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Diameter Smaller (diameter + smaller)
Selected AbstractsThe production of high polymer to surfactant microlatexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Raul P. Moraes Abstract Starved-feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1-pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48,54, 2010 [source] Nanocellular Foams of PS/PMMA Polymer BlendsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 1 2008Tetsuo Otsuka Abstract A nanocellular PS/PMMA polymer blend foam was prepared, where bubble nucleation was localized in the PMMA domains. The blend, which contains dispersed nanoscale PMMA islands, was prepared by polymerizing MMA monomers in a PS matrix to form highly dispersed PMMA domains in the PS matrix by diffusion mixing. The resulting blend was foamed with CO2 at room temperature. A higher depressurization rate at lower foaming temperature made the bubble diameter smaller and the bubble density larger, and a higher PS composition in the blend resulted in a larger bubble density. A void with 40,50 nm in average diameter and a pore density of 8.5,×,1014 cm,3 was obtained as for the finest nanocellular foams. [source] 1H MRS studies of signals from mobile lipids and from lipid metabolites: comparison of the behavior in cultured tumor cells and in spheroidsNMR IN BIOMEDICINE, Issue 2 2004Antonella Rosi Abstract 1H magnetic resonance studies on MCF-7 and HeLa cells were undertaken to reveal differences in lipid and lipid metabolite signals during the growth in culture. High intensity mobile lipid (ML) signals were found during the first days in culture, while afterwards the same signals declined and started increasing again at confluence and at late confluence. At the same time, signals from the lipid metabolite phosphocholine decreased in intensity while signals from glycerophosphocholine in MCF-7 and from choline in HeLa increased as cells approached confluence. Spectral parameters from actively proliferating and non-proliferating cells were used to classify cells with respect to the proliferative conditions by means of a multivariate statistical analysis. Furthermore, it was shown that polyunsaturation of mobile lipid chains was lower in the confluent group with respect to the actively proliferating cells. The examination of spectra from suspensions of MCF-7 spheroids with diameter smaller than 500,,m suggests that cells in spheroids are in condition of lipid metabolism similar to that of confluent cultured cells. Copyright © 2004 John Wiley & Sons, Ltd. [source] Preparation of Uniform, Water-Soluble, and Multifunctional Nanocomposites with Tunable SizesADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Dechao Niu Abstract Novel, thiol-functionalized, and superparamagnetic, silica composite nanospheres (SH-SSCNs) with diameters smaller than 100,nm are successfully fabricated through the self-assembly of Fe3O4 nanoparticles and polystyrene100 - block -poly(acrylic acid)16 and a subsequent sol-gel process. The size and magnetic properties of the SH-SSCNs can be easily tuned by simply varying the initial concentrations of the magnetite nanoparticles in the oil phase. By incorporating fluorescent dye molecules into the silica network, the composite nanospheres can be further fluorescent-functionalized. The toxicity of the SH-SSCNs is evaluated by choosing three typical cell lines (HUVEC, RAW264.7, and A549) as model cells, and no toxic effects are observed. It is also demonstrated that SH-SSCNs can be used as a new class of magnetic resonance imaging (MRI) probes, having a remarkably high spin,spin (T2) relaxivity (r2*,=,176.1,mM,1 S,1). The combination of the sub-100-nm particle size, monodispersity in aqueous solution, superparamagnetism, and fluorescent properties of the SH-SSCNs, as well as the non-cytotoxicity in vitro, provides a novel and potential candidate for an earlier MRI diagnostic method of cancer. [source] | ||||||||||