Browsing by Author "de Campo, L"

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    About the versatility of the state-of-the-art USANS instrument Kokkaburra
    (International Conference on Neutron Scattering, 2017-07-12) Rehm, C; de Campo, L
    Being opened for external users in 2014 the ultra-small-angle neutron scattering (USANS) instrument KOOKABURRA has since then proven to be a state-of-the-art instrument for the determination of large-scale structures. In our contribution we will discuss the instrument layout and highlight its performance as evidenced by successful USANS experiments on a variety of sample materials like, e.g., sulfide ore minerals, opals, and other complex systems.
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    Behaviour of single transmembrane peptides during in meso crystallization from the contrast-matched lipidic cubic phase of monoolein
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) van't Hag, L; de Campo, L; Tran, N; Sokolova, AV; Trenker, R; Call, M; Garvey, CJ; Leung., A; Darwish, TA; Krause-Heuer, AM; Knott, RB; Meikle, T; Gras, S; Drummond, CJ; Mezzenga, R; Conn, C
    In meso membrane protein crystallization within a lipidic mesophase has revolutionized the structural biology of integral membrane proteins (IMPs). High-resolution structures of these proteins are crucial to understanding fundamental cellular processes at a molecular level, and can lead to new and improved treatments for a wide range of diseases via rational drug design. However, overall success rates of the promising in meso crystallization technique remain low because of a fundamental lack of understanding about factors that promote crystal growth. In particular, to date, two decades from invention of the method, the protein-eye-view of the in meso crystallization mechanism had not been solved. We have investigated this for the first time using small-angle neutron scattering (SANS). Contrast-matching between the scattering of the lipid membrane formed by MO and the aqueous solution was used to isolate and track the scattering of single-transmembrane peptides during the growth of protein crystals in meso. No peptide enrichment was observed at the flat points of the diamond cubic QIID phase of MO in contrast to suggestions in several modeling studies. During in meso crystallization of the DAP12 peptide a decrease in form factor and a transient fluid lamellar Lα phase could be observed providing direct evidence for the proposed crystallization mechanism. Synthesis of fully deuterated MO was required for this purpose and scattering of this new material in various solvents and under a range of conditions will be described, specifically regarding the effect of the relative scattering length densities (SLD) of the headgroup, acyl chain and solvent, which can advance the use of neutron scattering with other self-assembly materials. © The Authors.
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    Challenges of kinetic measurements with a Bonse-Hart neutron diffractometer
    (International Conference on Neutron Scattering, 2017-07-12) Garvey, CJ; de Campo, L; Rehm, C; Muzny, CD; Hanley, HJM
    Here we report on kinetic studies of the structural effects of applied shear on the gelation of silica using the Bonse-Hart type double crystal diffractometer (USANS) Kookaburra (ANSTO, Lucas Heights Australia). This instrument is able to cover a range of scattering vectors, 2.8 x 10-5 Å-1 < q < 4x 10-2 Å-1. The gelation process may be viewed structurally as the aggregation of sol particles into larger fractal aggregates, which then form a percolative network (final gel). In previous SANS work, it was shown that shear interrupted the formation of the network, inducing a new, shear dependent structure where there are structural changes on the micron length scale. Here we use USANS to understand the structural pathway that the gel follows to the steady shear state. USANS measurements are made point by point with each rotation step of the analyzer crystal (rocking curve), with counting statistics aimed at resolving a signal above the background. To gather a comprehensive rocking curve, a single measurement will take of the order of hours, putting the ability to cover interesting kinetics beyond the realm of an ordinary beamtime allocation. Here, USANS measurements were made on the gelling system, where each measurement consists of a restricted number of points in the rocking curve, with points selected according to their ability to characterize the intermediate structure.
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    Crystallographic characterization of fluorapatite glass-ceramics synthesized from industrial waste
    (Cambridge University Press, 2017-09-15) Loy, CW; Matori, KA; Zainuddin, N; Whitten, AE; Rehm, C; de Campo, L; Sokolova, AV; Schmid, S
    A series of phase transformations of a novel fluoroaluminosilicate glass forming a range of fluorapatite glass-ceramics on sintering are reported. The sintering process induces formation of fluorapatite, mullite, and anorthite phases within the amorphous silicate matrices of the glass-ceramics. The fluoroaluminosilicate glass, SiO2–Al2O3–P2O5–CaO–CaF2, is prepared from waste materials, such as rice husk ash, pacific oyster shells, and disposable aluminium cans. The thermally induced crystallographic and microstructure evolution of the fluoroaluminosilicate glass towards the fluorapatite glass-ceramics, with applications in dental and bone restoration, are investigated by powder X-ray diffraction and small-angle neutron-scattering techniques. © Cambridge University Press.
