Search results for "ARTICLES"
showing 10 items of 9626 documents
Interfacial Assembly and Jamming Behavior of Polymeric Janus Particles at Liquid Interfaces
2017
The self-assembly and interfacial jamming of spherical Janus nanoparticles (JNPs) at the water/oil interface were investigated. Polymeric JNPs, made by cross-linking polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (PS-PB-PMMA), with a high interfacial activity assemble at the water/oil interface. During the self-assembly at the interface, the interfacial energy was reduced and a dynamic interlayer was observed that is responsive to the pH of the aqueous phase. Unlike hard particles, the JNPs are composed of polymer chains that can spread at the liquid-liquid interface to maximize coverage at relatively low areal densities. In a pendant drop geometry, the interfacial area of …
Engineered Multifunctional Nanotools for Biological Applications
2011
Smart multifunctional magnetic nanoparticles are popular candidates for several biological applications owing to their intrinsic magnetic property and diverse applications that range from rare protein separation and biomedical utilization to cancer therapy and diagnostics. A universal protocol, for the development of such nanocarriers, is highly desirable for scientists with different backgrounds so that custom-made multifunctional nanoparticles can be developed to address their needs, among which are the superparamagnetic iron oxide and manganese oxide nanoparticles that are synthesized through high temperature decomposition reactions. However, an interface is needed to present these inorg…
Modification of Polymer-Magnetic Nanoparticles by Luminescent and Conducting Substances
2014
The polymer encapsulated magnetic nanoparticles were obtained by suspension polymerization of styrene in the aqueous dispersion of magnetite. Functionalization of capsules was carried out by adsorp...
Fabrication of a Silica Coating on Magnetic γ-Fe2O3 Nanoparticles by an Immobilized Enzyme
2008
Silicatein, a hydrolytic protein encountered in marine sponges, was immobilized on maghemite (γ-Fe2O3) nanoparticles that were surface functionalized with a reactive mulfunctional polymer. This polymer carries an anchor group based on dopamine which is capable of binding to the γ-Fe2O3 surface and a reactive functional group which allows binding of various biomolecules onto inorganic nanoparticles. This functional nitrilotriacetic acid (NTA) group allows immobilization of His-tagged silicatein on the surface of the γ-Fe2O3 nanoparticles. The surface-bound protein retains its native hydrolytic activity to catalyze formation of silica through copolymerization of alkoxysilanes Si(OR)4. Functio…
Expanded micro-particles by supercritical antisolvent precipitation: Interpretation of results
2008
Abstract Supercritical antisolvent (SAS) micronization has been used to obtain nanoparticles and micro-particles of several kinds of materials. Sometimes hollow expanded micro-particles have also been obtained. This work is focused on the analysis of this last morphology. We organized literature data and our previous experiments and we added new experiments on previously tested compounds and on compounds never tested before. As a result, expanded micro-particles using several compounds belonging to different categories and precipitated from different solvents in laboratory and pilot scale plants were obtained with diameters between about 10 and 180 μm. They also showed different sub-structu…
Recent Applications of Carbonaceous Nanosorbents in Solid Phase Extraction for the Determination of Pesticides in Food Samples
2018
This article covers recent trends of carbonaceous nanomaterial supported solid phase extraction for the liquid and gas chromatography analysis of pesticides in food samples. Several advanced carbonaceous nanosorbents have been reported over the previous decade for pesticide extraction, such as graphene derivatives modified by combination with silica, amines, polymers, and/or magnetic nanoparticles. The advances in this field have opened possibilities for using neat or modified carbon nanotubes or graphene-type sorbents for the pre-concentration of polar or nonpolar pesticides by solid phase extraction (SPE) or micro-SPE methods or to apply such nanomaterials for the removal of matrix compon…
How ill-defined constituents produce well-defined nanoparticles: effect of polymer dispersity on the uniformity of copolymeric micelles
2019
We investigate the effect of polymer length dispersity on the properties of self-assembled micelles in solution by self-consistent field calculations. Polydispersity stabilizes micelles by raising the free energy barriers of micelle formation and dissolution. Most importantly, it significantly reduces the size fluctuations of micelles: Block copolymers of moderate polydispersity form more uniform particles than their monodisperse counterparts. We attribute this to the fact that the packing of the solvophobic monomers in the core can be optimized if the constituent polymers have different length.
Nanoscale hybrid silica/polymer Janus particles with a double-responsive hemicorona
2015
Abstract We report a versatile large-scale synthesis strategy for hybrid Janus nanoparticles with a silica core and a unilaterally attached polymer corona in a size range below 100 nm. The stimuli-responsive behavior of these nanoparticles with a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) hemicorona is investigated. The synthesis is based on a modified version of the Pickering emulsion polymerization technique in combination with surface-initiated atom transfer radical polymerization (ATRP) in a “grafting from” approach. In a first step, poly(vinyl acetate) (PVAc) latex particles are prepared via Pickering emulsion polymerization. Colloidal stability is provided by 30 nm silica nan…
Highly cross-linked imidazolium salt entrapped magnetic particles – preparation and applications
2012
Magnetic particles entrapped into highly cross-linked imidazolium salts were synthesized using a straightforward approach by radical polymerization of bis-vinylimidazolium salts in the presence of superparamagnetic iron oxide particles. Potential applications for these new materials as (i) catalysts for conversion of propylene oxide to propylene carbonate, (ii) supports for organocatalysts, and (iii) scavenger materials for palladium removal are outlined.
Modern trends in solid phase extraction: New sorbent media
2016
Abstract Based on the recently published literature, this review provides an update of the most important features and application of formats and devices employed in solid phase extraction (SPE). Special attention was paid on new trapping media proposed in SPE prior the chromatography analysis, based on the use of nanostructured materials, including carbon nanomaterials, electrospun nanofibers, dendrimes and magnetic nanoparticles, molecular recognition sorbents, as aptamers, immunosorbents, molecular imprinted polymers, ion imprinting polymers, metal-organic frameworks and restricted access materials. Discussions on the present limitations as well as expected future trends of the new trapp…