6 Materialchemie
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- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (18) (entfernen)
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Ultra-SAXS can enhance the capabilities of existing SAXS/WAXS beamlines and laboratory instruments. A compact Ultra-SAXS module has been developed, which extends the measurable q-range with 0:0015 < q 1/nm) < 0:2, allowing structural dimensions between 30 < D(nm) < 4000 to be probed in addition to the range covered by a high-end SAXS/WAXS instrument. By shifting the module components in and out on their respective motor stages, SAXS/WAXS measurements can be easily and rapidly interleaved with USAXS measurements.
Eleventh canSAS Meeting: International Cooperation and Collaboration in Small-Angle Scattering
(2019)
The eleventh canSAS workshop was held in Freising, Germany, July 8–10, 2019.
These international meetings, promoting collective action for nomadic small-angle scatterers, have been taking place since 1998 and act as forums to catalyze cooperation amongst the SAS community in order to provide better facilities and equipment, combined with reliable data interpretation and analysis. The meeting attracted over 60 participants from major neutron and X-ray laboratories, as well as manufacturers of SAXS equipment, and users from academia and industry. There was also a wide geographical spread with participants from Australia, Asia, and North America joining European colleagues.
Zinc oxide nanostructures possess optical properties that are dependent on particle shape and size. Here, we report on the synthesis of elongated zinc oxide tubes via the in-situ aggregation of spherical particles. Using a custom-built, lab-based instrument, x-ray scattering can be investigated over more than three decades in scattering vector q, allowing for a complete investigation from atomic distances up to larger-than-nano structures.
For this study, the hydrolytic synthesis of stearate stabilized zinc oxide nanostructures in tetrahydrofuran was performed and the reaction mixture was continuously fed through the SAXS/WAXS apparatus by means of a peristaltic pump. For comparison to nanospheres, oleate-functionalized zinc oxide particles were synthesized in a microwave-assisted fashion, and depending on reaction temperature, sphere radii could be adjusted between 2.6 and 3.8 nm, changing the optical and crystal lattice properties.
The evaluation of the in-situ measurements showed that at the beginning of the synthesis of the stearate-stabilized zinc oxide, similar, spherical particles are formed as in the oleate-based synthesis. In contrast, as the reaction progresses, the stearate-capped particles aggregate into elongated rods with radii of a few nanometres, which eventually form the nanotubes. These have radii of 30-50 nm and lengths of several hundred nanometres. Nevertheless, these structures still possess optical properties like the ultra-small zinc oxide spheres, i.e. a bright, yellow fluorescence. Therefore, we assume that the originally formed, ultra-small spheres, are still present within the tube structure, but separated by stearate, and thus determine their fluorescence properties.
A look inside nanoparticles
(2019)
Small-angle scattering is the method of choice when it comes to obtaining information about the interior of nanoparticles. The aim is to make nanotechnology safer. While the use of small-angle neutron scattering (SANS) is limited to a few instruments in the world, small-angle X-ray scattering (SAXS) is widely accessible, with an upward trend. The example of core-shell particles shows how simple their analysis is with data from an Anton Paar laboratory system. Here, SAXS is a central tool for the development of new reference materials based on poly(methyl) acrylate-PVDF core-shell particles. The dimensions of the cores and shells can be precisely determined. A detailed analysis makes it possible to show that the cores contain fluorinated and nonfluorinated polymers, whereas the shell consist only of PVDF. This core-shell particles with a diameter around 40 nm show a significantly higher PVDF beta phase content than the PVDF homopolymer when using an emulsion polymerization technique. This finding is of importance with respect to applications in electroactive devices.
3D microstructures with sub-micron resolution can be manufactured in additive manner applying multi-photon laser structuring technique. This paper is focused on the incorporation of superparamagnetic iron oxide nanoparticles into the photoresist in order to manufacture micrometer-sized devices featuring a magnetic moment. The aim of the project is to achieve untethered actuation of the presented objects through externally applied magnetic fields. Future medical application scenarios such as drug delivery and tissue engineering are targeted by this research.