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    Design and synthesis of an azobenzene–betaine surfactant for photo-rheological fluids
    (Elsevier, 2021-07-15) Butler, CSG; King, JP; Giles, LW; Marlow, JB; Vidallon, MLP; Sokolova, AV; de Campo, L; Tuck, KL; Tabor, RF
    Hypothesis Morphology of surfactant self-assemblies are governed by the intermolecular interactions and packing constraints of the constituent molecules. Therefore, rational design of surfactant structure should allow targeting of the specific self-assembly modes, such as wormlike micelles (WLMs). By inclusion of an appropriate photo-responsive functionality to a surfactant molecule, light-based control of formulation properties without the need for additives can be achieved. Experiments A novel azobenzene-containing surfactant was synthesised with the intention of producing photo-responsive wormlike micelles. Aggregation of the molecule in its cis and trans isomers, and its concomitant flow properties, were characterised using UV–vis spectroscopy, small-angle neutron scattering, and rheological measurements. Finally, the fluids capacity for mediating particle diffusion was assessed using dynamic light scattering. Findings The trans isomer of the novel azo-surfactant was found to form a viscoelastic WLM network, which transitioned to inviscid ellipsoidal aggregates upon photo-switching to the cis isomer. This was accompanied by changes in zero-shear viscosity up to 16,000x.UV–vis spectroscopic and rheo-SANS analysis revealed interactions of the trans azobenzene chromophore within the micelles, influencing aggregate structure and contributing to micellar rigidity. Particles dispersed in a 1 wt% surfactant solution showed a fivefold increase in apparent diffusion coefficient after UV-irradiation of the mixture. Crown Copyright © 2021 Published by Elsevier Inc.
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    Determining the location of encapsulated peptides, proteins, and other biomolecules in contrast-matched lipid bicontinuous cubic phases using SANS
    (International Conference on Neutron Scattering, 2017-07-12) van't Hag, L; de Campo, L; Gras, S; Drummond, CJ; Conn, C
    To evolve biological and biomedical applications of hybrid biomolecule?lipid materials, including in meso protein crystallization and drug delivery, an understanding of the location of the biomolecules within the bicontinuous cubic phases is crucial. Theoretical modeling has indicated that proteins and additive lipids might phase separate locally and adopt a preferred location in the cubic phase, but this has never been experimentally confirmed. We have shown that perfectly contrast-matched cubic phases in D2O can be studied using SANS by mixing fully deuterated and hydrogenated lipid. The model transmembrane peptide WALP21 showed no preferential location in the membrane of the diamond and gyroid cubic phases of phytanoyl monoethanolamide [L. van ‘t Hag et al, J. Phys. Chem. Lett. 2016, 7(14), 2862-2866]. In addition, this result opens up the possibility of studying the conformation (and hence function) of amphiphilic proteins and peptides within a lipid bilayer environment. The effect of deuteration on the cubic phase forming lipid was also investigated to advance the use of neutron scattering techniques to study soft matter systems. Additionally, we have performed extensive characterizations of the cubic phase nanostructure subsequent to protein and peptide incorporation using synchrotron SAXS, as well as the protein and peptide secondary structures using synchrotron circular dichroism spectroscopy [L. van ‘t Hag et al, Langmuir, 2016, 32(27), 6882-6894].
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    Deuterium effects in human serum albumin with nanoparticle silica kinetics
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) White, JW; Raynes, JK; Mata, JP; Gilbert, EP; Knott, RB; de Campo, L
    Light scattering shows three stages of the interaction of 80Å radius silica nanoparticles with human serum albumin in buffered solutions. The structures formed in the fast stage, twenty minutes after mixing, have been identified in a “stopped flow” neutron small angle scattering experiment. Good scattering functions were obtained at two-minute time resolution for this phase of the interaction in D2O and H2O. pH dependent changes in structure are analysed using standard fitting programs with a minimum number of parameters. This experiment was aimed to find the structural signature of nanoparticle-protein interaction, possibly the “protein corona” supposed to be formed as a means to promote entry of nanoparticles into cells. Here we use small “engineered” nanoparticles where the indications of toxicity are strong. We show with nanometric resolution that for our system, the association is largely a form of protein-induced aggregation distinct from the protein corona hypothesis. The corona might well be the mode of interaction for small proteins and nanoparticles 10-100 times larger than we have studied, but measurements on widely used commercial products may be more relevant.
