scholarly journals Tailoring the Morphology of Supraparticles by Primary Colloids with Different Shapes, Sizes and Dispersities

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 79
Author(s):  
Wonmi Shim ◽  
Chan Sik Moon ◽  
Hyeonjin Kim ◽  
Hyun Su Kim ◽  
Haoxiang Zhang ◽  
...  
Keyword(s):  
Composite Material ◽  
Colloidal Particles ◽  
Colloidal Dispersion ◽  
Colloidal Dispersions ◽  
Single Component ◽  
Promising Method ◽  
Shell Structures ◽  
Core Shell ◽  
Different Shapes ◽  
Shape And Size

Surface-templated evaporation driven (STED) method is a promising method to fabricate supraparticles with various sizes, porosities, and shapes by drying colloidal dispersion drops on liquid repellent surfaces. Until now, for the method, only spherical shaped colloidal particles have been used as primary colloids. Here, we introduce six different shapes of nano-colloidal dispersions for the STED method: nanocubics, nanoplates, nanosheets, coffin-shaped nanoparticles (NPs), spherical NPs, and aggregates of NPs. It is confirmed that the shape and size of the primary colloids have little effect for drying the dispersion drop when a single component colloidal dispersion is dried. For heterogeneous supraparticles with composite material assembly, still the shape of the colloids has no influences, while the size and dispersity play roles for tuning the morphology of the supraparticles. From the results, we propose a way to fabricate homogeneous mixture, core/shell, and Janus core/shell structures of the supraparticles depending on the size and dispersity of the mixture colloidal dispersion. Indeed, knowledge on the effects of types of colloids would be of great importance for tailoring supraparticles.

Application of the Edwards Model to Steric Stabilization of Nanoparticles

2003 ◽  
Vol 17 (15) ◽  
pp. 2791-2820 ◽  
Author(s):  
Jiunn-Ren Roan
Keyword(s):  
Large Particle ◽  
Colloidal Particles ◽  
Particle Separation ◽  
Colloidal Dispersion ◽  
Colloidal Dispersions ◽  
Repulsive Force ◽  
Steric Stabilization ◽  
Conformational Entropy ◽  
Standard Picture ◽  
Edwards Model

The Edwards model for polymers with excluded-volume interaction has been used to study steric stabilization of colloidal dispersions since Dolan and Edwards' work in 1975. Following the standard picture of steric stabilization since 1950s, Dolan and Edwards solved the model by treating the surfaces of colloidal particles as plane surfaces. Consequently, their result was also consistent with the standard picture: Reduction of conformational entropy of the adsorbed homopolymers results in a purely repulsive force that stabilizes the colloidal dispersion. Recently the Edwards model was solved without treating the spherical particle surfaces as plane surfaces. It was found that, contrary to the standard picture, the conformational entropy indeed increases and the force between particles may be either purely attractive or attractive at large particle-particle separation, repulsive at intermediate separation, and again attractive at small separation. Thus, the standard picture of steric stabilization was challenged. This review summarizes this recent progress in the theory of steric stabilization of colloidal dispersions. Reconciliation between the standard picture and the recent result, and possible directions for further research are also discussed.

Solid–liquid transition of charge-stabilized colloidal dispersions: a single-component structure-function approach

2004 ◽  
Vol 82 (5) ◽  
pp. 357-366 ◽  
Author(s):  
S Zhou
Keyword(s):  
Colloidal Particles ◽  
Hard Core ◽  
Colloidal Dispersions ◽  
Single Component ◽  
Component Structure ◽  
Liquid Transition ◽  
Screened Coulomb Potential ◽  
Solvent Molecules ◽  
Solid Liquid ◽  
Good Agreement

We have extended the Raveché–Mountain–Streett one-phasecriterion that governs the freezing of Lennard-Jones systems to a hard-core repulsive Yukawa-model (HCRYM) system. We find in the framework of the Rogers–Young (RY) approximation for an Ornstein–Zernike integral equation that an HCRYM fluid freezes when the ratio α = g(rmin)/g(rmax), where rmax is the distance corresponding to the maximum in the radial distribution function g(r) and rmin is the distance corresponding to the subsequent minimum in g(r), is approximately 0.215. To describe the freezing of charge-stabilized colloidal dispersions in electrolytes, which consist of colloidal macroions,electrolyte small ions, and solvent molecules, we employ the single-component model in which the colloidal particles interact through the effective screened Coulomb potential of Belloni. Whenthe macroion surface effective charge number is taken as an adjustable parameter, the theoretical freezing line predicted by the RY g(rmin)/g(rmax) = 0.215 Raveché–Mountain–Streett one-phase criterion is in very good agreement with the corresponding experimental data.PACS Nos.: 61.25.Em, 61.20.Gy

Polydopamine used as Hollow Capsule and Core–Shell Structures for Multiple Applications

NANO ◽  
2015 ◽  
Vol 10 (05) ◽  
pp. 1530003 ◽  
Author(s):  
Xinyu Cui ◽  
Yuanyuan Yin ◽  
Zuo Ma ◽  
Yongkui Yin ◽  
Yue Guan ◽  
...  
Keyword(s):  
Recent Progress ◽  
Colloidal Particles ◽  
Shell Structures ◽  
Core Shell ◽  
Template Removal ◽  
Precise Control ◽  
The Past ◽  
Structures And Properties ◽  
Potential Applications ◽  
Hollow Capsule

Polydopamine (PDA) capsule and core–shell structures with tailored structures and properties are of particular interests due to their multifunctions and potential applications as new colloidal structures in diverse fields. Among the available fabrication methods, PDA film onto colloidal particles followed by selective template removal has attracted extensive attention due to its advantages of precise control over the size, wall thickness and functions of the obtained capsules. The past several years has witnessed a rapid increase of research concerning the new fabrication strategies, functionalization and applications of this kind of capsules and core–shell structures, particularly in many fields such as drug delivery, catalysis, antibacterial, etc. In this review, the very recent progress of the capsule and core–shell structures based on PDA are summarized. There are basically two sections, including the fabrication process of PDA capsules, core–shell structures, and the various applications based on PDA.

