Search results for "nanoparticle"
showing 10 items of 2198 documents
Halloysite Nanotubes for Cleaning, Consolidation and Protection
2017
Herein, we report our recent research concerning the development of halloysite based protocols for cleaning, consolidation and protection purposes. Surface modification of halloysite cavity by anionic surfactants was explored to fabricate inorganic micelles able to solubilize hydrophobic contaminants. Hybrid dispersions based on halloysite and ecocompatible polymers were tested as consolidants for paper and waterlogged archaeological woods. Encapsulation of deacidifying and flame retardant agents within the halloysite lumen was conducted with aim to obtain nanofiller with a long-term protection ability. The results prove the suitability and versatility of halloysite nanotubes, which are per…
Photocleavable microcapsules built from photoreactive nanospheres.
2005
We show how photo-cross-linking of nanoparticles within the micrometer-sized thin oil shell of water-oil-water emulsion droplets leads to a new species of optically addressable microcontainers. The inner water droplet of these emulsions may contain drugs, dyes, or other water-soluble components, leading to filled containers. The thickness, mechanical stability, and light resistance of the container walls can be controlled in a simple way by the amount and adjustable photoreactivity of the nanoparticles. Importantly, the chemical bonds between the nanoparticles constituting the microcapsule shell can be cleaved photochemically by irradiation with UV light. This optically controlled destructi…
Alignment of Tellurium Nanorods via a Magnetization−Alignment− Demagnetization (“MAD”) Process Assisted by an External Magnetic Field
2009
Tellurium (Te) nanorods have been successfully aligned on a solid substrate via a magnetization-alignment-demagnetization ("MAD") process in the presence of an external magnetic field. Te nanorods carrying a poly(tert-butyl methacrylate) shell were first converted into magnetic nanocylinders by assembling magnetite nanoparticles on their surface via a hydrophobic interaction in THF. We demonstrate that, below a critical concentration of the nanoparticles, this assembly process is able to quantitatively tune the magnetite nanoparticles' density on the nanorods in terms of their stoichiometric ratio. Due to the polymer and surfactant on their surface, the formed magnetic nanocylinders are sol…
Enlarged pore size in nanoparticulated bimodal porous silicas: Improving accessibility
2016
Abstract Mass-transfer kinetics seems to be highly favored in siliceous materials constructed from the aggregation of mesoporous nanoparticles. Besides intra-particle mesopores, over the course of the aggregation process an inter-particle (textural) large pore system is generated. Diffusion constrains through the resulting hierarchically structured pore systems mainly depend on the characteristics of the intra-particle mesopores. By using alkanes as swelling agents, we have been able to significantly increase the intra-particle mesopore size in previously well characterized UVM-7 materials. The Winsor-III-like behavior associated with the presence of alkanes in the hydro-alcoholic reaction …
Spherical and rod-like colloids with polymer-brush surfaces
2008
In this paper, we describe a strategy to overcome incompatibility of colloidal particles and polymer coils as well as immiscibility of spherical and rod-shaped nanoparticles. Two new types of model colloids are presented, colloidal nanospheres with hairy surfaces (spherical brushes) and polymacromonomers to represent cylindrical brushes. The spherical brushes are synthesized from polyorganosiloxane-μ-gels of diameter 20 nm by grafting onto anionically prepared polystyrene macromonomers of molecular weight M w=5000 g/mol. On average, each sphere has a surface layer of 200 polymer chains. Compatibility of spherical nanoparticles with polymer coils was probed by turbidity of as-cast films as w…
Solvent Determines Nature of Effective Interactions between Nanoparticles in Polymer Brushes
2015
We study the effective interaction between two parallel rod-like nanoparticles in swollen and collapsed polymer brushes as a function of penetration depth by 2D self-consistent field calculations. In vertical direction, the interaction is always attractive. In lateral direction, the behavior under good and poor solvent conditions is qualitatively different. In swollen brushes (good solvent), nanoparticles always repel each other. In collapsed brushes (poor solvent), we identify two different regimes: an immersed regime, where the nanoparticles are fully surrounded by the brush, and an interfacial regime, where they are located in the interface between brush and solvent. In the immersed regi…
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…
Versatile Synthesis of Functional Gold Nanoparticles: Grafting Polymers From and Onto
2008
Functionalized gold nanoparticles have been prepared in an organic solvent by a two-phase reduction method in ethyl acetate and water using bis(6-hydroxyhexyl) disulfide bis(2-bromoisobutyl) ester, bis(6-acetyloxyhexyl) disulfide, and bis(5-carboxypentyl) disulfide bis(pentafluorophenyl) ester as stabilizing ligands. This procedure features the advantages that no phase transfer agent was necessary during the preparation of the gold nanoparticles and that the reducing conditions were mild enough to utilize functional disulfide ligands. The obtained gold nanoparticles with typical sizes between 2 and 5 nm could be precipitated and redispersed without any irreversible aggregation. Using these nanop…
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...
Structure of Polymer-Grafted Nanoparticle Melts.
2020
The structure of neat melts of polymer-grafted nanoparticles (GNPs) is studied via coarse-grained molecular dynamics simulations. We systematically vary the degree of polymerization and grafting density at fixed nanoparticle (NP) radius and study in detail the shape and size of the GNP coronas. For sufficiently high grafting density, chain sections close to the NP core are extended and form a dry layer. Further away from the NP, there is an interpenetration layer, where the polymer coronas of neighboring GNPs overlap and the chain sections have almost unperturbed conformations. To better understand this partitioning, we develop a two-layer model, representing the grafted polymer around an N…