Triethoxysilane

Abstract: Stable dispersions of monodisperse colloidal silica spheres containing a dye or fluorophore have been synthesized according to a general procedure and dispersed in polar and apolar liquids. The procedure consists of the coupling of the dye to a silane coupling agent, (3++minopropyl)triethoxysilane, and the controllable incorporation of the reaction product into the silica sphere. The silica spheres are prepared from tetraethoxysilane in mixtures of ammonia, water, and ethanol. The composition of the silica spheres can be controlled in such a way that the organic groups can be placed on the surface, in a thin shell inside the particle or distributed through the volume of an inner core. Fluorescein isothiocyanate was used to make easily bleachable, fluorescent silica spheres. Hydrophilic charge stabilized and organophilic sterically stabilized 1-octadecanol-coated dyed silica systems were synthesized and dispersed in several solvents. All the particles were characterized after the several reaction steps by static and dynamic light scattering and transmission electron microscopy. The fluorescent spheres were further characterized by fluorescence spectroscopy and confocal scanning laser fluorescence microscopy. Great effort was taken to prepare monodisperse dispersions free of clusters of particles. Such model dispersions are required for (scattering) studies of interparticle interactions in (concentrated) systems. Therefore, the several steps of the synthesis and optical characterization are described in detail.

Abstract: The amine moiety is an important functionality for many applications such as enzyme immobilization on porous solid supports. In this study, mesoporous SBA-15 was functionalized by co-condensation of tetraethoxysilane (TEOS) with organosilane (aminopropyl)triethoxysilane (APTES) in a wide range of molar ratios of APTES:TEOS in the presence of triblock copolymer P123 under acidic synthetic conditions. The functionalized materials were characterized by physical adsorption, CHN elemental analysis, and various spectroscopic techniques. The data of FTIR, elemental analysis, XPS, and solid-state NMR demonstrated the incorporation of amine functional groups on the surface and inside the pore walls of the APTES-functionalized SBA-15 samples. The results of SAXS, N2 adsorption, and TEM showed the effect of APTES present in the initial synthesis mixtures on the formation of SBA-15 mesostructure such as structural ordering, pore size, and surface area. Reasons behind the observed strong adverse effect of APTES on SBA...

Abstract: Monodisperse silica particles (SiPs) of diameter between 100 and 1500 nm were surface-modified in a mixture of ethanol/water/ammonia with a newly designed triethoxysilane having an atom transfer radical polymerization (ATRP) initiating site, (2-bromo-2-methyl)propionyloxyhexyltriethoxysilane. The surface-initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator-fixed SiPs in the presence of a “sacrificial” (free) initiator. The polymerization proceeded in a living manner in all examined cases, producing SiPs coated with well-defined PMMA of a target molecular weight up to 480K with a graft density as high as 0.65 chains/nm2. These hybrid particles had an exceptionally good dispersibility in organic solvents. Transmission electron microscopic and atomic force microscopic observations of their monolayers prepared at the air−water interface revealed that they formed an ordered 2-dimensional lattice extending throughout the monolayer.