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Synthetic colloid

Shuai Jiang, Ingo Lieberwirth, Katharina Landfester, Rafael Munoz-Espi, Daniel Crespy
We present the design of multicompartment metal oxide/silica nanofibrous photocatalysts by colloid-electrospinning and subsequent calcination. During the calcination process, silica nanomaterials are cemented to form the fibrous framework and metal oxide precursors are crystallized inside and onto the fibers. This multicompartment nanofibrous structure, constructed with nanoparticles and core-shell nanocapsules, is therefore beneficial for the separation of the materials and the light utilization due to the multiple reflections and scattering of incident light in the cavities...
August 14, 2017: Nanotechnology
Joshua J Willis, Emmett D Goodman, Liheng Wu, Andrew R Riscoe, Pedro Martins, Christopher J Tassone, Matteo Cargnello
Promoters enhance the performance of catalytic active phases by increasing rates, stability, and/or selectivity. The process of identifying promoters is in most cases empirical and relies on testing a broad range of catalysts prepared with the random deposition of active and promoter phases, typically with no fine control over their localization. This issue is particularly rele-vant in supported bimetallic systems, where two metals are co-deposited onto high-surface area materials. We here report the use of colloidal bimetallic nanocrystals to produce catalysts where the active and promoter phases are co-localized to a fine extent...
August 11, 2017: Journal of the American Chemical Society
Julie L Bitter, Yuguang Yang, Gregg Anthony Duncan, D Howard Fairbrother, Michael A Bevan
Optical microscopy is used to measure translational and rotational diffusion of colloidal rods near a single wall, confined between parallel walls, and within quasi-2D porous media as a function of rod aspect ratio and aqueous solution ionic strength. Translational and rotational diffusivities are obtained as rod particles experience positions closer to boundaries and for larger aspect ratios. Models based on position dependent hydrodynamic interactions quantitatively capture diffusivities in all geometries and indicate particle-wall separations in agreement with independent estimates based on electrostatic interactions...
August 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Taoran Wang, Jingyi Xue, Qiaobin Hu, Mingyong Zhou, Yangchao Luo
Exploitation of lipid nanoparticles for oral delivery of nutrients and drugs is limited by their poor stability under gastrointestinal tract and low loading capacity, unless a high concentration of synthetic surfactants is formulated. The main objective of present study is to design a series of new formulations for solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) that are suitable for potential oral delivery applications, using natural biopolymers, i.e. sodium caseinate (NaCas) as emulsifier and pectin as coating, with minimal addition of a synthetic surfactant, Tween 80...
July 26, 2017: Journal of Colloid and Interface Science
Maira Berenice Moreno-Trejo, Margarita Sánchez-Domínguez
The synthesis that is described in this study is for the preparation of silver nanoparticles of sizes ranging from 10 nm to 30 nm with a defined shape (globular), confirmed by UV-vis, SEM, STEM and DLS analysis. This simple and favorable one-step modified Tollens reaction does not require any special equipment or other stabilizing or reducing agent except for a solution of purified mesquite gum, and it produces aqueous colloidal dispersions of silver nanoparticles with a stability thatexceeds three months, a relatively narrow size distribution, a low tendency to aggregate and a yield of at least 95% for all cases...
October 4, 2016: Materials
Cheng Chao Li, Xianhong Rui, Weifeng Wei, Libao Chen
Multicomponent porous colloidal spheres are of interest because they not only show a combination of the properties associated with all different components, but also usually present synergy effect. However, combination of different components in a single porous sphere is still greatly challenged due to different precipitation behaviors of each component. In this work, we have developed a general synthetic route to prepare several categories of porous monodisperse RE-based colloidal spheres with customizable elemental compositions and uniform element distribution...
