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Item type:Publication, Access status: with files , XPCS at the microsecond frontier: diffusion of PEGylated nanoparticles in water(Royal Society of Chemistry (RSC), 2026-04-22); ; ; Probing nanoscale transport in liquids under extreme thermodynamic conditions is essential for understanding soft matter and nanomaterials. However, accessing intrinsic microsecond dynamics of nanometre-sized objects remains challenging for synchrotron-based X-ray photon correlation spectroscopy (XPCS) because of limitations of coherent flux and detector repetition rates. Here, we investigate the diffusion of dilute polyethylene glycol (PEG)-coated gold nanoparticles dispersed in water over a wide temperature range, including water's supercooled regime using XPCS. The measured dynamics exhibit purely diffusive behaviour, with relaxation rates scaling as q2, and the extracted diffusion coefficients quantitatively follow the Stokes–Einstein relation with no slip boundary condition. Viscosity values derived from nanoparticle motion agree with established literature data, confirming that PEGylated nanoparticles act as reliable nanoscopic viscosity probes without evidence of ligand shell compression or structural changes. Using event-based XPCS with next-generation detectors, we access microsecond dynamics approaching the intrinsic Brownian timescale of nanometer-sized particles. These results establish PEGylated gold nanoparticles as robust probes of nanoscale transport and demonstrate the capability of advanced XPCS instrumentation to investigate fast dynamics in soft and nanoscale materials.Publicationtype: Journal Article39 50 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Metal-doped carbons from polyurea-crosslinked alginate aerogel beads(Royal Society of Chemistry (RSC), 2021-03-24); ; ; ; Metal-doped polyurea-crosslinked alginate aerogel beads (X-M-alginate; M: Ca, Co, Ni, Cu) were prepared via the reaction of an aromatic triisocyanate (Desmodur RE) with the -OH groups on the surface of pre-formed M-alginate wet gels, and with adsorbed gelation water. The X-M-alginate aerogels consisted of 49-63% polyurea and contained 2-7% metal ions; they were fibrous macro/meso/microporous materials with porosities up to 94% v/v, and BET surface areas 245-486 m2 g-1, comparable to those of native M-alginate aerogels (258-542 m2 g-1). The pyrolysis of X-M-alginate aerogels (M: Co, Ni, Cu) at 800 °C yielded carbon aerogels (X-M-C; 33-37% yield) doped with the corresponding metal (as well as with Cu2O in the case of X-Cu-C), with crystallite sizes of around 22 nm. The X-M-C aerogels retained the general fibrous morphology of their precursor (X-M-alginate) aerogels, and while X-Co-C and X-Ni-C appeared similar, the fibrous morphology of X-Cu-C was distinctly different, indicating an effect of the metal on the nanostructure of the corresponding carbon. The porosities of all X-M-C aerogels were in the range of 88-92% v/v, including macro-, meso- and micropores. Their BET surface areas were in the range of 426-541 m2 g-1, of which 208-319 m2 g-1 was allocated to micropores. In addition to the metals, XPS, Raman and FTIR analyses showed the presence of oxygen and nitrogen functionalities. Carbon in the X-M-C aerogels showed signs of stacking of graphene oxide sheets (14-15 nm), but also a low degree of graphitization and a large number of defects. This work provides a direct, inexpensive method for the preparation of fibrous metal-, oxygen- and nitrogen-doped carbon aerogels with potential for catalytic and electrochemical applications.Publicationtype: Journal ArticleScopus© Citations 16 151 247