Preparation and Catalysis of Inverted Core/Shell Structured Pd/Au Bimetallic Nanoparticles

2003 ◽  
Vol 56 (10) ◽  
pp. 1025 ◽  
Author(s):  
Yukihide Shiraishi ◽  
Daisuke Ikenaga ◽  
Naoki Toshima
Keyword(s):  
Shell Structure ◽  
Bimetallic Nanoparticles ◽  
Colloidal Dispersion ◽  
Colloidal Dispersions ◽  
Core Shell ◽  
Before And After ◽  
Ft Ir ◽  
Adsorbed Carbon ◽  
Novel Method ◽  
Precious Metal Ions

Reduction of two different precious metal ions by refluxing in ethanol/water in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) gave a colloidal dispersion of core/shell structured bimetallic nanoparticles. In the case of Pd and Au ions, for example, the colloidal dispersions of bimetallic nanoparticles with a Au core/Pd shell structure are produced. In contrast, it is difficult to synthesize bimetallic nanoparticles with the inverted core/shell (in this case, Pd core/Au shell) structure. Here the sacrificial hydrogen strategy has been used to construct the inverted core/shell structure, where the colloidal dispersions of Pd cores are treated with hydrogen and then the solution of the second element, Au ions, is slowly added to the dispersions. This novel method, developed by us, gave the inverted core/shell structured bimetallic nanoparticles. The Pd core/Au shell structure has been confirmed by FT-IR spectra of adsorbed carbon monoxide. The hydrogenation of methyl acrylate catalyzed by the nanoparticles before and after heat treatment was investigated as well.

scholarly journals Single-Step Green Synthesis of Highly Concentrated and Stable Colloidal Dispersion of Core-Shell Silver Nanoparticles and Their Antimicrobial and Ultra-High Catalytic Properties

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1007
Author(s):  
Azam Ali ◽  
Mariyam Sattar ◽  
Fiaz Hussain ◽  
Muhammad Humble Khalid Tareen ◽  
Jiri Militky ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Tannic Acid ◽  
Rate Constant ◽  
Catalytic Properties ◽  
Colloidal Dispersion ◽  
Alkaline Condition ◽  
Core Shell ◽  
Average Particle ◽  
Ag Nps

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH4 with a normalized rate constant (Knor = K/m) of 615.04 mL·s−1·mg−1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s−1·mg−1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.

Designing active mats based on cellulose acetate/polycaprolactone core/shell structures with different release kinetics

2021 ◽  
Vol 261 ◽  
pp. 117849 ◽  
Author(s):  
Adrián Rojas ◽  
Eliezer Velásquez ◽  
Constanza Piña ◽  
María José Galotto ◽  
Carol López de Dicastillo
Keyword(s):  
Cellulose Acetate ◽  
Release Kinetics ◽  
Shell Structures ◽  
Core Shell

scholarly journals A SERS Study of Charge Transfer Process in Au Nanorod–MBA@Cu2O Assemblies: Effect of Length to Diameter Ratio of Au Nanorods

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 867
Author(s):  
Lin Guo ◽  
Zhu Mao ◽  
Sila Jin ◽  
Lin Zhu ◽  
Junqi Zhao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Shell Structure ◽  
Shell Structures ◽  
Core Shell ◽  
Absorption Bands ◽  
Au Nanorods ◽  
The Core ◽  
Band Position ◽  
Surface Enhanced Raman ◽  
Core Shell Structure

Surface-enhanced Raman scattering (SERS) is a powerful tool in charge transfer (CT) process research. By analyzing the relative intensity of the characteristic bands in the bridging molecules, one can obtain detailed information about the CT between two materials. Herein, we synthesized a series of Au nanorods (NRs) with different length-to-diameter ratios (L/Ds) and used these Au NRs to prepare a series of core–shell structures with the same Cu2O thicknesses to form Au NR–4-mercaptobenzoic acid (MBA)@Cu2O core–shell structures. Surface plasmon resonance (SPR) absorption bands were adjusted by tuning the L/Ds of Au NR cores in these assemblies. SERS spectra of the core-shell structure were obtained under 633 and 785 nm laser excitations, and on the basis of the differences in the relative band strengths of these SERS spectra detected with the as-synthesized assemblies, we calculated the CT degree of the core–shell structure. We explored whether the Cu2O conduction band and valence band position and the SPR absorption band position together affect the CT process in the core–shell structure. In this work, we found that the specific surface area of the Au NRs could influence the CT process in Au NR–MBA@Cu2O core–shell structures, which has rarely been discussed before.

Template-free synthesis of ordered ZnO@ZnS core–shell arrays for high performance supercapacitors

2016 ◽  
Vol 45 (44) ◽  
pp. 17980-17986 ◽  
Author(s):  
Hailong Yan ◽  
Tong Li ◽  
Yang Lu ◽  
Jinbing Cheng ◽  
Tao Peng ◽  
...  
Keyword(s):  
High Performance ◽  
Shell Structures ◽  
Core Shell ◽  
Template Free

In this article, ordered ZnO@ZnS core–shell structures have been produced on a stainless mesh by a two-step approach without using a template.

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