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Composite Spheres (composite + sphere)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Preparation of Functionalized Polysilsesquioxane and Polysilsesquioxane-Metal Nanoparticle Composite Spheres,

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2006
Young Baek Kim
Abstract Summary: Network polysilsesquioxane spheres made solely of poly(vinylsilsesquioxane) (PVSQ) and poly(3-mercaptopropylsilsesquioxane) (PMPSQ) were prepared from heterogeneous mixtures of triethylamine (TEA), water, and either vinyltrimethoxysilane (VTMS), or 3-mercaptopropyltrimethoxysilane (MPTMS). The microscopic, macroscopic observations, and the relationship between the diameters of spheres and the amount of each ingredient in the reaction system, showed that spheres formed via a mechanism similar to emulsion polymerization and suspension polymerization, depending on the reaction conditions. Diameters of spheres could be controlled from tens of nanometers to a few micrometers by adjusting the amounts of TEA, water, and a surfactant. Heating aqueous solutions of metal ions with these spheres produced polysilsesquioxanes (PSQ)-metal nanoparticle composite spheres. The spheres prepared in this study were characterized by scanning electron microscopy, transmission electron microscopy, solid state NMR spectroscopy, IR spectroscopy, elemental analysis, and differential thermal analysis. These spheres would be useful in recovering metals from their ionic solutions and probes after chemical modifications. An image of the spheres of poly(vinylsilsesquioxane)-gold nanoparticle composite. [source]

Enhanced Optical Properties and Opaline Self-Assembly of PPV Encapsulated in Mesoporous Silica Spheres

ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009
Timothy L. Kelly
Abstract A new poly(p -phenylenevinylene) (PPV) composite material has been developed by the incorporation of insoluble PPV polymer chains in the pores of monodisperse mesoporous silica spheres through an ion-exchange and in situ polymerization method. The polymer distribution within the resultant colloidal particles is characterized by electron microscopy, energy dispersive X-ray microanalysis, powder X-ray diffraction, and nitrogen adsorption. It was found that the polymer was selectively incorporated into the mesopores of the silica host and was well distributed throughout the body of the particles. This confinement of the polymer influences the optical properties of the composite; these were examined by UV,vis and fluorescence spectroscopy and time-correlated single-photon counting. The results show a material that exhibits an extremely high fluorescence quantum yield (approaching 85%), and an improved resistance to oxidative photobleaching compared to PPV. These enhanced optical properties are further complemented by the overall processability of the colloidal material. In marked contrast to the insolubility of PPV, the material can be processed as a stable colloidal dispersion, and the individual composite spheres can be self-assembled into opaline films using the vertical deposition method. The bandgap of the opal can be engineered to overlap with the emission band of the polymer, which has significant ramifications for lasing. [source]

A novel and facile preparation method of hollow silica spheres containing small SiO2 cores

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2007
Xinjian Cheng
Abstract This article presents a novel and facile preparation method of hollow silica spheres with loading small silica inside. In this approach, positively charged SiO2/polystyrene core-shell composite particles were synthesized first, when the silica shells from the sol-gel process of tetraethoxysilane were then coated on the surfaces of composite particles via electrostatic interaction, the polystyrene was dissolved subsequently even synchronously in the same medium to form hollow silica spheres with small silica cores. TEM, SEM, and FTIR measurements were used to characterize these composite spheres. Based on this study, some inorganic or organic compounds could be loaded into these hollow silica spheres. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3431,3439, 2007 [source]