An efficient and rapid method for the synthesis of 3,4,5-substituted furan-2 (5H)-ones has been achieved through a three-component reaction of aniline, dialkyl acetylenedicarboxylate, and aromatic aldehydes using nano-colloidal silica-tethered polyhedral oligomeric silsesquioxanes with eight branches of 3-aminopropyltriethoxysilane (nano-colloidal silica @APTPOSS) as a superior catalyst under m...

Flame aerosol technology is a versatile method for scalable synthesis of nanoparticles. Since particles are produced and collected in a dry state, dispersibility and further functionalization could pose hurdles to their biomedical use. We report on a one-pot, scalable and robust procedure for the PEGylation of flame-made yttria and silica nanoparticles. We demonstrate improved colloidal stabili...

We investigate the structure and flow behavior of colloidal gels in microchannels using confocal microscopy. Silica particles are first coated with a cationic polyelectrolyte and then flocculated by the addition of an anionic polyelectrolyte. In the quiescent state, the suspension is an isotropic and homogeneous gel. Under shear flow, the suspension contains dense clusters that yield at intercl...

The effects of the addition of submicrometer-sized colloidal silica spheres on the linear and nonlinear rheology of semidilute solutions of a viscoelastic gel are studied. For a 1.4 wt% solution of the surfactant CTAT, a peak in the zero-shear rate viscosity eta(0) is observed at approximately equal weight percents of silica and CTAT. This peak shifts to lower silica concentrations on increasin...

Silica sol, i.e., colloidal SiO2, may be used as a low-pH injection grout for very fine fractures in the construction of deep geological repositories for radioactive waste in Sweden and in Finland. If the bentonite barrier encounters SiO2-colloid particles under conditions favorable for aggregation, there is concern that it will modify the bentonite barrier at the bentonite/bedrock interface. I...

Quartz surfaces and colloidal silica particles were derivatized with a poly(methyl methacrylate) copolymer containing spirobenzopyran (SP) photochromic molecules in the pendant groups at a concentration of 20 mol %. Two-photon near-IR excitation (approximately 780 nm) was then used to create chemically distinct patterns on the modified surfaces through a photochromic process of SP transformatio...

an epoxy resin was modified by silica nanoparticles and cured with an anhydride. the particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. electron microscopy images showed that the silica particles were well dispersed throughout the resin. tensile test results showed that young’s modulus and tensile strength increased with the vo...

in this paper the influence of two different sizes of silica particles (micro-silica and nano-silica) was studied on mechanical properties of sulfur and sulfur composite. to improve the structural properties, sulfur was plasticized using dicyclopentadiene (dcpd) and methyl styrene (mst). plasticized sulfur composite was prepared by melt blending of plasticized sulfur and silica particles. the i...

Well-defined polymer brushes grafted onto silica nanoparticles were prepared by reversible additionfragmentation chain transfer polymerization (RAFT). A versatile RAFT agent, 4-cyanopentanoic acid dithiobenzoate (CPDB), was attached to amino-functionalized colloidal silica nanoparticles by direct condensation of the mercaptothiazoline-activated CPDB with the surface amino groups. RAFT polymeriz...

The colloidal stability, phase behavior, and solubility of silica nanoparticles (3-10 nm) that are formed in basic solutions of monovalent cations (primarily tetrapropylammonium) are investigated using a combination of chemical equilibria and electrostatic models. The free-energy gain associated with the formation of an electric double layer surrounding the nanoparticle was obtained by solving ...