6 Materialchemie
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You Ask – ACEnano Replies
(2020)
The workshop starts with introductory information about the workshop and the H2020 project ACEnano, followed by two expert round tables, focussing on how the project could address regulator and industry needs, respectively. This is be followed by parallel sessions on tools (based on preferences expressed by those registered to attend, see “Questions”) and finally a question-and-answer session with the attendees.
The experts invited in Round Table 1 have been prepared to answer to questions related to obstacles and advantages for stakeholders such as SMEs to use the ACEnano approaches/tools. Standardisation needs are discussed.
The principles of (Hard) X-ray photoelectron spectroscopy and some application in the field of (core-shell) nanoparticles will be presented. The presentation should answer hoe to get reliable results. Furthermore, examples of the correlation between physical-chemical measurments and toxicological results are given which are crucial for the risk assessment of nanoparticles.
The datasets from (Hard Energy) X-ray photoelectron spectroscopy, X-ray diffraction and Scanning Electron Microsopy are related to the publication
G. Chemello, X. Knigge, D. Ciornii, B.P. Reed, A.J. Pollard, C.A. Clifford, T. Howe, N. Vyas, V.-D. Hodoroaba, J. Radnik
"Influence of the morphology on the functionalization of graphene nanoplatelets analyzed by comparative photoelectron spectroscopy with soft and hard X-rays"
Advanced Materials Interfaces (2023), DOI: 10.1002/admi.202300116.
This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work.
The use of innovative near-ambient pressure (NAP-)XPS instrumentation allows the detailed analysis of irregularly-surfaced biofilms. NAP-XPS enables the surface analysis of bacterial samples in their natural hydrated state without complex sample preparation techniques such as freeze-drying or fast-freezing, which are needed for XPS analysis in ultrahigh vacuum.
XPS of GR2M
(2022)
Heterogeneous catalysis is a key technology in modern industrial societies. The main steps of a catalytic process take place at the surfaces of complex materials. For the investigations of these surfaces X-ray photoelectron spectroscopy is widely used and fits ideally. At some suitable examples, it will be explained how XPS can help to understand such catalysts better. The focus is on selective oxidation catalysts, one of the main challenges of present research. Here it will illustrate, how changes in the near surface region influence the catalyst performance and, herewith the different stages (activation, maximum performance and deactivation) in the life of catalysts. Additionally, it will be stressed out how important information at different depth regions (surface, near-surface region, bulk) can be useful for comprehensive understanding of the material.
Another important subject is nanostructured catalysts with molecular sieves as supports or defined complexes as precursors. Finally, the combination of XPS with other methods used in the analysis of catalysts, e.g. electron microscopy, X-ray absorption spectroscopy and low energy ion scattering will be discussed.
We discuss the role of the volume specific surface area (VSSA) as determined from the specific surface area measured by the (extended) Brunauer-Emmett-Teller (BET) technique, in the identification process of powdered nano- and non-nanomaterials in line with the EU definition of nanomaterial. Results obtained in the NanoDefine project demonstrate that under appropriate conditions, VSSA can be used as proxy to the number-based particle size distribution. The extent of agreement between nano/non-nano classification by electron microscopy (EM) and classification by VSSA is investigated systematically on a large set of diverse particulate substances, representing most of the cases expected in regulatory practice. Thus, parameters such as particle shape, size polydispersity/multi-modality, and particle (inner or coating) porosity are evaluated. Based on these results, we derive a tiered screening strategy for powders, involving the use of VSSA for the purpose of implementing the definition of nanomaterial, and recommend it for inclusion in a technical guidance for the implementation of the definition.
Luminescent lanthanides(III) offer exceptional optical properties that can overcome issues often encountered with other fluorophores (e.g. organic dyes). Their long lifetimes up to milliseconds, low photobleaching and sharp and characteristic emission peaks make the lanthanides extremely valuable for the development of advanced luminescent materials. Previous work on Ru(II) and Ir(III) gold surfaces further highlights the potential of employing the luminescence of metal complexes for the fabrication of sensing platforms and devices.
Here, we incorporate visible and NIR-emitting lanthanide(III) complexes Ln2L3 (Ln = Eu(III), Nd(III), Yb(III)) to gold and plasmonic surfaces, translating the unique optical properties of the lanthanides(III) to practical devices. The Ln2L3 complexes are deposited on the surfaces with different methods, ranging from polymer aided physisorption to the covalent attachment on the gold surface. Furthermore, we exploit the high sensitivity to the coordination environment of lanthanides(III) to design and prepare a sensing platform.
Thermosetting materials are gaining increasing attention in many structural composite applications. However, the incorporation of inorganic nanoparticles (NPs) into polymer matrix is a promising approach to enhance their functional characteristics, and thus, to enable the development of thermosets advanced application. It has been shown that Boehmite Alumina (BA) used as nanofillers can improve different parameters of polymers. This NPs can be easily tailored enabling desirable interactions with a big range of polymers. However, the overall effect of nanofiller depends on many factors, therefore, making it hard to predict the resulted performance of nanocomposites. In the current contribution we would like to discuss the impact of Boehmite NPs on two different epoxy resin nanocomposite systems with the focus on the possible influence mechanisms of this nanofiller.
As the first system, UV curable Cycloaliphatic-Epoxy Oligosiloxane (CEOS) resin/Boehmite nanocomposites were investigated by FTIR, TGA, DSC and T-SEM. It was observed that incorporation of BA leads to the reinforcement of glass transition (Tg) and overall thermal stability indicating the attractive interactions between BA and CEOS network. In addition, an increase in epoxy conversion of CEOS was concluded for nanocomposites assuming that particles are involved in UV polymerisation processes.
The second epoxy/Boehmite nanocomposite is based on the bisphenol-A-diglycidyl ether (DGEBA) cured with methyl tetrahydrophtalic acid anhydride (MTHPA). Thermomechanical as well as nanomechanical properties of this material were investigated by DMTA and IR spectroscopy and the advanced Intermodulation AFM, respectively. In contrast to the first system, it was found that BA leads to a decrease of Tg and crosslink density of the polymer while the young’s modulus of the composite and local stiffness of polymer matrix increase significantly.
As a result, the versatile role of Boehmite was detected depending on the investigated systems. Based on the obtained results, the parameters indicating property-efficient epoxy/Boehmite system are suggested.