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Publisher: London : Royal Soc. of Chemistry × Subject: Nanoparticles ×

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Now showing 1 - 2 of 2
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    Reorientation mechanisms of block copolymer/CdSe quantum dot composites under application of an electric field
    (London : Royal Soc. of Chemistry, 2016) Kathrein, Christine C.; Pester, Christian; Ruppel, Markus; Jung, Maike; Zimmermann, Marc; Böker, Alexander
    Time- and temperature-resolved in situ birefringence measurements were applied to analyze the effect of nanoparticles on the electric field-induced alignment of a microphase separated solution of poly(styrene)-block-poly(isoprene) in toluene. Through the incorporation of isoprene-confined CdSe quantum dots the reorientation behavior is altered. Particle loading lowers the order–disorder transition temperature, and increases the defect density, favoring nucleation and growth as an alignment mechanism over rotation of grains. The temperature dependent alteration in the reorientation mechanism is analyzed via a combination of birefringence and synchrotron SAXS. The detailed understanding of the effect of nanoparticles on the reorientation mechanism is an important prerequisite for optimization of electric-field-induced alignment of block copolymer/nanoparticle composites where the block copolymer guides the nanoparticle self-assembly into anisotropic structures.
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    Nanoscopic interactions of colloidal particles can suppress millimetre drop splashing
    (London : Royal Soc. of Chemistry, 2021) Thoraval, Marie-Jean; Schubert, Jonas; Karpitschka, Stefan; Chanana, Munish; Boyer, François; Sandoval-Naval, Enrique; Dijksman, J. Frits; Snoeijer, Jacco H.; Lohse, Detlef
    The splashing of liquid drops onto a solid surface is important for a wide range of applications, including combustion and spray coating. As the drop hits the solid surface, the liquid is ejected into a thin horizontal sheet expanding radially over the substrate. Above a critical impact velocity, the liquid sheet is forced to separate from the solid surface by the ambient air, and breaks up into smaller droplets. Despite many applications involving complex fluids, their effects on splashing remain mostly unexplored. Here we show that the splashing of a nanoparticle dispersion can be suppressed at higher impact velocities by the interactions of the nanoparticles with the solid surface. Although the dispersion drop first shows the classical transition from deposition to splashing when increasing the impact velocity, no splashing is observed above a second higher critical impact velocity. This result goes against the commonly accepted understanding of splashing, that a higher impact velocity should lead to even more pronounced splashing. Our findings open new possibilities to deposit large amount of complex liquids at high speeds.