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    H2O/D2O contrast variation for ultra-small-angle neutron scattering to minimize multiple scattering effects of colloidal particle suspensions
    (MDPI, 2018-09-07) Otsuki, A; de Campo, L; Garvey, CJ; Rehm, C
    This study investigated the use of solvent contrast (H2O/D2O ratio) as a means to optimize the ultra-small-angle neutron scattering (USANS) signal. By optimizing the signal, it was possible to reduce the undesirable effects of coherent multiple scattering while still maintaining a measurable scattered intensity. This result will further enable the use of USANS as a probe of the interactions between colloidal particles and their structures within concentrated suspensions as well as particle dispersion/aggregation. As a model system, we prepared silica colloidal particle suspensions at different solid concentrations. USANS curves were measured using the classical Bonse–Hart double crystal diffractometer while varying the scattering length density of the aqueous phase, thus varying the contrast to the silica particles. As a means of assessing the impact of multiple scattering effects on different q-values, we analyzed the scattered intensity at different contrasts at three different q values. The data were then used to determine the match point of the silica particle suspensions from the expected square root dependence of the scattered intensity with solvent composition, to analyze any differences associated with the solid concentration change, and to determine the optimum H2O/D2O ratio in terms of high transmission (TSAS > 80%) and high enough scattering intensity associated with the contrast of the system. Through this investigation series, we confirmed that adjusting the contrast of the solvent (H2O/D2O) is a good methodology to reduce multiple scattering while maintaining a strong enough scattering signal from a concentrated suspension of silica particles for both USANS and rheometric USANS (rheo-USANS) experiments.© The Authors - This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
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    Hierarchcial structure of solid lipid nanoparticles
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Shah, R; Mata, JP; Bryan, G; Ife, A; Karpe, A; Jadhav, S; Eldridge, D; Palombo, E; Harding, I; de Campo, L
    Suspensions of solid lipid nanoparticles (SLNs) stabilized with emulsifiers have been extensively investigated as drug carriers since the 1990s, although details of their ultrastructure are poorly de fined. Previously, our group reported a novel microwave-assisted microemulsion-based technique Page 22 ANBUG-AINSE Neutron Scattering Symposium, AANSS 2018 / Book of Abstracts to prepare SLNs. Ultrastructure generally relates to interior of the particle and can relate to internal partitioning through, for example, a core-shell structure. It can also relate to the formulation itself, including the particle itself, but can also include structures such as micelles, which may be simultaneously present. Our previous investigations revealed that SLNs were prepared by the novel microemulsion technique have size of 200-300 nm. Preliminary multi-angle SLS/DLS studies indicated core-shell type of SLNs. To understand the detailed ultrastructure of these SLNs, ultra-small angle neutron scattering (USANS) and small angle neutron scattering (SANS) experiments were conducted on suspensions of hydrogenated stearic acid SLNs stabilized with hydrogenated Tween 20 surfactant in D2O. Together, SANS and USANS gave a combined Q range of 4.7 × 10^-5 to 6 × 10^-1 Å^−1 (corresponding to a size range of ~ 1 nm - 15 µm). This extended Q range allows a comprehensive understanding of the hierarchical structure of SLNs. The SANS/USANS data are consistent with the multi-length scale structure of SLNs having polydispersed large particles at the microscale level, intermediate between spheres to rod, with roughened surfaces. At the nanoscale level, the results are consistent with the SLNs solution having an ellipsoidal shape intermediate between spheres and rods, with a crossover from mass fractals to surface fractals. The elucidation of this structure is particularly important given that the structure influences the stability and drug release properties of the nanoparticles. These results will assist in the development of systems with desired shape and properties. © The Authors.
