Ma K, Chen Y, Yan Z, Penfold J, Thomas RK, Campana M, Webster JR, Li Z, Neil JH, Xu H, Petkov J, Roberts DW. α-Sulfo alkyl ester surfactants: Impact of changing the alkyl chain length on the adsorption, mixing properties and response to electrolytes of the tetradecanoate. J Colloid Interface Sci 2021; 586:876-890. [DOI: 10.1016/j.jcis.2020.10.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 11/16/2022]
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Tucker I, Burley A, Petkova R, Hosking S, Thomas R, Penfold J, Li P, Ma K, Webster J, Welbourn R. Surfactant/biosurfactant mixing: Adsorption of saponin/nonionic surfactant mixtures at the air-water interface. J Colloid Interface Sci 2020; 574:385-392. [DOI: 10.1016/j.jcis.2020.04.061] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 10/24/2022]
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Tucker IM, Burley A, Petkova RE, Hosking SL, Penfold J, Thomas RK, Li PX, Webster JRP, Welbourn R. Mixing Natural and Synthetic Surfactants: Co-Adsorption of Triterpenoid Saponins and Sodium Dodecyl Sulfate at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5997-6006. [PMID: 32388992 DOI: 10.1021/acs.langmuir.0c00922] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Saponins are highly surface active glycosides, derived from a wide range of plant species. Their ability to produce stable foams and emulsions has stimulated their applications in beverages, foods, and cosmetics. To explore a wider range of potential applications, their surface mixing properties with conventional surfactants have been investigated. The competitive adsorption of the triterpenoid saponin escin with an anionic surfactant sodium dodecyl sulfate, SDS, at the air-water interface has been studied by neutron reflectivity, NR, and surface tension. The NR measurements, at concentrations above the mixed critical micelle concentration, demonstrate the impact of the relative surface activities of the two components. The surface mixing is highly nonideal and can be described quantitatively by the pseudophase approximation with the inclusion of the quadratic and cubic terms in the excess free energy of mixing. Hence, the surface mixing is highly asymmetrical and reflects both the electrostatic and steric contributions to the intermolecular interactions. The relative importance of the steric contribution is reinforced by the observation that the micelle mixing is even more nonideal than the surface mixing. The mixing properties result in the surface adsorption being largely dominated by the SDS over the composition and concentration range explored. The results and their interpretation provide an important insight into the wider potential for mixing saponins with more conventional surfactants.
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Affiliation(s)
- I M Tucker
- Unilever Research and Development, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - A Burley
- Unilever Research and Development, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - R E Petkova
- Unilever Research and Development, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - S L Hosking
- Unilever Research and Development, Port Sunlight Laboratory, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - J Penfold
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, OXON, U.K
- Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, U.K
| | - R K Thomas
- Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, U.K
| | - P X Li
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, OXON, U.K
| | - J R P Webster
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, OXON, U.K
| | - R Welbourn
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, OXON, U.K
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Li P, Wang Z, Ma K, Chen Y, Yan Z, Penfold J, Thomas RK, Campana M, Webster JR, Washington A. Multivalent electrolyte induced surface ordering and solution self-assembly in anionic surfactant mixtures: Sodium dodecyl sulfate and sodium diethylene glycol monododecyl sulfate. J Colloid Interface Sci 2020; 565:567-581. [DOI: 10.1016/j.jcis.2020.01.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 10/25/2022]
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Penfold J, Thomas RK. Recent developments and applications of the thermodynamics of surfactant mixing. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1649489] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Jeffrey Penfold
- ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, UK
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
| | - Robert K. Thomas
- Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, UK
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Synergistic effect of surfactant compounding on improving dust suppression in a coal mine in Erdos, China. POWDER TECHNOL 2019. [DOI: 10.1016/j.powtec.2018.12.061] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Smith C, Lu JR, Thomas RK, Tucker IM, Webster JRP, Campana M. Markov Chain Modeling of Surfactant Critical Micelle Concentration and Surface Composition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:561-569. [PMID: 30540480 DOI: 10.1021/acs.langmuir.8b03624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A Markov chain (MC) model has been used to model the following binary surfactant mixtures: linear alkylbenzenesulfonate (LAS4)/octaethylene glycol monododecyl ether (C12E8) at 10 and 25 °C, LAS6/acidic sophorolipid (AS), C12Betaine/C12Maltoside, sodium lauryl ether sulfate (SLES2)/C12E8, and rhamnolipid (R1)/LAS6. The critical micellar concentration and the composition of the adsorbed layer, for each system, can be modeled using the same monomer reactivity ratio values, g1 and g2. This implies that the interactions between the surfactants in the bulk solution and at the interface are the same, within error. For the LAS4/C12E8 system at 25 °C, the ranges of g1 and g2 values which can model both sets of data are within 0.03-0.05 and 1.55-2.10, respectively; g1 ≪ g2 implies that C12E8 is significantly more surface active than LAS4. The MC model indicates a negative change in the free energy upon mixing for all of the surfactant systems, consistent with the literature. The interfacial mixing behavior of LAS4/SLES2 is inferred from the results of the MC analysis of the LAS4/C12E8 and SLES2/C12E8 systems, which share a common surfactant partner in C12E8, and the prediction is in line with the published data.
