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1 Record 1 of 14 Zhang K; Chen HT; Chen X; Chen ZM; Cui ZC; Yang B Monodisperse silica-polymer core-shell microspheres via surface grafting and emulsion polymerization Source: MACROMOLECULAR MATERIALS AND ENGINEERING 2003, Vol 288, Iss 4, pp Full Paper: We describe a flexible method for preparing monodisperse silica-polystyrene core-shell microspheres. In this method, silica nanoparticles grafted with 3- (trimetfioxysilyl)propyl methacrylate (MPS) were employed as seeds in an emulsion polymerization. The thickness of the shells could be changed through varying the amount of the monomer. The monodispersity and diameters of the core-shell microspheres were found to depend on the size of the grafted silica nanoparticles and the concentration of emulsifier. In addition, we investigated the formation mechanism of the core-shell microspheres. Source item page count: 6 Publication Date: APR KR 29-char source abbrev: MACROMOL MATER ENG Record 2 of 14 Samanta D; Faure N; Rondelez F; Sarkar A Towards "designer" surfaces: functionalisation of self-assembled monolayer (SAM) on colloidal gold by alkene metathesis Source: CHEMICAL COMMUNICATIONS 2003, Iss 10, pp A variety of groups like a Fischer carbene complex, an N-hydroxysuccinimide or a ferrocene derivative have been grafted by ruthenium-catalyzed cross-metathesis reaction with terminal alkene groups on monolayer-protected gold clusters as a mild and convenient strategy to anchor functional molecules. Source item page count: 2 673FG 29-char source abbrev: CHEM COMMUN Page 1 of 9

2 Record 3 of 14 Raula J; Shan J; Nuopponen M; Niskanen A; Jiang H; Kauppinen EI; Tenhu H Synthesis of gold nanoparticles grafted with a thermoresponsive polymer by surface-induced reversible-addition-fragmentation chain-transfer polymerization Source: LANGMUIR 2003, Vol 19, Iss 8, pp This work focuses on the synthesis method of Au nanoparticles protected by a well-defined polymer monolayer. Nanosized, spherical gold clusters coated with poly(nisopropylacrylamide) (PNIPA) grafts were prepared by controlled radical polymerization. The polymerization of N-isopropylacrylamide was initiated from the surface of a gold nanoparticle modified with 4-cyanopentanoic acid dithiobenzoate for a reversible-additionfragmentation chain-transfer polymerization. The number mean diameter of the Au core was 3.2 nm as observed by high-resolution transmission electron microscopy. The molar mass of the PNIPA ligand was g/mol by gel permeation chromatography. The changes in the surface plasmon of gold were investigated in different media, and as functions of particle concentration, as well as of temperature in aqueous solutions. The particles were soluble at least slightly in water, forming aggregates. The area and the maximum wavelength of the plasmon band in water decreased with dilution and increasing temperature. During the collapse of PNIPA ligands the surroundings of the gold surface change from hydrophilic to hydrophobic. Source item page count: 6 Publication Date: APR CD Record 4 of 14 Kim JU; O'Shaughnessy B Morphology selection of nanoparticle dispersions by polymer media Source: PHYSICAL REVIEW LETTERS 2002, Vol 89, Iss 23, art. no Designable media can control properties of nanocomposite materials by spatially organizing nanoparticles. Here we theoretically study particle organization by ultrathin polymer films of grafted chains ("brushes"). Polymer-soluble nanoparticles smaller than a brush-determined threshold disperse in the film to a depth scaling inversely with particle volume. In the polymer-insoluble case, aggregation is directed: provided particles are nonwetting at the film surface, the brush stabilizes the dispersion and selects its final morphology of giant elongated aggregates with a brush-selected width. Source item page count: 4 Publication Date: DEC 2 617LG 29-char source abbrev: PHYS REV LETT Page 2 of 9

