Selection of Suitable Dispersants for Aqueous Suspensions of Zirconia and Titania Powders using Acoustophoresis

Greenwood, R.; Kendall, Kevin

doi:10.1016/s0955-2219(98)00208-8

Cited by 332 publications

(170 citation statements)

References 13 publications

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“…Zeta potential (ζ) measurements are used in order to predict the stability of dispersions. According to Greenwood et al 40 a zeta potential value higher than ±30 mV indicates that a colloidal suspension is rather stable; moderate instability is characterized by a ζ value between ±10 mV and ±30 mV while extensive coagulation/flocculation occurs for a ζ value around 0 mV.…”

Section: Resultsmentioning

confidence: 99%

Novel EDTA-ligands containing an integral perylene bisimide (PBI) core as an optical reporter unit

et al. 2014

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The synthesis, characterization and metal complexation of a new class of perylene bisimides (PBIs) as an integral part of ethylenediaminetetraacetic acid (EDTA) are reported. The simplest representative, namely derivative 1a, was synthesized both by a convergent as well as a direct approach while the elongated derivatives, 1b and 1c, were obtained only via a convergent synthetic pathway. All these new prototypes of water-soluble perylenes are bolaamphiphiles and were fully characterized by 1 H-and 13 C-NMR spectroscopy, matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and IR spectroscopy. In order to acquaint ourselves with the behaviour in solution of our PBIs bearing dendritic wedges, the simplest derivative, 1a, was chosen and tested by means of UV/Vis and fluorescence spectroscopy as well as by zeta-potential measurements. A photoexcitation induced intramolecular photo-electron transfer (PET) can be observed in these molecules. Therefore their potential applications as sensors can be imagined. Model compound 1a efficiently coordinates trivalent metal cations both in water and dimethyl sulfoxide (DMSO). Significantly, the effects of the complexation strongly depend on the aggregation state of the PBI molecules in solution. As a matter of fact, in water, the presence of M 3+ ions triggers the formation of light emitting supramolecular aggregates (excimers). On the other hand, in DMSO-rich solutions metal complexation leads to the suppression of the PET and leads to a strong fluorescence enhancement.

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Section: Resultsmentioning

confidence: 99%

Novel EDTA-ligands containing an integral perylene bisimide (PBI) core as an optical reporter unit

et al. 2014

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“…The stabilizer Na 4 P 2 O 7 is a small, highly charged molecule with P 2 O 7 4− ions adsorbing to the particle surface. As ζ increases, the suspension is electrostatically stabilized, e.g., the steric contribution to the stabilization is small [31]. Fig.…”

Section: Particle Dispersionmentioning

confidence: 96%

Distinguishing between aggregates and agglomerates of flame-made TiO2 by high-pressure dispersion

et al. 2008

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The potential of high-pressure dispersion (HPD) and dynamic light scattering (DLS) is explored for rapid and quantitative estimation of the extent of particle aggregation and agglomeration by analyzing the entire particle size distribution. Commercially available and tailor-made TiO 2 particles by flame spray pyrolysis (FSP) were characterized by X-ray diffraction, nitrogen adsorption and transmission electron microscopy (TEM). Volume distributions of these titania particles were obtained by DLS of their electrostatically stabilized (with Na 4 P 2 O 7 ) aqueous suspensions. Dispersing these suspensions through a nozzle at 200 to 1400 bar reduced the size of agglomerates (particles bonded by weak physical forces) resulting in bimodal size distributions composed of their constituent primary particles and aggregates (particles bonded by strong chemical or sinter forces). Sintering FSP-made particles from 200 to 800°C for 4 h progressively increased the minimum primary particle size (by grain growth) and aggregate size (by neck growth and phase transformation).

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“…This negative value may result from the abundant Cl − ions and indicates that the nanoparticles are stable in aqueous solution. 38,39 For more than 1 month, the solution was very stable. The surface area of the gold nanoparticles with eccentric cavities by measured by N 2 absorption-desorption isotherm Brunauer-Emmett-Teller method) was 71.2 m 2 g −1 (Section 4 of the Supplementary Information).…”

Section: Morphologymentioning

confidence: 96%

Plasmonic colloidal nanoparticles with open eccentric cavities via acid-induced chemical transformation

et al. 2015

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Surface-enhanced Raman spectroscopy (SERS) has been considered a promising technique for the detection of trace molecules in biomedicine and environmental monitoring. The ideal metal nanoparticles for SERS must not only fulfill important requirements such as high near-field enhancement and a tunable far-field response but also overcome the diffusion limitation at extremely lower concentrations of a target material. Here, we introduce a novel method to produce gold nanoparticles with open eccentric cavities by selectively adapting the structure of non-plasmonic nanoparticles via acid-mediated surface replacement. Copper oxide nanoparticles with open eccentric cavities are first prepared using a microwave-irradiation-assisted surfactant-free hydrothermal reaction and are then transformed into gold nanoparticles by an acidic gold precursor while maintaining their original structure. Because of the strong near-field enhancement occurring at the mouth of the open cavities and the very rough surfaces resulting from the uniformly covered hyperbranched sharp multi-tips and the free access of SERS molecules inside of the nanoparticles without diffusion limitation, adenine, one of the four bases in DNA, in an extremely diluted aqueous solution (1.0 pM) was successfully detected with excellent reproducibility upon laser excitation with a 785-nm wavelength. The gold nanoparticles with open eccentric cavities provide a powerful platform for the detection of ultra-trace analytes in an aqueous solution within near-infrared wavelengths, which is essential for highly sensitive, reliable and direct in vivo analysis. INTRODUCTIONThere is a strong demand for trace-molecule detection techniques that are simple, rapid, highly sensitive and reproducible, spanning from diagnostics in medicine to the detection of base sequence mutation. Surface-enhanced Raman spectroscopy (SERS) could be a promising candidate for extremely sensitive molecular finger-printing techniques that fulfill these technological and detection system criteria. 1 SERS is a near-field phenomenon that relies on the intensified electric fields (E-fields) on a metal nanostructure when its localized surface plasmon resonance is excited by light. 2 These enhanced E-fields lead to a large enhancement of the Raman scattering signal. 3 Although the hot spots exhibiting these intensively localized E-fields that are usually expected between two (or multiple) noble metal nanoparticles and the sharp nanoscale tips can amplify Raman signals by 410 6 times for trace molecule detection, 4,5 they are not easily obtained. 6,7 Several attempts have been made to increase the sensitivity and reproducibility for active SERS substrates. Two-dimensional arrays of various SERS-active substrates were introduced 8,9 but were not suitable for detection in solution or in an in vivo system because of

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Selection of Suitable Dispersants for Aqueous Suspensions of Zirconia and Titania Powders using Acoustophoresis

Cited by 332 publications

References 13 publications

Novel EDTA-ligands containing an integral perylene bisimide (PBI) core as an optical reporter unit

Novel EDTA-ligands containing an integral perylene bisimide (PBI) core as an optical reporter unit

Distinguishing between aggregates and agglomerates of flame-made TiO2 by high-pressure dispersion

Plasmonic colloidal nanoparticles with open eccentric cavities via acid-induced chemical transformation

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