Search results for "colloid"

Scanning electrochemical microscopy and electrochemical impedance spectroscopy-based characterization of perforated polycarbonate membrane modified b…

2021

Abstract In this research, scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were applied for the evaluation of surface characteristics of electrochemical (amperometric) biosensor based on two composite structures consisting of perforated polycarbonate membrane modified by carbon-nanomaterials and glucose oxidase. The first structure consisted of the polycarbonate filter membrane, punctured by 400 nm holes (PCM) consequently modified with single walled carbon nanotubes (SWCNT) and graphene oxide (GO) layer (PCM/SWCNT/GO); and the other structure consisted of the same PCM, consequently modified with SWCNT and reduced graphene oxide (rGO) layer (PCM/S…

Stability of Halloysite, Imogolite, and Boron Nitride Nanotubes in Solvent Media

2018

Inorganic nanotubes are attracting the interest of many scientists and researchers, due to their excellent application potential in different fields. Among them, halloysite and imogolite, two naturally-occurring aluminosilicate mineral clays, as well as boron nitride nanotubes have gained attention for their proper shapes and features. Above all, it is important to reach highly stable dispersion in water or organic media, in order to exploit the features of this kind of nanoparticles and to expand their applications. This review is focused on the structural and morphological features, performances, and ratios of inorganic nanotubes, considering the main strategies to prepare homogeneous col…

Seedless assembly of colloidal crystals by inverted micro-fluidic pumping

2018

We propose a simple seedless approach to assemble millimeter sized monolayer single colloidal crystals with desired orientations at predetermined locations on an unstructured charged substrate. This approach utilizes the millimeter-ranged fluid flow on the bottom glass substrate induced by an ion exchange resin (IEX) fixed on top of the closed sample cell. This fluid flow increases with decreasing height of the sample cell and increasing radius R of the IEX. For a single inverted pump, millimeter sized monolayer single crystals of hexagonal close packing can be obtained. For two closely spaced (D ~ 4R) pumps, the formed crystals have a predefined orientation along the line connecting the tw…

Continuous‐Flow Synthesis of High‐Quality Few‐Layer Antimonene Hexagons

2021

2D materials show outstanding properties that can bring many applications in different technological fields. However, their uses are still limited by production methods. In this context, antimonene is recently suggested as a new 2D material to fabricate different (opto)electronic devices, among other potential applications. This work focuses on optimizing the synthetic parameters to produce high-quality antimonene hexagons and their implementation in a large-scale manufacturing procedure. By means of a continuous-flow synthesis, few-layer antimonene hexagons with ultra-large lateral dimensions (up to several microns) and a few nanometers thick are isolated. The suitable chemical post-treatm…

Large Photonic Films by Crystallization on Fluid Substrates

2002

Cracks, which appear due to shrinkage during drying of artificial opaline films, strongly limit the use of these materials. Crystallization on fluid substrates (liquid metals) is a way to circumvent this problem. By this method it is possible to prepare crack-free three-dimensional “monocrystals” with a very low defect density and the size in millimeters.

Switchable Light Reflectance in Dilute Magneto-Optical Colloids Based on Nickel Ferrite Nanowires

2018

Photonic effect study on polystyrene 3D-photonic crystals at near-field range: dependence on the wavelength and on the lattice parameter

2007

3D-photonic crystals (opals) based on polystyrene (PS) colloidal nanospheres are being characterized by scanning near-field optical microscopy (SNOM). These crystals offer a huge potential for controlling both the spontaneous emission of embedded light sources and the propagation of light itself.

Narrowing the Plasmonic Sensitivity Distribution by Considering the Individual Size of Gold Nanorods

2018

The plasmonic nanoparticle sensitivity, sensing volume, and the signal-to-noise ratio are strongly dependent on the nanoparticle dimensions. It is difficult to chemically produce or purify nanoparticles with a size variation of less than 10%. This size variation induces a systematic error in sensing experiments that can be reduced when the exact size of each individual nanoparticle is known. In this work, we show how the size of gold nanorods can be estimated directly from the optical spectra of single nanoparticles by using the increase of radiation damping with the nanoparticle size. We verify our approach by comparing these spectrally estimated sizes with the precise sizes of exactly the…

Dynamic light scattering by rodlike particles: [4] examination of the vanadium(V)-oxide system

1999

The dynamics of a suspension of rodlike particles has been investigated using dynamic light scattering. The sols investigated in this contribution are not monodisperse by nature and age with time. An evaluation of the first cumulant of the autocorrelation functions as a function of scattering vector is expected to yield the dimensions of the particles. While the data can be excellently fitted by the theoretical expressions for freshly prepared sols, we found that the theoretically expected interrelation of the (three) diffusion coefficients is not reproduced, which prohibits the unequivocal determination of the particle dimensions. Aged sols, on the other hand, cannot be described at all wi…

Real-space imaging and motion analysis in sheared colloidal crystals

2007

Microscopic imaging of single particles is a powerful tool to investigate the local structure of colloidal suspensions. For single-particle identification with high-resolution microscopy the resolution power is limited by refraction to roughly the wavelength of light. In this case the depth of sharpness is on a scale of less than this limit. For this reason the simultaneous observation of particles in two or more layers of a colloidal crystal seems to be impossible. We report a method with which we can image more than one particle layer in dilute colloidal suspensions with preserved resolution. The analysis of the images obtained, in particular for the investigation of crystal layer motion …