No matter whether you are doing X-ray diffraction or scattering, at wide or small angles, in a lab or at a synchrotron, you will need a bespoke sequence of up to twenty different corrections before it gets about right (at our latest count). Our library now does this automatically and reliably to get you the data you deserve – in absolute units and with uncertainty estimates – without the pain. This talk will highlight the development of the modular library, the sequence and its foundation, show its applicability to real-world datasets, and highlight a possible way forward
In contrast to microplastics, little is known about nanoplastics (1 to 100 nm). In order to make the dectecability of nanoplasics more reliable, we started to develop nanoplastic reference materials. This project also aims to anser the question of how the single chain conformation of bio(polymers) changes in contact with nanoplastics. Small-angle X-ray and neutron scattering methods are suitable methods for studing this topic. Recently the soft and hard interactions between polystyrene nanoplasics and human serum albumin corona was investigated with small-angle neutron scattering. Here we concentrate on small-angle X-ray scattering as our favorite method to study how (bio)polymers change their conformation in contact with nanoplastics. The scattering of bovine serum albumin in its native state can be detected easily. The scattering pattern of this biopolymer changes dramatically when its globular stucture changes to a coil structure. Modeling of chain conformations and the calculation of the scattering pattern is relatively easy to perform. Numerous model calculations will be provided to predict the changes of conformation of single bio(polymer) chains when in conatact with nanoplastics. These predictions will be compared with recent experimenal results from in situ measurments of bio(polymers) in contact with nanoplastics. The impact of temperature, polymer concentration and salt on the single-chain conformation changes will be discussed.
Small-angle scattering (SAS) offers a reliable route to characterize the nanostructure of large amounts of material with a minimum of tedium, for example, easily extracting size distributions and volume fractions. There are a variety of analysis programs available while the evaluation of SAS measurements has been dominated by the classical curve fitting approach. SASfit represents such a classical curve fitting toolbox: it is one of the mature programs for SAS data analysis and has been available and used for many years. The latest developments will be presented and a scattering function of a mass fractal model of branched polymers in solution is provided as an example for implementing a plug-in.
Alternatively to classical curve fitting, part two presents the latest developments of the user-friendly open-source Monte Carlo regression package McSAS. The form-free Monte Carlo nature of McSAS means, it is not necessary to provide further restrictions on the mathematical form of the parameter distribution: without prior knowledge, McSAS is able to extract complex multimodal or odd- shaped parameter distributions from SAS data. The headless mode is presented by an example of operation within interactive programming environments such as a Jupyter notebook.
Zinc is an essential trace element and is ingested daily by humans, partly in dissolved form. The first contact is with saliva, in which many ions are dissolved whose solubility product with zinc can be low. This could result in compounds forming, possibly in nanoparticular form, which could have different effects on the organism than pure zinc ions. Available biopolymers, e.g. α-amylase, can in turn stabilise as-formed nanostructures.
In this study, we report on the saliva stage of the artificial digestion of zinc chloride as a model substance for zinc ions. To facilitate in situ measurements, the sample is continuously passed through a small-angle x-ray scattering (SAXS) system. This custom-made machine is capable of measuring over a wide q-range and thereby able to resolve structures from around 250 nm down to the crystal structure. It is thus an excellent tool for investigating both the particle size distribution and the atomic structure of the sample.
By curve fitting (see Figure 1), we found that shortly after addition of zinc chloride to saliva, small particles with a mean radius of 1.9 ± 0.1 nm and a distribution width of 0.6 ± 0.1 nm formed. These particles are aggregated to compact mass fractals with a fractal aggregate size of 14.7 ± 0.1 nm and a fractal dimension of 2.96 ± 0.02. Approximately 7200 single particles stick together by protein and form mass fractals, whose radii of gyration were found to be 36 ± 1 nm. To determine the compound that was formed, infrared spectroscopy was used in addition to the SAXS measurements, and zinc phosphate was identified as the product.
The environmental pollution with plastic debris is one of the great challenges scientists are facing in recent times Due to degradation by UV radiation and other environmental factors, larger pieces of plastic can decompose into microscale fragments which can enter human foodstuff through the food chain or by environmental entry Recent publications show a contamination of various food products with microplastic particles suggesting a widespread exposure Thus, orally ingested plastic particles pose a potential health risk to humans In this study, we investigated the impact of artificial digestive juices on the size and shape of the three environmentally relevant microplastic particles polystyrene (PS), polypropylene (PP) and polyvinyl chloride (PVC).