July 23, 2017: Chemistry: a European Journal
Francisco Monroy
From the recent advent of the new soft-micro technologies, the hydrodynamic theory of surface modes propagating on viscoelastic bodies has reinvigorated this field of technology with interesting predictions and new possible applications, so recovering its scientific interest very limited at birth to the academic scope. Today, a myriad of soft small objects, deformable meso- and micro-structures, and macroscopically viscoelastic bodies fabricated from colloids and polymers are already available in the materials catalogue...
July 18, 2017: Advances in Colloid and Interface Science
Chang Min Park, Yasir A J Al-Hamadani, Jiyong Heo, Namguk Her, Kyoung Hoon Chu, Min Jang, Sangho Lee, Yeomin Yoon
The colloidal stability of single-walled carbon nanotubes (SWNTs) sonicated at three different ultrasonication (US) frequencies (28, 580, and 1000kHz) were investigated under environmentally relevant conditions. In particular, correlations between surface chemistry, electrokinetic potential, interaction energy, and the aggregation kinetics of the aqueous SWNTs were studied. We observed that H2O2 production is negatively correlated with the yield of hydroxylation and carboxylation of SWNTs, which was dependent on the generation of ultrasonic energy by cavity collapse during US process...
November 2017: Ultrasonics Sonochemistry
Marie-Paule Pileni
The spontaneous assembly of uniform-sized globular entities into ordered arrays is a universal phenomenon observed for objects with diameters spanning a broad range of length scales. These extend from the atomic scale (10(-8) cm), through molecular and macromolecular scales with proteins, synthetic low polymers, and colloidal crystals (∼10(-6) cm), to the wavelength of visible light (∼10(-5) cm). The associated concepts of sphere packing have had an influence in diverse fields ranging from pure geometrical analysis to architectural models or ideals...
July 20, 2017: Accounts of Chemical Research
Xiaoyan Zou, Penghui Li, Jie Lou, Xiaoyan Fu, Hongwu Zhang
Silver nanoparticles (AgNPs) are increasingly used in various commercial products. This increased use raises ecological concerns because of the large release of AgNPs into the environment. Once released, the local water chemistry has the potential to influence the environmental fates and behaviors of AgNPs. The impacts of dissolved oxygen and natural organic matter (NOM) on the dissolution and stability of AgNPs were investigated in synthetic and natural freshwaters for 7 days. In synthetic freshwater, the aggregation of AgNPs occurred due to the compression of the electric double layer, accompanied by the dissolution of AgNPs...
July 14, 2017: Environmental Pollution
Karin Björklund, Loretta Li
Adsorption filtration is one of the most promising techniques for removal of dissolved, colloidal and particulate pollutants from stormwater. The aim of this study was to compare the capacity of five filter materials - cellulose, chitosan, chitosan-covered bark, pine bark, and polypropylene/polyethylene (PP/PE) fibres - to sorb organic pollutants frequently detected in stormwater, including polycyclic aromatic hydrocarbons (PAHs), alkylphenols and phthalates. In batch tests, synthetic stormwater spiked with a mixture of the organic compounds was contacted with the materials for up to 24 h...
July 13, 2017: Environmental Technology
Wen-Zhuo Zhu, Gui-Peng Yang, Hong-Hai Zhang
Chromophoric dissolved organic matter (CDOM), carbohydrates, and amino acids were analyzed to investigate the photochemistry of total dissolved (<0.22μm) organic matter (DOM), high-molecular-weight (HMW, 1kDa-0.22μm) DOM and low-molecular-weight (LMW, <1kDa) DOM at stations in the Yangtze River and its coastal area, and in the Western Pacific Ocean. Results revealed that the humic-like and tryptophan-like CDOM fluorescent components in riverine, coastal, and oceanic surface waters were photodegraded during irradiation...
July 7, 2017: Science of the Total Environment
Ryan P Bisbey, William R Dichtel
The simultaneous polymerization and crystallization of monomers featuring directional bonding designs provides covalent organic frameworks (COFs), which are periodic polymer networks with robust covalent bonds arranged in two- or three-dimensional topologies. The range of properties characterized in COFs has rapidly expanded to include those of interest for heterogeneous catalysis, energy storage and photovoltaic devices, and proton-conducting membranes. Yet many of these applications will require materials quality, morphological control, and synthetic efficiency exceeding the capabilities of contemporary synthetic methods...