3 Record 5 of 14 Carrot G; Rutot-Houze D; Pottier A; Degee P; Hilborn J; Dubois P Surface-initiated ring-opening polymerization: A versatile method for nanoparticle ordering Source: MACROMOLECULES 2002, Vol 35, Iss 22, pp The coordination-insertion ring-opening polymerization of epsilon-caprolactone was initiated from amine or hydroxyl groups spread over the surface of silica (ca. 30 nm) or cadmium sulfide (ca. 1.5 nm) nanoparticles, respectively. The initiation selectively occurred from the surface functional groups after activation into aluminum alkoxides species. The covalent grafting of the polyester chains was confirmed by the solubilization of the nanoparticles in organic solvents, e.g., CHCl3 and THF for silica nanoparticles and toluene for CdS nanoparticles, at least when the surface-grrafted PCL chains were long enough. In the case of silica nanoparticles, the linear dependence of the PCL molar mass as determined by H-1 NMR analysis on the initial monomer-to-amine ratio confirmed the controlled character of the polymerization. Transmission electron microscopy of thin films of PCL-grafted CdS revealed an homogeneous dispersion of the semiconducting nanoparticles throughout the polyester matrix. Source item page count: 5 Publication Date: OCT MP 29-char source abbrev: MACROMOLECULES Record 6 of 14 Riley T; Stolnik S; Garnett MC; Illum L; Davis SS; Taylor P; Tadros TF Use of viscoelastic measurements for investigating interparticle interactions in dispersions of micellar-like poly(lactic acid)-poly(ethylene glycol) nanoparticles Source: LANGMUIR 2002, Vol 18, Iss 20, pp A series of poly(lactic acid)-poly(ethylene oxide) (PIA-PEG) AB block copolymers have been synthesized and used to produce aqueous dispersions of micellar-like nanoparticles. The hydrodynamic radius of the PLA core plus the stabilizing 5 kda PEG layer, as determined by photon correlation spectroscopy, increased with the molecular weight of the PIA block. PLA-PEG particles have possible application as drug carriers for targeted drug delivery. In addition to particle size, the layer thickness and mobility of the hydrated PEG chains will be important in determining the particle's ability to avoid uptake by the defense system of the body, the phagocytic cells of the reticuloendothelial system. Viscoelastic measurements were used to investigate interparticle interactions in concentrated dispersions of the PLA-PEG nanoparticles. This approach has not previously been used to study how the interactions in dispersions of micellar-like assemblies depend on the copolymer geometry. When the volume fraction of the dispersions, phi(core) was increased, the storage modulus, G', became greater than the loss modulus, G", indicating steric interaction between the PEG chains. At higher phi(core) values, compression of the grafted polymer chains was observed. The critical volume fraction at which overlap of the PEG chains commences, phi(core)(crit) (i.e., G' = G"), was used in conjunction with the overall hydrodynamic radius to determine the grafted PEG chain layer thickness. Micellar-like nanoparticles assembled from a PLA-PEG copolymer with a 5 kda PEG block and a relatively low molecular weight 3 kda PLA chain had an appreciable steric layer thickness of 6.3 nm. Hence, interparticle interactions in the concentrated dispersion were "soft" in nature as a result of the long-range interactions, as shown by the weak scaling dependence of the storage modulus on the volume fraction. The layer became more extended as the molecular weight of the PLA block was increased from 3 to 6 kda, and as a consequence the PEG chains became less compressible. By using this method to characterize the PEG layer, it should be possible to rationalize the in vivo Page 3 of 9

4 performance of the PLA-PEG nanoparticles and therefore aid the design of particulate drug carriers. Source item page count: 6 Publication Date: OCT 1 598WV Record 7 of 14 Rong MZ; Ji QL; Zhang MQ; Friedrich K Graft polymerization of vinyl monomers onto nanosized alumina particles Source: EUROPEAN POLYMER JOURNAL 2002, Vol 38, Iss 8, pp To enhance the interfacial interaction in alumina nanoparticles filled polymer composites, an effective surface modification method was developed by grafting polystyrene and polyacrylamide onto the particles. That is, the alumina surface was firstly treated with silane, followed by radical grafting polymerization in aqueous or non-aqueous systems. Results of infrared spectroscopy and dispersiveness in solvents demonstrated that the desired polymer chains have been covalently bonded to the surface of the alumina particles. They also greatly changed their surface characteristics. In addition, effects of polymerization conditions, including ways of monomer feeding, concentrations of monomer and initiator, and reaction time, on the grafting reaction were presented. It was found that the growing polymer radicals and/or the grafted polymer chains had a blocking effect on the diffusion of radicals or monomers towards the surface of nanoalumina. This was due to the fact that the interaction between the solvent and the grafted polymers was weaker than that between the grafted polymers and the nanoparticles. (C) 2002 Elsevier Science Ltd. All rights reserved. Source item page count: 10 Publication Date: AUG 560JA 29-char source abbrev: EUR POLYM J Page 4 of 9

