Routes to monodispersivity

Recent scientific literature demonstrates a growing interest in new methods of nanoparticle synthesis, driven primarily by an ever-increasing awareness of the unique properties and technological importance of nanostructured materials. The fabrication of nanoparticles within reverse microemulsions [40, 146] has been shown to be a convenient route to monodisperse particles of controllable size. A recognised goal of these synthetic approaches is to achieve control over the composition, size, surface species, solubility, stability, isolability and other functional properties of the nanostructures. The combination of reverse microemulsion and microwave heating has the added advantage that the oil phase in the reverse microemulsion system is transparent to microwave so that the aqueous domains are heated directly, selectively and rapidly. 

P. Garstecki, H.A. Stone, and G.M. Whitesides, Mechanism for flow-rate controlled breakup in cortfined geometries A route to monodisperse emulsions, Physical Review Letters, 94, (2005). 

It has been reported that living radical polymerization of 4-acetoxystyrene with a TEMPO (2,2,6,6-tetramethylpiperidine-l-oxyl) adduct as the initiator, followed by base hydrolysis produces PHOSTs with narrow polydispersity, 1.1-1.4, which tend to have a 10-20°C higher 7g than their conventional PHOST counterparts (with polydispersity of 2.0-2.4), whose 7g ranges from 140 to 180°C. Hirao et al. have demonstrated the synthetic route to monodisperse PHOST, involving the living anionic polymerization of 4-tert-butyl(dimethyl)siloxystyrene... 

Routes to Monodispersivity Large Molecules or Clusters. True monodispersivity may be obtained with mass spectrometric separation. Although only microscopic samples are likely to be prepared by this approach, a program at Cavendish Laboratory in Cambridge, England is examining this method to prepare clusters with a monodispersivity of one part in 500. 

Routes to Monodispersivity Small Crystallites. Spin-coating methods containing precursor salts can produce very small crystallites on the surface of a silicon wafer (63-W). Compounds of copper nitrate, for example, have been readily... 

Electrochemistry provides routes to directly prepare nanostructures both delocalized in a random or organized way and localized at predefined surface sites with adjustable aspect ratios. Purity, monodispersity, ligation, and other chemical properties and treatments are definitely important in most cases. By delocalized electrodeposition it is possible to decorate large areas of metal or semiconductor surfaces with structures of a narrow size distribution stable nuclei-clusters can be... 

The reverse ME technique provides an easy route to obtain monodispersed metal nanoparticles of the defined size. To prepare supported catalyst, metal nanoparticles are first purified from the ME components (liquid phase and excess of surfactant) while retaining their size and monodispersity and then deposited on a structured support. Due to the size control, the synthesized material exhibits high catalytic activity and selectivity in alkyne hydrogenation. Structured support allows suitable catalyst handling and reuse. The method of the catalyst preparation is not difficult and is recommended for the... 

P. Perrin Amphiphilic Copolymers A New Route to Prepare Ordered Monodisperse Emulsions. Langmuir 14, 5977 (1998). 

Y. Yin, Y. Lu, B. Gates, and Y. Xia Template-Assisted Self Assembly A Practical Route to Complex Aggregates of Monodispersed Colloids with Well-Defined Sizes, Shapes and Structures. J. Am. Chem. Soc. 123, 8718 (2001). 

Owing to the simphcity and versatility of surface-initiated ATRP, the above-mentioned AuNP work may be extended to other particles for their two- or three-dimensionally ordered assemblies with a wide controllabiUty of lattice parameters. In fact, a dispersion of monodisperse SiPs coated with high-density PMMA brushes showed an iridescent color, in organic solvents (e.g., toluene), suggesting the formation of a colloidal crystal [108]. To clarify this phenomenon, the direct observation of the concentrated dispersion of a rhodamine-labeled SiP coated with a high-density polymer brush was carried out by confocal laser scanning microscopy. As shown in Fig. 23, the experiment revealed that the hybrid particles formed a wide range of three-dimensional array with a periodic structure. This will open up a new route to the fabrication of colloidal crystals. 

Summary A synthetic route to highly fluorescent organic semiconductors with rigid connections to curable alkoxysilanes is described. The title compounds are prepared via Heck reactions of monodisperse bromo-OPVs with allyl-alkoxysilanes. A combined extension of the Jt-system and coimection with alkoxysilanes is possible when an alkoxysilyl-styrene is used as a substrate. Hydrolysis and condensation of alkoxysilanes yields linear and cyclic oligo-OPV-siloxanes or three-dimensional networks, thus allowing the transformation of small molecules into luminescent materials with well-defined chromophores. 

We have recently developed a novel synthetic route to produce a series of monodispersed Pd/Ni nanoparticles of similar size by using a successive reduction technique [124]. Nickel atoms were deposited on 2.5-nm Pd nanoparticles corresponding to the magic number of 561 atoms with a 5-shell structure [66] at various Ni/Pd molar ratios (1/561, 2/561, 10/561, 15/561, 38/561, 168/561, 281/561,... 

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