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    Hierarchical architecture of cellulose and its interaction with other plant cell wall polysaccharides
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-18) Martínez-Sanz, M; Lopez-Sanchez, P; Mikkelsen, D; Flanagan, BM; Gidley, MJ; de Campo, L; Rehm, C; Gilbert, EP
    Plant cell walls (PCWs) are extremely complex structures in which cellulose microfibrils are hier archically assembled and embedded in a multi-component matrix. While the cellulose microfibrils represent the basic building unit providing mechanical strength [1], the matrix components are able to tune the properties of each specific tissue [2-3], increasing the flexibility or limiting the transport of moisture, for instance. The synthesis of cellulose hydrogels by means of bacterial fermentation is an efficient approach to mimic the cell wall biosynthesis process and investigate the interactions established between cellu lose and matrix polysaccharides by incorporating the latter into the culture medium. We have char acterised cellulose hydrogels and their composites with PCW polysaccharides by means of SANS and SAXS, combined with complementary techniques such as X-ray diffraction, spectroscopy and microscopy. Furthermore, the production of partially deuterated cellulose hydrogels by using a deuterated glucose-based feedstock is presented as a strategy to enhance the neutron scattering length density contrast [4]. The application of a multi-technique characterisation approach enabled elucidation of the complex hierarchical architecture of cellulose hydrogels and led to the development of a multi-scale model based on core-shell structures [4-8]. The model describes the multi-phase structure of cellulose microfibrils and ribbons, as well as the essential role of water at the different structural levels. In addition, USANS experiments are presented as a promising method to characterise the structure of native cellulose in the longitudinal direction, providing information on the microfibril length and ribbon twisting periodicity. PCW polysaccharides such as xyloglucan, arabinoxylan, mixed linkage glucans and pectins during cellulose synthesis have a distinct structural role and interaction mechanism with cellulose (interfering with the crystallisation process and strongly interacting with the cellulose microfibrils, or establishing interactions at the ribbons’ surface level). These results highlight the ability of small angle scattering techniques to provide valuable insights on cellulose biosynthesis and interactions with PCW polysaccharides. © The Authors.
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    Ionic liquid based nanoparticle emulsions as a corrosion inhibitor
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Mata, JP; Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in a miniemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nm were fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy [1]. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitor in a self-assembled nanophase particle (SNAP) coating. The corrosion protection ability of the resultant coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection [1].
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    Ionic liquid based nanoparticle emulsions as a corrosion inhibitor
    (International Conference on Neutron Scattering, 2017-07-12) Mata, JP; Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in aminiemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nmwere fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electronmicroscopy, and transmission electron microscopy [1]. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small-angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitorin a self-assembled nanophase particle (SNAP) coating. The corrosion protectionability of the resultant coating was examined using potentio dynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection [1].
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    Kookaburra, the ultra-small-angle neutron scattering instrument at ANSTO
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) de Campo, L
    The double-crystal ultra-small-angle neutron scattering (USANS) diffractometer Kookaburra at ANSTO was made available for user experiments in 2014. Kookaburra allows the characterization of microstructures covering length scales in the range of 0.1–10 μm. Use of the first- and second-order reflections coming off a doubly curved highly oriented mosaic pyrolytic graphite pre-monochromator at a fixed Bragg angle, in conjunction with two interchangeable pairs of Si(111) and Si(311) quintuple-reflection channel-cut crystals, permits operation of the instrument at two individual wavelengths, 4.74 and 2.37 Å. This unique feature among reactor-based USANS instruments allows optimal accommodation of a broad range of samples, both weakly and strongly scattering, in one sample setup [1,2]. The versatility and capabilities of Kookaburra have already resulted in a number of research papers, including studies on hard matter systems like rocks and coal [3,4], as well as soft matter systems like hydrogels, milk or worm-like micelles [5-7]. This clearly demonstrates that this instrument has a major impact in the field of large-scale structure determination. Some of the recent examples will be presented here.
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    Kookaburra, the ultra-small-angle neutron scattering instrument at ANSTO: design and recent applications
    (Australian Nuclear Science and Technology Organisation, 2021-11-25) Mata, JP; de Campo, L; Rehm, C
    The double-crystal ultra-small-angle neutron scattering (USANS) diffractometer KOOKABURRA at ANSTO was made available for user experiments in 2014. KOOKABURRA allows the characterisation of microstructures covering length scales in the range of 0.1–20 µm. Use of the first- and second-order reflections coming off a doubly curved highly oriented mosaic pyrolytic graphite pre-monochromator at a fixed Bragg angle, in conjunction with two interchangeable pairs of Si(111) and Si(311) quintuple-reflection channel-cut crystals, permits operation of the instrument at two individual wavelengths, 4.74 and 2.37 Å (see more details https://www.ansto.gov.au/our-facilities/australian-centre-for-neutron-scattering/neutron-scattering-instruments/kookaburra). This unique feature among reactor-based USANS instruments allows optimal accommodation of a broad range of samples, both weakly and strongly scattering, in one sample setup [1,2]. The versatility and capabilities of KOOKABURRA have already resulted in a number of research papers, including studies on hard matter systems like rocks and coal [3,4], as well as soft matter systems like hydrogels or milk [5,6]. This clearly demonstrates that this instrument has a major impact in the field of large-scale structure determination. Some of the recent examples will be presented here. References: [1] Rehm, C. et al, J. Appl. Cryst., 2013, 46 1699-1704. [2] Rehm, C. et al, J. Appl. Cryst., 2018, 51, 1-8. [3] Blach, T. et al, Journal of Coal Geology, 2018, 186, 135-144. [4] Sakurovs, R.et al, Energy & Fuels, 2017, 31(1), 231-238. [5] Whittaker, J. et al, Int. J. Biol. Macromol., 2018, 114, 998-1007. [6] Li, Z. et al, Food Hydrocolloid, 2018, 79, 170-178.