5 Record 8 of 14 Mangeney C; Ferrage F; Aujard I; Marchi-Artzner V; Jullien L; Ouari O; Rekai ED; Laschewsky A; Vikholm I; Sadowski JW Synthesis and properties of water-soluble gold colloids covalently derivatized with neutral polymer monolayers Source: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2002, Vol 124, Iss 20, pp Citrate-capped gold nanoparticles as well as planar gold surfaces can be efficiently grafted with a covalently attached polymer monolayer a few nanometers thick, by simple contact of the metal surface with dilute aqueous solutions of hydrophilic polymers that are end-capped with disulfide moieties, as shown by UV/vis absorption, dynamic light scattering, and surface plasmon resonance studies. The hydrophilic polymer-coated gold colloids can be freeze-dried and stored as powders that can be subsequently dissolved to yield stable aqueous dispersions, even at very large concentrations. They allow for applying filtrations, gel permeation chromatography, or centrifugation. They do not suffer from undesirable nonspecific adsorption of proteins while allowing the diffusion of small species within the hydrogel surface coating. In addition, specific properties of the original hydrophilic polymers are retained such as a lower critical solution temperature. The latter feature could be useful to enhance optical responses of functionalized gold surfaces toward interaction with various substrates. Source item page count: 11 Publication Date: MAY YU 29-char source abbrev: J AM CHEM SOC Page 5 of 9

6 Record 9 of 14 Mori H; Seng DC; Zhang MF; Muller AHE Hybrid nanoparticles with hyperbranched polymer shells via self-condensing atom transfer radical polymerization from silica surfaces Source: LANGMUIR 2002, Vol 18, Iss 9, pp We present the synthesis of hyperbranched polymer-silica hybrid nanoparticles by selfcondensing vinyl polymerization (SCVP) via atom transfer radical polymerization (ATRP) from silica surfaces. ATRP initiators were covalently linked to the surface of silica particles, followed by SCVP of an initiator-monomer ("inimer") which has both a polymerizable acrylic group and an initiating group in the same molecule. Well-defined polymer chains were grown from the surface to yield hybrid nanoparticles comprised of silica cores and hyperbranched polymer shells having multifunctional bromoester end groups, as confirmed by elemental analyses and Fourier transform infrared measurements. Characterization of soluble polymers obtained in solution by gel permeation chromatography (GPC), GPC/ viscosity, and NMR suggests the formation of highly branched polymers, Correlation of molecular parameters of the soluble polymers with the polymers grafted on the surface is discussed in view of theoretical considerations. Hydrolysis of the ester functionality of branched poly(tert-butyl acrylate), which was obtained by copolymerization of the inimer and tert-butyl acrylate, created branched poly(acrylic acid)-silica hybrid nanoparticles. The hybrid nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, scanning force microscopy, and dynamic light scattering. Source item page count: 12 Publication Date: APR TF Page 6 of 9

