Copper nanoparticles are being given considerable attention as of late due to their interesting properties and potential applications in many areas of industry. One such exploitable use is as the major constituent of conductive inks and pastes used for printing various electronic components. In this study, copper nanoparticles were synthesized through a relatively large-scale (5 l), high-throughput (0.2 M) process. This facile method occurs through the chemical reduction of copper sulfate with sodium hypophosphite in ethylene glycol within the presence of a polymer surfactant (PVP), which was included to prevent aggregation and give dispersion stability to the resulting colloidal nanoparticles. Reaction yields were determined to be quantitative while particle dispersion yields were between 68 and 73%. The size of the copper nanoparticles could be controlled between 30 and 65 nm by varying the reaction time, reaction temperature, and relative ratio of copper sulfate to the surfactant. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) images of the particles revealed a spherical shape within the reported size regime, and x-ray analysis confirmed the formation of face-centered cubic (FCC) metallic copper. Furthermore, inkjet printing nanocopper inks prepared from the polymer-stabilized copper nanoparticles onto polyimide substrates resulted in metallic copper traces with low electrical resistivities (≥3.6 µΩ cm, or ≥2.2 times the resistivity of bulk copper) after a relatively low-temperature sintering process (200 °C for up to 60 min).

Monolayer-protected silver nanoparticles were directly synthesized in a highly concentrated organic phase (>2 M) and then printed into conductive lines on polyimide by a drop-on-demand inkjet printer. The fully organic phase system contains silver nitrate as a silver precursor, n-butylamine as a media dissolving silver salt, dodecanoic acid as a capping molecule, toluene as a solvent, and sodium borohydride as a reducing reagent. Even using only generic chemicals, monodispersed silver nanocrystals with size of 7 nm were easily synthesized at the 100 g scale in a 1 litre reactor. Hydrocarbon monolayer-protected silver nanocrystal showed excellent dispersion stability even at metal content >70 wt%. The silver ink with metal content of 33 wt% had a viscosity of 5.4 cP and surface tension of 25 dyn cm −1 . The silver ink was successfully inkjetted on variable substrates and then metallized at 250 • C. The metallized silver patterns exhibited very low specific electrical resistance (6 µ cm)

ThecommercialpolyimideMatrimidwasmodifiedbybrominationforthe purposeofimprovingitsmembrane-transportpropertiesasagas-separationmaterial andprovidingfunctionalgroupreactivityforfurthermodifications.Theunmodifiedand brominatedpolymerswerecharacterizedbyelementalanalysisandone-dimensional andtwo-dimensionalNMR,whichrevealedthatonebromineatomperrepeatunitwas incorporatedregioselectivelyontotheindanearomaticring.Thethermalandphysical propertiesofthepolymersbeforeandafterbrominationwerealsoinvestigated.The gas-transportpropertiesoftheunmodifiedandbrominatedpolymerswerecompared.

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A series of modified polymers with 4-trimethylsilyl-R-hydroxylbenzyl (HBTMS) substituents were made as new materials for membrane gas separation. HBTMS was introduced onto polysulfone (PSf), tetramethylpolysulfone (TMPSf), and hexafluoropolysulfone (6FPSf) by forming lithiated polymer intermediates followed by treatment with an electrophile, p-trimethylsilylbenzaldehyde. The resulting side substituent contains the bulky trimethylsilyl (TMS) groups separated from the polymer chain by an aromatic ring. The polymer structures were characterized by NMR spectroscopy, and thermal properties were investigated by differential scanning calorimetry and thermogravimetry. The permeability coefficients of the resulting polymers PSf-HBTMS, TMPSf-HBTMS, and 6FPSf-HBTMS showed considerable increases over the unmodified polymers. TMPSf-HBTMS showed the greatest improvements in gas transport properties with large increases in both CO 2 and O2 permeabilities of ∼3-fold (72 and 18 Barrers, respectively) compared with TMPSf. In the case of the CO2/N2 gas pair, there was an absence of the typical accompanying tradeoff shown by decreases in permselectivity with increasing permeability. Comparisons of this series of polymers containing the new HBTMS substituent were made with those having other TMS pendant groups.

In this study, we attempted to synthesize organic-soluble silver nanoparticles in the concentrated organic phase with an environmentally friendly method. The fully organic phase system contains silver acetate as a silver precursor, oleic acid as both a medium and a capping molecule, and tin acetate as a reducing agent. Monodisperse silver nanoparticles with average diameters of ca. 5 nm can be easily synthesized at large scale. Only a small usage of tin acetate (<0.05 eq.mol) resulted in a high synthesis yield (>90%). Also, it was investigated that the residual tin atom does not exist in the synthesized silver nanoparticles. This implied that tin acetate acts as a reducing catalyst.

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/npsi/ctrl?action=rtdoc&an=8906267&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=8906267&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1021/ma035739i Macromolecules, 37, 4, pp. 1403Macromolecules, 37, 4, pp. -1410Macromolecules, 37, 4, pp. , 2004 Preparation and characterization of polysulfones containing both hexafluoroisopropylidene and trimethylsilyl groups as gas separation membrane materials Dai, Y.; Guiver, Michael; Robertson, Gilles; Kang, Y.; Lee, Kunchan; Jho, J. Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Korea; and Hyperstructured Organic Materials Research Center and School of Chemical Engineering, Seoul National University, Seoul 151-744, Korea Received November 19, 2003; Revised Manuscript Received December 16, 2003 ABSTRACT: Trimethylsilylated derivatives of hexafluoropolysulfone (6FPSf) and tetramethylhexafluoropolysulfone (TM6FPSf) were prepared by reaction of lithiated polymer intermediates with halotrimethylsilane electrophiles for a membrane gas separation study to compare improvements in gas permeabilities with those of unmodified polymers. Ortho sulfone substituted 6FPSf and TM6FPSf having pendant trimethylsilyl (TMS) groups were obtained by a two-step process involving first direct lithiation of 6FPSf and TM6FPSf solutions with n-butyllithium to afford ortho sulfone dilithiated intermediates, followed by reaction with a TMS electrophile. The corresponding ortho ether 6FPSf derivative was obtained by lithiation of dibrominated 6FPSf at the bromine sites, followed by reaction with a TMS electrophile. The degree of substitution (DS) of the TMS groups was g2.0 and was dependent on the molar ratio of n-butyllithium and electrophile quantity, electrophile reactivity, and reaction conditions. Detailed structural characterization and DS of the modified polymers were obtained by nuclear magnetic resonance spectroscopy. The glass transition temperatures and thermal stabilities were determined by differential scanning calorimetry and thermogravimetric analysis, respectively. Polymer chain d-spacing was investigated using wide-angle X-ray diffraction. Polymer free volume was calculated from the polymer density and specific van der Waals volume. The polymer gas permeability coefficients (P) were measured for He, CO 2,O 2, and N2. Both CO2 and O2 permeabilities of modified 6FPSf increased by 8-9-fold (P(CO2) ) 110 barre...