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Affiliation(s)
- Charles Smith
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Oxford Road , Manchester M13 9PL , U.K
| | - Jian Ren Lu
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Oxford Road , Manchester M13 9PL , U.K
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QZ , U.K
| | - Ian M Tucker
- Unilever Research and Development Port Sunlight Laboratory, Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - John R P Webster
- STFC , Rutherford Appleton Laboratory , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - Mario Campana
- STFC , Rutherford Appleton Laboratory , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
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Thomas RK, Penfold J. Thermodynamics of the Air–Water Interface of Mixtures of Surfactants with Polyelectrolytes, Oligoelectrolytes, and Multivalent Metal Electrolytes. J Phys Chem B 2018; 122:12411-12427. [DOI: 10.1021/acs.jpcb.8b10350] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Robert K. Thomas
- Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, U.K
| | - J. Penfold
- STFC, Rutherford-Appleton Laboratory, Chilton,
Didcot, Oxfordshire OX11 0RA, U.K
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Smith C, Lu JR, Tucker IM, Grainger D, Li P, Webster JRP, Thomas RK. Temperature Resistant Binary SLES/Nonionic Surfactant Mixtures at the Air/Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9442-9452. [PMID: 30010345 DOI: 10.1021/acs.langmuir.8b01093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Surface compositions of adsorbed monolayers at the air/water interface, formed from binary surfactant mixtures in equilibrium, have been studied using neutron reflectivity at three discrete temperatures: 10, 25, and 40 °C. The binary compositions studied are sodium lauryl dodecyl ether sulfate (SLES EO3)/C12E n, where n = 6 and 8, at a fixed concentration of 2 mM with and without the addition of 0.1 M NaCl. Without NaCl, the nonionic surfactant dominates at the interface and nonideal mixing behavior is observed. This is modeled using the pseudophase approximation with a quadratic expansion of the free energy of mixing. The addition of 0.1 M NaCl screens the charge interaction between the surfactants and drives the surface composition of each system closer to that of the bulk composition. However, model fits to both the micelles and surface layers suggest that nonideal mixing is still taking place, although it is difficult to establish the extent of nonideality due to the limited data quality. The effect of temperature changes on the surface adsorption and composition of the surfactant mixtures is minimal and within error, with and without NaCl, but the critical micelle concentrations are significantly affected. This indicates the dominant influence of steric hindrances and surfactant charge interactions in determining interfacial behavior for these surfactants, relative to the temperature changes. The study also highlights the delicate effect of a relatively small change in the number of EO groups on mixing behavior.
