scholarly journals Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Xingmao Jiang ◽  
Ying-Bing Jiang ◽  
Nanguo Liu ◽  
Huifang Xu ◽  
Shailendra Rathod ◽  
...  
Keyword(s):  
Corrosion Inhibition ◽  
Self Assembly ◽  
Effective Diffusion ◽  
Silica Particles ◽  
Single Step ◽  
Nanoporous Silica ◽  
Core Shell ◽  
Release Process ◽  
The Core ◽  
Release Data

Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was1.0×10−14 m2s for Ce3+compared to2.5×10−13 m2s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.

Mass Transfer Model for Coated Urea Particle in Controlling-Release Process

2012 ◽  
Vol 560-561 ◽  
pp. 1119-1125
Author(s):  
Shi Xiong Hao ◽  
Xing Yong Liu ◽  
Zu Xiao Yu
Keyword(s):  
Effective Diffusion ◽  
Correlation Coefficients ◽  
Nutrient Release ◽  
Mass Conservation ◽  
Transfer Model ◽  
Release Process ◽  
Inverse Proportion ◽  
Diffusion Controlled ◽  
Coated Urea ◽  
Release Data

Based on mass conservation and Fick’s diffusion law, a model for describing the nutrient release from coated urea particles was proposed. This model was verified by the release data of three novel paraffin- rosin coated urea in distilled water. The results indicate that the model is effective in describing and predicting the delivery behaviors for a diffusion-controlled coated- urea and their correlation coefficients R2 are 0.9976, 0.9973 and 0.9984, respectively. The model shows that the nutrient release rate for coated urea is direct proportion to effective diffusion coefficient Deff, inverse proportion to diameter’s square of urea granule and inverse proportion to the coating thickness.

The formation of colloidal copper nanoparticles stabilized by zinc stearate: one-pot single-step synthesis and characterization of the core–shell particles

2009 ◽  
Vol 11 (37) ◽  
pp. 8358 ◽  
Author(s):  
André Rittermeier ◽  
Shaojun Miao ◽  
Marie K. Schröter ◽  
Xiaoning Zhang ◽  
Maurits W. E. van den Berg ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Single Step ◽  
Zinc Stearate ◽  
Synthesis And Characterization ◽  
Core Shell ◽  
One Pot ◽  
The Core ◽  
Shell Particles

scholarly journals Formation of Giant Polymer Vesicles by Simple Double Emulsification using Block Copolymers as the Sole Surfactant

Soft Matter ◽  
2021 ◽  
Author(s):  
Mazarine Houbrechts ◽  
Lucas Caire da Silva ◽  
Anitha Ethirajan ◽  
Katharina Landfester
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Shell Structure ◽  
The Self ◽  
Amphiphilic Block Copolymers ◽  
Core Shell ◽  
The Core ◽  
Polymer Vesicles ◽  
Core Shell Structure ◽  
Double Emulsification

Polymer vesicles that mimic the function of cell membranes can be obtained through the self-assembly of amphiphilic block copolymers. The cell-like characteristics of polymer vesicles, such as the core-shell structure,...

scholarly journals Effect of calcination atmosphere on structural, optical and photocatalytic activity of TiO2/SnS2 core-shell nanostructures in the reduction of aqueous Cr(VI) to Cr(III)

2021 ◽  
Vol 15 (1) ◽  
pp. 58-68
Author(s):  
Shalini Sikdar ◽  
Tiju Thomas ◽  
Rao Ramachandra ◽  
Subramshu Bhattacharya
Keyword(s):  
Photocatalytic Activity ◽  
Single Step ◽  
Visible Range ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Important Means ◽  
Calcination Atmosphere ◽  
Core Shell Nanoparticles

Conversion of Cr(VI) to Cr(III) in mitigating pollution of water bodies is of significant importance to public health due to the fact that Cr(VI) is known to be a potent carcinogen, while Cr(III) is relatively low in toxicity. Photocatalytic approaches are considered as important means to achieve this reduction. Here, TiO2/SnS2 core-shell nanostructures have been produced using a single-step hydrothermal method and its photocatalytic activity is tested for the reduction of aqueous Cr(VI). The structural and optical properties of the as-synthesized products are characterized by XRD, HRTEM, Raman, FTIR, XPS and DRS techniques. The present work reveals that by calcining the core-shell nanoparticles in Ar atmosphere a defective Ti3O5 phase is formed as the core with low band gap, and hence, offers improved light absorption in the visible range. However, its photoactivity was found to be lower than that of the core-shell nanoparticles annealed in oxidizing atmosphere. The observed lower photoreduction was due to the presence of midgap states which acted as recombination centres and hence, reduced the photocatalytic activity.

scholarly journals Characterizing the Core-Shell Architecture of Block Copolymer Nanoparticles with Electron Microscopy: A Multi-Technique Approach

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1656
Author(s):  
Vitalii Tkachenko ◽  
Loïc Vidal ◽  
Ludovic Josien ◽  
Marc Schmutz ◽  
Julien Poly ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Block Copolymer ◽  
Self Assembly ◽  
Morphological Characterization ◽  
Spherical Particles ◽  
Core Shell ◽  
Positive Staining ◽  
Particle Volume ◽  
Core Diameter ◽  
The Core

