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Embedding nanoparticles in a responsive polymer matrix is a formidable way to fabricate hybrid materials with predesigned properties and prospective applications in actuators, mechanically tunable optical elements, and electroclinic films. However, achieving chemical compatibility between nanoparticles and organic matter is not trivial and often results in disordered structures. Herein, it is shown that using nanoparticles as exclusive cross-linkers in the preparation of liquid-crystalline polymers can yield long-range-ordered liquid-crystalline elastomers with high loadings of well-dispersed nanoparticles, as confirmed by small-angle XRD measurements. Moreover, the strategy of incorporating NPs as cross-linking units does not result in disruption of mechanical properties of the polymer, and this phenomenon was explained by the means of all-atom molecular dynamics simulations. Such materials can exhibit switchable behavior under thermal stimulus with stability spanning over multiple heating/cooling cycles. The presented strategy has proven to be a promising approach for the preparation of new types of hybrid liquid-crystalline elastomers that can be of value for future photonic applications. [ABSTRACT FROM AUTHOR]

Understanding how the spatial ordering of liquid crystalline nanoparticles can be controlled by different factors is of great importance in the further development of their photonic applications. In this paper, we report a new key parameter to control the mesogenic behavior of gold nanoparticles modified by rodlike thiols. An efficient method to control the spatial arrangement of hybrid nanoparticles in a condensed state is developed by changing the composition of the mesogenic grafting layer on the surface of the nanoparticles. The composition can be tuned by different conditions of the ligand exchange reaction. The thermal and optical behavior of the mesogenic and promesogenic ligands were investigated by using differential scanning calorimetry (DSC) and hot-stage polarized optical microscopy. The chemical structure of the synthesized hybrid nanoparticles was characterized by 1H NMR spectroscopy, thermogravimetric analysis (TGA), XPS, and elemental analysis, whereas the superstructures were examined by small-angle X-ray diffraction (SAXSRD) analysis. Structural studies showed that the organic sublayer made of mesogenic ligands is denser with an increasing the average ligand number, thereby separating the nanoparticles in the liquid crystalline phases, which changes the parameters of these phases. [ABSTRACT FROM AUTHOR]

In this work the problem of upper detection limit of potentiometric sensors is addressed. Due to deviation of potentiometric plots from cationic Nernstian responses determination of analytes like silver cations in concentrations above 10−2 M is hardly possible, especially in the presence of background electrolyte containing lipophilic anions. Herein proposed approach applied classical complexing ligand, dithizone, attached to gold nanoparticles as ionophore. Immobilization on gold nanoparticles surface effectively anchores ligand molecules within the membrane phase. Thus obtained sensors are characterized with stable, Nernstian, potentiometric responses and selectivity comparable with classical membrane compositions. Moreover, due to lower formation constant of Ag+ with dithizone based ligand, herein reported sensors offer linear, Nernstian responses also in the range of high activity of AgNO3 solutions. [ABSTRACT FROM AUTHOR]

Gold nanoparticles surface modified with dithizone were applied as dedicated transducer in ion-selective electrodes. The presence of a dithizone modified gold nanoparticle layer beneath the ion-selective membrane enables tailoring of copper ion fluxes in all-solid-state copper selective potentiometric electrodes. Thus, depending on the pretreatment of the modified gold nanoparticle layer, different potentiometric responses can be obtained: from typical for systems with lowered activity of primary ions at the back side of the membrane (with super-Nernstian slope region), through low detection limit to classical ones. [ABSTRACT FROM AUTHOR]

For the first time, application of a membrane composed of gold nanoparticles decorated with complexing ligand for potentiometric sensing is shown. Gold nanoparticles drop cast from a solution form a porous structure on a substrate electrode surface. Sample cations can penetrate the gold nanoparticles layer and interact with ligand acting as a charged ionophore, resulting in Nernstian potentiometric responses. Anchoring of complexing ligand on the gold surface abolishes the necessity of ionophore application. Moreover, it opens the possibility of preparation of potentiometric sensors using chelators of significantly different selectivity patterns further enhanced by the absence of polymeric membrane matrix. This was clearly seen, for example, for gold nanoparticles stabilizing the applied ligand-dithizone-thiol conformation leading to a high potentiometric selectivity toward copper ions, much higher than that of ionophores typically used to induce selectivity for polymeric ion-selective membranes.