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Affiliation(s)
- Charles Smith
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Brunswick Street , Manchester M13 9PL , U.K
| | - Jian R Lu
- Biological Physics Laboratory, School of Physics and Astronomy , University of Manchester , Schuster Building, Brunswick Street , Manchester M13 9PL , U.K
| | - Ian M Tucker
- Unilever Research and Development Port Sunlight Laboratory , Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - David Grainger
- Unilever Research and Development Port Sunlight Laboratory , Quarry Road East , Bebington , Wirral CH63 3JW , U.K
| | - Peixun Li
- Rutherford Appleton Laboratory , STFC , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - John R P Webster
- Rutherford Appleton Laboratory , STFC , Chilton, Didcot , Oxfordshire OX11 0QX , U.K
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QZ , U.K
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Xu H, Li P, Ma K, Welbourn RJ, Doutch J, Penfold J, Thomas RK, Roberts DW, Petkov JT, Choo KL, Khoo SY. Adsorption and self-assembly in methyl ester sulfonate surfactants, their eutectic mixtures and the role of electrolyte. J Colloid Interface Sci 2018; 516:456-465. [DOI: 10.1016/j.jcis.2018.01.086] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 01/22/2018] [Accepted: 01/23/2018] [Indexed: 11/24/2022]
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Zhou Q, Qin B, Wang J, Wang H, Wang F. Effects of preparation parameters on the wetting features of surfactant-magnetized water for dust control in Luwa mine, China. POWDER TECHNOL 2018. [DOI: 10.1016/j.powtec.2017.12.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Liley JR, Thomas RK, Penfold J, Tucker IM, Petkov JT, Stevenson PS, Banat IM, Marchant R, Rudden M, Webster JRP. Adsorption at the Air-Water Interface in Biosurfactant-Surfactant Mixtures: Quantitative Analysis of Adsorption in a Five-Component Mixture. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13027-13039. [PMID: 29043809 DOI: 10.1021/acs.langmuir.7b03187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The composition of the air-water adsorbed layer of a quinary mixture consisting of three conventional surfactants, octaethylene glycol monododecyl ether (C12E8), dodecane-6-p-sodium benzene sulfonate (LAS6), and diethylene glycol monododecyl ether sodium sulfate (SLE2S), mixed with two biosurfactants, the rhamnolipids l-rhamnosyl-l-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoyl, R2, and l-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoyl, R1, has been measured over a range of compositions above the mixed critical micelle concentration. Additional measurements on some of the subsets of ternary and binary mixtures have also been measured by NR. The results have been analyzed using the pseudophase approximation (PPA) in conjunction with an excess free energy, GE, that depends on the quadratic and cubic terms in the composition. The compositions of the binary, ternary, and quinary mixtures could all be fitted to two sets of interaction parameters between the pairs of surfactants, one for micelles and one for adsorption. No ternary interactions or ternary corrections were required. Because the system contains two strongly anionic surfactants, the PPA can be extended, in practice, to ionic surfactants, contrary to the prevailing view. The values of the interaction parameters show that the quinary mixture, SLE2S-LAS6-C12E8-R1-R2, which is known to be a highly effective surfactant system, is characterized by a sequence of strong surface but weak micellar interactions. About half of the minima in GE for the strong surface interactions occur well away from the regular solution value of 0.5.
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Affiliation(s)
- Jessica R Liley
- Physical and Theoretical Chemistry Laboratory , South Parks Road, Oxford OX1 3QZ, U.K
| | - Robert K Thomas
- Physical and Theoretical Chemistry Laboratory , South Parks Road, Oxford OX1 3QZ, U.K
| | - Jeffrey Penfold
- STFC, Rutherford-Appleton Laboratory , Chilton, Didcot, Oxfordshire OX11 0QX, U.K
- Physical and Theoretical Chemistry Laboratory , South Parks Road, Oxford OX1 3QZ, U.K
| | - Ian M Tucker
- Unilever Research and Development Laboratory , Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - Jordan T Petkov
- Unilever Research and Development Laboratory , Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - Paul S Stevenson
- Unilever Research and Development Laboratory , Port Sunlight, Quarry Road East, Bebington, Wirral CH63 3JW, U.K
| | - Ibrahim M Banat
- School of Biomedical Sciences, University of Ulster , Coleraine BT52 1SA, Northern Ireland
| | - Roger Marchant
- School of Biomedical Sciences, University of Ulster , Coleraine BT52 1SA, Northern Ireland
| | - M Rudden
- School of Biomedical Sciences, University of Ulster , Coleraine BT52 1SA, Northern Ireland
| | - John R P Webster
- STFC, Rutherford-Appleton Laboratory , Chilton, Didcot, Oxfordshire OX11 0QX, U.K
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