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Layered transition metal dichalcogenides contain a number of crystal defects that significantly change their properties and are beneficial or detrimental for a specific application. We have prepared defect-rich multiwalled WS2 nanotubes by reductive sulfidization of W18O49 nanowires that were obtained solvothermally from tungsten chloride in different alcohols. The synthesis of the W18O49 nanowires was monitored, and their morphological characteristics (e.g., length, rigidity, and aspect ratio) are described in detail. The effect of the morphology of the nanowires on the synthesis of WS2 nanotubes was investigated in order to obtain WS2 nanotubes that are highly solvent-dispersible. Dispersions of the WS2 nanotubes in organic solvents are very stable for several days. The nanotubes were easily functionalized with noble metal, metal oxide, and Janus-type metal@metal oxide nanoparticles. The synthesis of nanowires and nanotubes and the immobilization of the nanoparticles were demonstrated by TEM, high-resolution TEM (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX), electron diffraction (ED), XRD, and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

This work deals with the toughening effect of inorganic, fullerene-like WS 2 (IF-WS 2 ) nanoparticles (NPs) on epoxy. It has been hypothesized that this toughening effect depends on the epoxy’s cross-link density, its molecular defect fraction or its reference fracture toughness K Ic . Seven different epoxy systems were filled with 0.5% laboratory-made IF-WS 2 NPs by mass and investigated in order to analyze which material properties are determining the toughening effect. These NPs were similar to commercially available IF-WS 2 NPs, but their agglomerates could not be broken up as successfully and they yielded less toughening effect. The cross-link density of the epoxies measured via dynamic-mechanical thermal analysis agreed reasonably well qualitatively with the theoretical estimation. The glass-transition temperature and the compressive yield stress were not affected significantly by the IF-WS 2 NPs. The toughening effect of IF-WS 2 depended entirely on the curing agent type and quantity. Polyetheramine-cured epoxies behaved differently from the others in their yielding behavior, but also in the IF-WS 2 NPs’ toughening effect: While some of the investigated material properties correlate strongly with the toughening effect for polyetheramine-cured epoxies, the correlation for all investigated epoxies is rather low. Thus, none of the mentioned hypotheses could be clearly confirmed. [ABSTRACT FROM AUTHOR]