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    Large-scale structure investigations via neutron scattering techniques
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Rehm, C; de Campo, L
    Modern materials science and engineering relies increasingly on detailed knowledge of the microstructure and interactions in soft and hard materials. Contemporary research areas comprise, e.g., biology and the life sciences, porosity, particle sizes as well as complex fluids. At the Australian Nuclear Science and Technology Organisation (ANSTO) we apply small-angle neutron scattering (SANS) as a major technique for probing structures and interfaces of bulk samples of such substances on length scales ranging between approximately 0.001 um and 1 um using the QUOKKA [1] instrument, whereas the ultra small-angle neutron scattering (USANS) instrument KOOKABURRA [2] advances large scale structure determination of complex systems of interest in the size range of 0.1 um to 10 um. Both techniques provide information on bulk properties with minimum sample preparation, and can be used to analyse material in a non-destructive manner. This presentation will discuss SANS and USANS techniques available at ANSTO for the study of large-scale structures, and present combined SANS/USANS data sets measured on selected samples.
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    Liquid crystals with hierarchical ordering
    (International Conference on Neutron Scattering, 2017-07-12) de Campo, L; Moghaddam, M; Sokolova, AV; Rehm, C; Mittelbach, R; Varslot, T; Castle, T; Garvey, CJ; Kirby, N; Hyde, ST
    We present liquid crystal geometries experimentally found for star-polyphilic molecules as the basic building block. Star-polyphiles are small molecules, bearing three mutually immiscible chains attached to a common center [1,2,3]. Like conventional lipids or surfactants (that usually have two immisciblechains), such molecules self-assemble to form lamellar, hexagonal, micellar cubic and bicontinuous cubic structures. However, the presence of the third immiscible chain significantly increases structural complexity and hierarchical ordering can occur.
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    Microstructural evolution of dental glass-ionomer cements during setting reaction followed using SANS and USANS
    (International Conference on Neutron Scattering, 2017-07-12) Loy, CW; Matori, KA; Zainuddin, N; Whitten, AE; Rehm, C; de Campo, L; Schmid, S
    Glass-ionomer cement (GIC) is a biocompatible material which is clinically used for dental filling. The main challenges for further developing GIC in dental applications are improving the mechanical strength and controlling the setting reaction. During the setting reaction, poly (acrylic acid) attacks the fluoroaluminosilicate glass particles to form a siliceous hydrogel layer, glass core and polyalkenoate matrix in paste form. The siliceous hydrogel layer undergoes dehydration to yield a strong cross-linkage to bind both polymer and glass particles into a cement structure. This study presents the application of small angle neutron scattering (SANS) and ultra small angle neutron scattering (USANS) with contrast variation techniques to study the microstructure evolution of a complex GIC paste during 48 hours of the setting reaction. A few GIC pastes are prepared from medical grade poly (acrylic acid), SiO2–Al2O3–P2O5–Na2O–CaO–CaF2-based fluoroaluminosilicate glasses and a mixture of H2O:D2O solvent following the ISO9917-1:2007 cement preparation method. The combination of SANS (Bilby@ACNS) and USANS (Kookaburra@ACNS) provides microstructure information of GIC paste over the length scale of 1 nm to 10 µm. The microstructure change of each phase in GIC pastes is investigated at different contrast conditions by varying the H2O:D2O ratio for both neutron scattering experiments. The macro- and nano-scale features of the polymer-glass-hydrogel phases in GIC paste during the setting reaction as well as their impact on mechanical strengths are presented in this study.
