Synthesis of polystyrene/polysilsesquioxane core/shell composite particles via emulsion polymerization in the existence of poly(γ-methacryloxypropyl trimethoxysilane) sol

Controllable Preparation of Monodisperse Mesoporous Silica from Microspheres to Microcapsules and Catalytic Loading of Au Nanoparticles

A unique structural transition from pomegranate-like monodisperse mesoporous silica microspheres (M-MSMs) with tunable mesopores to mesoporous silica microcapsules has been reported. The unique evolution occurred together with varying the cross-linking degrees (CLDs) of templates. Herein, using monodisperse sulfonated cross-linked polystyrene (S-CLPS) as templates, S-CLPS/SiO₂ composite microspheres were synthesized by the sol-gel method. Subsequently, the templates were removed by calcination to obtain the M-MSMs or microcapsules. The pore sizes of M-MSMs could be tailored from 3.2 to 7.4 nm by facilely varying the CLDs from 0.5 to 20%. Interestingly, mesoporous silica microcapsules were gradually formed when the CLDs were beyond 20%. Meanwhile, the specific surface area also could be adjusted by this strategy without hardly affecting the monodispersity, and the specific surface area increased to 391.9 m²/g. Significantly, Au@M-MSM was prepared by supporting Au nanoparticles (NPs) on M-MSM and used as nanocatalysts to reduce 4-nitrophenol (4-NP). The ultrathin shell and interconnected three-dimensional (3D) porous structure of M-MSMs can increase the mass transfer and protect the Au NPs from leakage, which reveals high recyclability and high conversion (>95%) after 10 regeneration-catalysis cycles. This approach provides a nanotechnology platform for the preparation of mesoporous silica materials with different microstructures, which will have enormous potential in practical applications involving different molecular sizes.

Recent advances in colloidal nanocomposite designviaheterogeneous polymerization techniques

Recent advances in colloidal nanocomposite design by heterogeneous polymerization are reviewed, with a specific focus on encapsulation and particle-based stabilization for specific materials applications.

Polymeric Nanoparticle-Coated Pickering Emulsion-Synthesized Conducting Polyaniline Hybrid Particles and Their Electrorheological Study

To produce an electric stimuli-responsive electrorheological (ER) material, semiconducting core/shell-type polyaniline (PANI) hybrid particles were fabricated through Pickering emulsion-type polymerization, using poly(divinylbenzene-alt-maleic anhydride) (PDVMA) particles as a solid surfactant. The PDVMA nanoparticles were initially polymerized using a self-stable precipitation method. The fabricated PANI/PDVMA composite particles were subjected to various chemical characterizations; further, they were suspended in silicone oil at 10 vol % to prepare an ER fluid, and their viscoelastic behaviors were scrutinized using a rheometer under various input electric fields. We also adopted an LCR meter to evaluate its dielectric characteristics. Our results showed that the PANI/PDVMA composite particles display typical ER performance, such that both dynamic and elastic yield stresses follow a polarization mechanism with a slope of 2.0.

Organosilica hybrid nanomaterials with a high organic content: syntheses and applications of silsesquioxanes

Organic-inorganic hybrid materials garner properties from their organic and inorganic matrices as well as synergistic features, and therefore have recently attracted much attention at the nanoscale. Non-porous organosilica hybrid nanomaterials with a high organic content such as silsesquioxanes (R-SiO_1.5, with R organic groups) and bridged silsesquioxanes (O_1.5Si-R-SiO_1.5) are especially attractive hybrids since they provide 20 to 80 weight percent of organic functional groups in addition to the known chemistry and stability of silica. In the organosilica family, silsesquioxanes (R-SiO_1.5) stand between silicas (SiO₂) and silicones (R₂SiO), and are variously called organosilicas, ormosil (organically-modified silica), polysilsesquioxanes and silica hybrids. Herein, we comprehensively review non-porous silsesquioxane and bridged silsesquioxane nanomaterials and their applications in nanomedicine, electro-optics, and catalysis.

Synthesis of polypyrrole–polystyrene composite microspheres via pseudo-multicomponent heterophase polymerization and the potential application on Cr(vi) removal

Polypyrrole–polystyrene (PPy–PS) composite hollow microspheres with a dry-plum-like morphology were prepared via pseudo-multicomponent heterophase polymerization in an aqueous dispersion system.