June 28, 2017: ACS Central Science
Fanny Caputo, Marta Mameli, Andrzej Sienkiewicz, Silvia Licoccia, Francesco Stellacci, Lina Ghibelli, Enrico Traversa
Cerium oxide nanoparticles (CNPs) are novel synthetic antioxidant agents proposed for treating oxidative stress-related diseases. The synthesis of high-quality CNPs for biomedical applications remains a challenging task. A major concern for a safe use of CNPs as pharmacological agents is their tendency to agglomerate. Herein we present a simple direct precipitation approach, exploiting ethylene glycol as synthesis co-factor, to synthesize at room temperature nanocrystalline sub-10 nm CNPs, followed by a surface silanization approach to improve nanoparticle dispersibility in biological fluids...
July 5, 2017: Scientific Reports
Yuanyuan Wu, Zhang Luo, Bing Liu, Zhenzhong Yang
Anisotropic colloidal building blocks are quite attractive as they enable the self-assembly towards new materials with designated hierarchical structures. Although many advances have been achieved in colloidal synthetic methodology, synthesis of colloidal rings with low polydispersity and on a large scale remains a challenge. To address this issue we introduce a new site-selective growth strategy, which relies on using patchy particles. For example, by using patchy discs as templates, silica can selectively be grown on only side surfaces, resulting in formation of silica rings...
July 4, 2017: Angewandte Chemie
Bas G P van Ravensteijn, Wouter E Hendriksen, Rienk Eelkema, Jan H van Esch, Willem K Kegel
Fuel-driven assembly operates under the continuous influx of energy and results in superstructures that exist out of equilibrium. Such dissipative processes provide a route toward structures and transient behavior unreachable by conventional equilibrium self-assembly. Although perfected in biological systems like microtubules, this class of assembly is only sparsely used in synthetic or colloidal analogues. Here, we present a novel colloidal system that shows transient clustering driven by a chemical fuel. Addition of fuel causes an increase in hydrophobicity of the building blocks by actively removing surface charges, thereby driving their aggregation...
July 14, 2017: Journal of the American Chemical Society
Raffaella Buonsanti
This article presents an overview of our research in the field of colloidal nanocrystal synthesis and their implementation into water splitting and CO2 reduction electrochemical cells. We discuss our approaches to tailor-made novel material platforms to advance our knowledge in energy storage in chemical bonds, namely artificial photosynthesis. Herein, we focus on complex metal oxides as light absorbers to drive water splitting, nanocrystal hybrids and metals as electrocatalysts for carbon dioxide conversion...
November 30, 2016: Chimia
Jonathan Owen, Louis Brus
We describe the close connection between novel chemical synthesis and optimized light emission by colloidal semiconductor quantum dots (qdots). We describe how new insights and systematic improvement in synthesis and characterization have led to highly luminescent qdots that are now used in three-color liquid-crystal displays in large televisions. We outline synthetic and structural issues that require further work to enable additional applications in solar concentrators, solid-state lighting, single-photon devices, optical computing, and in vivo infrared medical imaging...
August 16, 2017: Journal of the American Chemical Society
Laura Rodríguez-Arco, Mei Li, Stephen Mann
The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). Here we report a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures...
August 2017: Nature Materials
A Shavel, L Guerrini, R A Alvarez-Puebla
Silicon nanoparticles are unique materials with applications in a variety of fields, from electronics to catalysis and biomedical uses. Despite technological advancements in nanofabrication, the development of a simple and inexpensive route for the synthesis of homogeneous silicon nanoparticles remains highly challenging. Herein, we describe a new, simple and inexpensive colloidal synthetic method for the preparation, under normal pressure and mild temperature conditions, of relatively homogeneous spherical silicon nanoparticles of either ca...
June 5, 2017: Nanoscale
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