Monodisperse Hollow Spheres Research Articles

Synthesis of porous TiO2/SiO2 monodisperse hollow spheres as a platform for phosphopeptide enrichment

Synthesis of porous TiO2/SiO2 monodisperse hollow spheres as a platform for phosphopeptide enrichment

Monodisperse hollow spheres with sandwich heterostructured shells as high-performance catalysts via an extended SiO2 template method.

To improve and extend the SiO2 template method for preparing metal oxide hollow spheres, a general and facile "sol-gel and hydrothermal" method is developed to replace the current "sol-gel, calcination, and base-etching" processes for the construction of well-defined sandwich metal oxide@noble metal NP@metal oxide hollow spheres. As-synthesized hollow spheres exhibit high performances in various catalytic reactions.

Uniform and monodisperse polysilsesquioxane hollow spheres: synthesis from aqueous solution and use in pollutant removal

A series of organofunctional polysilsesquioxane hollow spheres were prepared by an environment-friendly method. The use of this simple and reproducible synthetic approach resulted in highly uniform and monodisperse hollow spheres with high coverage of functional groups, namely, fluoroalkyl, phenyl, vinyl and methyl groups. By adjusting the precursor concentration, the particle size and shell thickness could be precisely controlled. The structure and functionality of these hollow spheres were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, solid-state NMR spectroscopy, X-ray diffraction and nitrogen adsorption–desorption studies. These materials were used as adsorbents to treat the benzophenone-containing wastewater, and it was found that the hydrophobic contaminants could be effectively removed. The hydrophobic surface property of the polysilsesquioxane hollow spheres was found to be an important factor that influences the adsorption capacity.

Hollow spheres with α-cyclodextrin nanotube assembled shells

Monodisperse hollow spheres with radially oriented α-cyclodextrin nanotube assembled shells were synthesized using PEG-grafted silica as templates. (3-Aminopropyl)triethoxysilane-modified silica core was synthesized by the Stöber method and subsequently grafted with mPEG-succinimidyl carbonate through amide linkage. Maleic anhydride modified α-cyclodextrins were threaded onto the grafted-PEG chains, forming tubular polypseudorotaxanes. Adjacent polypseudorotaxanes were immobilized by crosslinking. After the extraction of the inner silica template by etching and the included PEG template by heating, hollow spheres of uniform size with α-CD nanotube assembled shells were prepared. The products were composed of intact and dispersed hollow spheres with diameter of about 50 nm, possessed uniform shell thickness of 12 nm as confirmed by transmission electron microscopy (TEM) measurement. α-CD nanotubes have a function of molecular recognization with PEG, which may endow the hollow nanospheres as promising target drug delivery vehicles by forming inclusion complexes with end-functionalized PEG.

Macroporous Silica Hollow Microspheres as Nanoparticle Collectors

In this work, we report the fabrication of macroporous silica hollow microspheres through a polystyrene (PS) templating route. Silica seeds are first deposited onto the surfaces of PS beads as a result of the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in a basic condition. Subsequent growth of silica seeds to nanoparticles with size of ∼ 40 nm leads to the coalescence of the adjacent particles, forming continuous two-dimensional silica networks on the PS surfaces. The uncovered areas on PS surfaces were converted into macrosized through holes after core removal through either dissolution or calcination, thus forming the macroporous silica hollow structures. The monodispersed hollow spheres were demonstrated to be efficient collectors for capturing and loading various nanoparticles, both hydrophilic and hydrophobic, from the external solutions. The functional particles loaded macroporous hollow spheres will have promising applications in biotechnology and catalysis.

A Novel Technique for Synthesizing Nanoshell Hollow Alumina Particles

A novel and versatile synthesis route has been developed to fabricate hollow Al2O3 microspheres with nanoporous shell structures. The method involves a preferential “implantation” of Al species into polymeric template particles to form a core–shell structure in solvent. The template cores can then be removed by thermal pyrolysis to form hollow interiors. This unique “implantation” process allows for synthesis of monodisperse hollow spheres with a nonaggregated character. The implantation of Al species is confirmed by electron spectroscopy for chemical analysis/Auger analysis in depth profiles. The shell structure changes from amorphous to γ‐Al2O3 at 900°C; because of which, the shell is nanoporous in structure. The porous shell then transforms to α‐Al2O3 as temperature is further raised above 1000°C. Transmission electron microscopy examination reveals a uniform shell thickness of ca. 20–40 nm, and grain growth appears to be constrained by the thin shell walls at 1100°C, leading to void formation at the triple grain junctions.

A Novel Method for the Fabrication of Monodisperse Hollow Silica Spheres

In this paper, we report a novel method for the fabrication of small monodisperse hollow silica spheres. In this approach, when silica shells were coated on polystyrene particles by the sol-gel method, the polystyrene cores were dissolved subsequently, even synchronously, in the same medium to form monodisperse hollow spheres. Neither additional dissolution nor a calcination process was needed to remove the polystyrene cores. Transmission electron microscopy, scanning electron microscopy, and porosity measurements were used to characterize the monodisperse hollow silica spheres.

Novel and Facile Method for the Preparation of Monodispersed Titania Hollow Spheres

The fabrication of monodispersed hollow spheres in varying sizes and shapes is very interesting and has a lot of potential applications. This paper provides a very simple route to preparing hollow titania spheres using polystyrene (PS) as a template. In this approach, the titania shells were first formed and the PS cores were dissolved subsequently, even synchronously, in the same medium; neither an additional dissolution nor a calcination process was needed to remove the PS cores. Transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Barret-Emmet-Teller measurements were used to characterize the monodispersed hollow titania spheres. A possible formation mechanism of the hollow spheres was proposed.