Electron microscopy has proved to be a major tool to study the structure of self-assembled amphiphilic block copolymer particles. These specimens, like supramolecular biological structures, are problematic for electron microscopy because of their poor capacity to scatter electrons and their susceptibility to radiation damage and dehydration. Sub-50 nm core-shell spherical particles made up of poly(hydroxyethyl acrylate)–b–poly(styrene) are prepared via polymerization-induced self-assembly (PISA). For their morphological characterization, we discuss the advantages, limitations, and artefacts of TEM with or without staining, cryo-TEM, and SEM. A number of technical points are addressed such as precisely shaping of particle boundaries, resolving the particle shell, differentiating particle core and shell, and the effect of sample drying and staining. TEM without staining and cryo-TEM largely evaluate the core diameter. Negative staining TEM is more efficient than positive staining TEM to preserve native structure and to visualize the entire particle volume. However, no technique allows for a satisfactory imaging of both core and shell regions. The presence of long protruding chains is manifested by patched structure in cryo-TEM and a significant edge effect in SEM. This manuscript provides a basis for polymer chemists to develop their own specimen preparations and to tackle the interpretation of challenging systems.

scholarly journals The Core/Shell Structure of CdSe/ZnS Quantum Dots Characterized by X-Ray Absorption Fine Spectroscopy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Huijing Wei ◽  
Jing Zhou ◽  
Linjuan Zhang ◽  
Fang Wang ◽  
Jianqiang Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Shell Structure ◽  
Single Step ◽  
Organic Sulfur ◽  
Core Shell ◽  
X Ray ◽  
The Core ◽  
Absorption Fine ◽  
Core Shell Structure ◽  
X Ray Absorption

Understanding the chemical and physical properties of core/shell nanocrystal quantum dots (QDs) is key for their use in light-emission applications. In this paper, a single-step injection-free scalable synthetic method is applied to prepare high-quality core/shell QDs with emission wavelengths of 544 nm, 601 nm, and 634 nm. X-ray absorption fine structure spectra are used to determine the core/shell structure of CdSe/ZnS quantum dots. Moreover, theoretical XANES spectra calculated by FEFF.8.20 are used to determine the structure of Se and S compounds. The QD samples displayed nearly spherical shapes with diameters of approximately 3.4 ± 0.5 nm (634 nm), 4.5 ± 0.4 nm (601 nm), and 5.5 ± 0.5 nm (544 nm). With XANES results and MS calculations, it is indicated that sphalerite ZnS capped with organic sulfur ligands should be the shell structure. Wurtzite CdSe is the main core structure with a Cd-Se bond length of 2.3 Å without phase shift. This means that different emission wavelengths are only due to the crystal size with single-step injection-free synthesis. Therefore, single-step injection-free synthesis could generate a nearly ideal core/shell structure of CdSe/ZnS QDs capped with an organic sulfur ligand.

Self-Assembly and Graft Polymerization Route to Monodispersed Fe3O4@SiO2—Polyaniline Core–Shell Composite Nanoparticles: Physical Properties

2008 ◽  
Vol 8 (11) ◽  
pp. 5632-5639 ◽  
Author(s):  
Kakarla Raghava Reddy ◽  
Kwang-Pill Lee ◽  
Ju Young Kim ◽  
Youngil Lee
Keyword(s):  
Magnetic Nanoparticles ◽  
Self Assembly ◽  
Magnetic Particles ◽  
Graft Polymerization ◽  
Photoelectron Spectra ◽  
Core Shell ◽  
X Ray ◽  
Pl Spectra ◽  
The Core ◽  
Modified Magnetic Nanoparticles

This study describes the synthesis of monodispersed core–shell composites of silica-modified magnetic nanoparticles and conducting polyaniline by self-assembly and graft polymerization. Magnetic ferrite nanoparticles (Fe3O4) were prepared by coprecipitation of Fe+2 and Fe+3 ions in alkaline solution, and then silananized. The silanation of magnetic particles (Fe3O4@SiO2) was carried out using 3-bromopropyltrichlorosilane (BPTS) as the coupling agent. FT-IR spectra indicated the presence of Fe—O—Si chemical bonds in Fe3O4@SiO2. Core–shell type nanocomposites (Fe3O4@SiO2/PANI) were prepared by grafting polyaniline (PANI) on the surface of silanized magnetic particles through surface initiated in-situ chemical oxidative graft polymerization. The nanocomposites were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform infrared (FTIR) spectra, UV-visible spectroscopy, photoluminescence (PL) spectra, electrical conductivity and magnetic characteristics. HRTEM images of the nanocomposites revealed that the silica-modified magnetic particles made up the core while PANI made up the shell. The XPS spectrum revealed the presence of silica in the composites, and the XRD results showed that the composites were more crystalline than pure PANI. PL spectra show that composites exhibit photoluminescent property. Conductivity of the composites (6.2 to 9.4 × 10−2 S/cm) was higher than that of pristine PANI (3.7 × 10−3 S/cm). The nanocomposites exhibited superparamagnetism. Formation mechanism of the core–shell structured nanocomposites and the effect of modified magnetic nanoparticles on the electro-magnetic properties of the Fe3O4@SiO2/PANI nanocomposites are also investigated. This method provides a new strategy for the generation of multi-functional nanocomposites that composed of other conducting polymers and metal nanoparticles.

Direct synthesis of core–shell MFI zeolites with spatially tapered trimodal mesopores via controlled orthogonal self-assembly

Nanoscale ◽  
2019 ◽  
Vol 11 (35) ◽  
pp. 16667-16676 ◽  
Author(s):  
Zhuwen Chen ◽  
Lei Dong ◽  
Chao Chen ◽  
Yanding Wang ◽  
Ya Wang ◽  
...  
Keyword(s):  
Self Assembly ◽  
Direct Synthesis ◽  
Core Shell ◽  
One Pot ◽  
The Core ◽  
Mfi Zeolites

A one-pot approach employing orthogonal self-assembly afforded MFI zeolites having trimodal mesopore distribution with size tapering from the surface to the core.

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