Browsing by Author "Wilkinson, BL"

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    Reversible pH- and photocontrollable carbohydrate-cased surfactants
    (Wiley Online Library, 2014-09-11) Tabor, RF; Tan, DD; Han, SS; Young, SA; Seeger, ZLE; Pottage, MJ; Garvey, CJ; Wilkinson, BL
    The parallel synthesis and properties of a library of photoswitchable surfactants comprising a hydrophobic butylazobenzene tail-group and a hydrophilic carbohydrate head-group, including the first surfactants to exhibit dual photo- and pH-responsive behavior, is reported. This new generation of surfactants shows varying micelle morphologies, photocontrollable surface tension, and pH-induced aggregation and adsorption. © 2014, WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.
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    Watching photo-sensitive surfactant micelles morph in real time using SANS
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Tabor, RF; Wilkinson, BL; Garvey, CJ
    Recent interest has surged in colloidal and self-assembling systems that can respond to internal and external stimuli. Of the possible response mechanisms, light is seen as a clean and low energy ‘reagent’ for stimulating physical and chemical changes. We have recently synthesized a library of light-addressable surfactant molecules based around the photo isomerisable azobenzene core, coupled to sugar head-groups [1]. Depending on their molecular geometry, these molecules self-assemble into a wide variety of micellar structures, from small spheres to worms, fibres and liquid crystals, and the diversity of this self-assembly is uncovered using small-angle neutron scattering. By using time-resolved SANS, we can watch as the micelles change their shape in real time as the molecules undergo photo-isomerisation, pointing to applications in the delivery of sensitive cargoes, and the modulation of biological and cellular processes.
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    Wormlike micelle formation of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants: Structure–function relationships and rheology
    (Elsevier, 2018-11-01) Moore, JE; Mccoy, TM; de Campo, L; Sokolova, AV; Garvey, CJ; Pearson, G; Wilkinson, BL; Tabor, RF
    Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Here, seven novel carbohydrate based surfactants (CBS) have been synthesized that contain a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and unsaturated (C18:1) alkyl chains. The aqueous adsorption and self-assembly of these surfactants was explored using tensiometry and small- and ultra-small-angle neutron scattering (SANS and USANS). With SANS we observed elongation from spherical to cylindrical micelles with increasing alkyl chain length. C16 and C18 chains exhibited pronounced Krafft points, yet formed worm-like micelles as single components upon heating to 43 and 48 °C respectively. The introduction of mono-unsaturation in the form of a C18:1 chain reduced the Krafft point and gave a surfactant that produced worm-like micelles in water without additives at room temperature. We also observed micellar elongation for C12 and C14 chains at 50 °C due to dehydration of the TEG linker. The room temperature worm-like micelles were further characterized using rheo-SANS and rheology, revealing the C18:1 surfactant to exhibit near ideal Maxwell behavior at low concentrations (2.9 wt.%). These results provide insight into structure-function relationships for CBS, and demonstrate a promising molecular candidate for the formation of viscoelastic worm-like micellar solutions. © 2018 Elsevier Inc.