Surface Thiolation of Al Microspheres to Deposite Thin and Compact Ag Shells for High Conductivity

In this work, we have demonstrated a method for controllable thiolated functionalization coupled with electroless silver plating to achieve aluminum@silver (Al@Ag) core-shell composite particles with thin and compact layers. First, Al microspheres were functionalized by a well-known polymerizable silane coupling agent, i.e., 3-mercaptopropyltrimethoxysilane (MPTMS). Decreasing the ethanol-to-water volume ratio (F) in silane solution produces modification films with high content of thiol groups on Al microspheres, owing to the dehydration of silane molecules with hydroxyl groups on Al microspheres and self-polymerization of silane molecules. Then, ethanol was used as one of the solvents to play a major role in the uniform dispersion of silane coupling agent in the solution, resulting in uniformly distributing and covalently attaching thiol groups on Al microspheres. In electroless silver plating, thiol groups being densely grafted on the surface of Al microspheres favor the heterogeneous nucleation of Ag, since the thiol group can firmly bind with Ag(+) and enable the in situ reduction by the reducing reagent. In this manner, dense Ag nuclei tend to produce thin and compact silver shells on the Al microspheres surfaces. The as-obtained Al@Ag core-shell composite particles show a resistivity as low as (8.58 ± 0.07) × 10(-5) Ω·cm even when the Ag content is as low as 15.46 wt %. Therefore, the as-obtained Al@Ag core-shell composite particles have advantages of low weight, low silver content and high conductivity, which could make it a promising candidate for application in conductive and electromagnetic shielding composite materials.

Construction of Grape-like Silica-Based Hierarchical Porous Interlocked Microcapsules by Colloidal Crystals Templates

We present a facile strategy to prepare grape-like silica-based hierarchical porous interlocked microcapsules (HPIMs) by polystyrene colloidal crystals templates, whose structure is the subtle integration of open mouthed structure, hierarchical porous nanostructure and interlocked architecture. HPIMs are fabricated by replicating colloidal crystals templates that have a hexagonal close-packed structure; thus, theoretically, each microcapsule has 12 open mouths, and these open mouths with mesoporous microcapsule wall construct the hierarchical porous structure. Furthermore, the interlocked architecture of the microcapsules can endow HPIMs with excellent mechanical stability and recyclability. By adjusting sulfonation time, the morphology, shell thickness, and even mesporous size of the HPIMs can be precisely controlled. In addition, HPIMs with various compositions are obtained via this method, such as silica and aminopropyl polysilsesquioxane (APSQ). All these unique features derived from a readily available method will give products with a broader range of applications.

Tracking translocation of industrially relevant engineered nanomaterials (ENMs) across alveolar epithelial monolayers in vitro

Abstract Relatively little is known about the fate of industrially relevant engineered nanomaterials (ENMs) in the lungs that can be used to convert administered doses to delivered doses. Inhalation exposure and subsequent translocation of ENMs across the epithelial lining layer of the lung might contribute to clearance, toxic effects or both. To allow precise quantitation of translocation across lung epithelial cells, we developed a method for tracking industrially relevant metal oxide ENMs in vitro using neutron activation. The versatility and sensitivity of the proposed in vitro epithelial translocation (INVET) system was demonstrated using a variety of industry relevant ENMs including CeO2 of various primary particle diameter, ZnO, and SiO2-coated CeO2 and ZnO particles. ENMs were neutron activated, forming gamma emitting isotopes (141)Ce and (65)Zn, respectively. Calu-3 lung epithelial cells cultured to confluency on transwell inserts were exposed to neutron-activated ENM dispersions at sub-lethal doses to investigate the link between ENM properties and translocation potential. The effects of ENM exposure on monolayer integrity was monitored by various methods. ENM translocation across the cellular monolayer was assessed by gamma spectrometry following 2, 4 and 24 h of exposure. Our results demonstrate that ENMs translocated in small amounts (e.g. <0.01% of the delivered dose at 24 h), predominantly via transcellular pathways without compromising monolayer integrity or disrupting tight junctions. It was also demonstrated that the delivery of particles in suspension to cells in culture is proportional to translocation, emphasizing the importance of accurate dosimetry when comparing ENM-cellular interactions for large panels of materials. The reported INVET system for tracking industrially relevant ENMs while accounting for dosimetry can be a valuable tool for investigating nano-bio interactions in the future.

Synthesis and properties of hybrid core–shell poly(alkyltrialkoxysiloxane) latex

We discuss the nucleation mechanism and process of hybrid core–shell poly(alkyltrialkoxysiloxane) latex particles’ formation.