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    Oil-in-water emulsion system stabilized by emulsion droplets coated with whey protein microgels
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Cheng, LR; Ye, AJ; Hemar, Y; Single, H; Gilbert, EP; de Campo, L; Whitten, AE
    Structurally designed emulsions are a developing group that is likely to find increasing utilization within the food industry because of their potential advantages over conventional emulsions. A novel droplet-stabilized (DS) emulsion system emulsified with casein micelles has been previously reported [1]. However, the mechanism of DS emulsion formation, physicochemical properties, and stability are not yet been fully explored. In the present study, heat-induced whey protein microgel (WPM) particles were used as an alternative emulsifying agent. The structure of WPM particles on the formation and physicochemical properties of the primary (PE) and the DS emulsions was investigated [2]. WPM particles were prepared by heating 4 wt% whey protein isolate solution in the presence (PB) or absence (NPB) of 10 mM phosphate buffer at pH 5.9, 85°C for 45 min, followed by washing, centrifugation, and micro-fluidization. The PE coated with WPM was homogenized using 3 passes at the pressure of 250/50 bar. DS emulsions were prepared by mixing (at 30000 rev/min for 2 min) 10 wt% oil with 10, 30, or 60 wt% PE. The structure of WPM particles and emulsions were analyzed by dynamic light scattering, confocal light scattering microscopy (CLSM), transmission electronic microscopy (TEM), and the combination of small and ultra-small angle neutron scattering (SANS and USANS). The results showed that the WPM particles produced in the absence of phosphate buffer (WPM-NPB) were smooth spherical particles, giving a surface fractal dimension of 2.0 and a hydrodynamic diameter of 270 nm. However, WPM particles made in the presence of phosphate buffer (WPM-PB) were rough spherical particles with a surface fractal dimension of 2.3 and a hydrodynamic diameter of 290 nm. Particle fragments present in the WPM-PB dispersion, resulted in their competitive adsorption onto the surface of the DS emulsions; reducing the adsorption of PE droplets. For the PE coated with WPM-NPB particles (PE-NPB), flocculation due to protein bridging and protein intramolecular interaction, lead to a network with a fractal dimension of 2.7. For the DS emulsions stabilized by PE-NPB, the interfacial layer thickness of DS emulsion droplets increased with the increase in the concentration of PE as observed by CLSM, whereas the size of DS emulsion droplets decreased. A fractal network consisting of adsorbed PE droplets on the interfacial layer of DS emulsion was observed by TEM and measured by USANS with a fractal dimension of 3.0, suggesting a very rough interface. These results suggest that both the structure of the interfacial layer and the size of the DS emulsion is dependent on the concentration of the PE used.
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    Polymeric ionic liquid nanoparticle emulsions as a corrosion inhibitor in anticorrosion coatings
    (American Chemical Society, 2016-07-06) Taghavikish, M; Subianto, S; Dutta, NK; de Campo, L; Mata, JP; Rehm, C; Choudhury, NR
    In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol–ene photopolymerization in a miniemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nm were fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small-angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitor in a self-assembled nanophase particle (SNAP) coating. The corrosion protection ability of the resultant coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection. Open Access © 2016 American Chemical Society
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    SANS time-of-flight instrument Bilby at ACNS, ANSTO
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Sokolova, AV; Whitten, AE; de Campo, L
    ANSTO for more than ten years successfully operates Small Angle Neutron Scattering (SANS) instrument Quokka [1] and in 2016 commenced user operation of the second SANS instrument, Bilby [2]. Ultra-small angle scattering machine Kookaburra [3] is completing the set of the SANS instruments at ANSTO. Bilby exploits neutron Time-of-Flight (ToF) to extend the measurable Q-range, over and above what is possible on a conventional reactor-based monochromatic SANS instrument. In ToF mode, the choppers are used to create neutron pulses of variable (~3% ‒ 30%) wavelength resolution. Two arrays of position-sensitive detectors in combination with utilizing of wide wavelength range provide the capability to collect scattering data of wide angular diapason without changing the experimental set-up (maximum accessible Q on the instrument is 0.001-1.8Å-1). Additionally to the ToF, Bilby can operate in monochromatic mode. The question is how the advanced design features can be applied to the real scientific questions. In short, having a large dynamic range available in one go opens up a possibility to study complex systems like micelles and hierarchical materials. Additionally, there is a range of sample environments available allowing to change conditions in situ, which is priceless for study a range of samples stretching from colloids to metals. In my presentation, I will be giving several examples demonstrating how ToF SANS can bring light to structural changes of the surfactant wormlike micelles structure under various conditions. Some cases will be presented to show that the monochromatic mode is also the one producing valuable results. The main accent will be made on a recently published work, done solely on Bilby along with examples of combining SANS and USANS techniques. © The authors.