7 Record 10 of 14 Zhou QY; Wang SX; Fan XW; Advincula R; Mays J Living anionic surface-initiated polymerization (LASIP) of a polymer on silica nanoparticles Source: LANGMUIR 2002, Vol 18, Iss 8, pp To demonstrate living anionic surface-initiated polymerization (LASIP) on silica nanoparticles, the initiator precursor 1,1-diphenylethylene (DPE) was functionalized with alkyldimethylchlorosilane and grafted onto silica particle surfaces. n-buli was used to activate the DPE, which allowed the anionic polymerization of the styrene monomer to proceed in benzene solution. A high-vacuum reactor was used to allow polymerization from the surface of silica particles under anhydrous solution conditions. The dispersion of the DPE functionalized silica particles showed a distinct red color indicating an activated nanoparticle- DPE-n-BuLi complex suitable for anionic polymerization. The degree and mechanism of polymerization were determined based on characterization of the grafted and detached polystyrene chains using thermogravimetric analysis, size exclusion chromatography, NMR, and Fourier transform infrared spectroscopy. In addition, atomic force microscopy and X-ray photoelectron spectroscopy were used to characterize the polymer-coated nanoparticles. The importance of activation of the grafted initiator, control of aggregation, and removal of the excess n-buli for high molecular weight formation is emphasized. While the polydispersities are broader compared to those obtained by solution polymerization of a free initiator, a living anionic polymerization mechanism is still observed. Source item page count: 8 Publication Date: APR GZ Page 7 of 9

8 Record 11 of 14 Roan JR; Kawakatsu T Self-consistent-field theory for interacting polymeric assemblies. II. Steric stabilization of colloidal particles Source: JOURNAL OF CHEMICAL PHYSICS 2002, Vol 116, Iss 16, pp The self-consistent-field (SCF) theory developed in Part I [J. Chem. Phys. 116, 7283 (2002), preceding paper] is employed to compute the interaction between particles coated by endgrafted homopolymers in good solvent, where the particles and the homopolymers have comparable sizes. The result shows that, contrary to the prediction of the conventional theory for colloidal stabilization and previous SCF studies, the interaction is attractive, repulsive, and attractive at large, intermediate, and small distances, respectively, for densely grafted particles, while it is purely attractive for sparsely grafted particles. The attractive interaction is a consequence of two important factors that were ignored in previous studies: (i) the spheresphere geometry of the system and (ii) the segment density associated with individual particle being deformed anisotropically, with respect to the particle, under the perturbation of other particles. We argue that the conventional wisdom that end-grafted homopolymers in good solvent always impart stability indeed is correct only in a kinetic sense and that our result will become more observable in systems composed of nanoparticles. Limitations of our prediction and considerations that must be carefully taken into account when generalizing our result to micron-sized particles and star polymers are discussed. (C) 2002 American Institute of Physics. Source item page count: 16 Publication Date: APR FB 29-char source abbrev: J CHEM PHYS Record 12 of 14 Liu Z; Pappacena K; Cerise J; Kim J; Durning CJ; O'Shaughnessy B; Levicky R Organization of nanoparticles on soft polymer surfaces Source: NANO LETTERS 2002, Vol 2, Iss 3, pp We investigate the organization of gold nanocrystals on thin, fluid films consisting of polymer chains tethered by one end to an underlying substrate in a polymer brush configuration. The thickness of the polymer brush is comparable to the nanocrystal size. Thinner polymer brushes are found to suppress aggregation of the nanoparticles, leading to stable, elongated particle-rich domains, The results suggest new approaches for modification of macroscopic surfaces with nanoscopic particles. Source item page count: 6 Publication Date: MAR 535JF 29-char source abbrev: NANO LETTERS Page 8 of 9

9 Record 13 of 14 Roan JR Attraction between nanoparticles induced by end-grafted homopolymers in good solvent Source: PHYSICAL REVIEW LETTERS 2001, Vol 86, Iss 6, pp The interactions between nanoparticles coated by end-grafted homopolymers of comparable size are studied using Edwards' self-consistent field (SCF) theory. The equilibrium monomer density distribution is obtained by solving the SCF equations in bispherical coordinates. It is shown that, because of the spherical geometry and redistribution of monomer density, endgrafted homopolymers in good solvent environment can induce attractive interactions. This result suggests that steric stabilization of nanoparticles requires new working principles and that the equilibrium distance between nanopnrticles may be tuned by end-grafted polymers. Source item page count: 4 Publication Date: FEB 5 398XD 29-char source abbrev: PHYS REV LETT Record 14 of 14 Loppinet B; Sigel R; Larsen A; Fytas G; Vlassopoulos D; Liu G Structure and dynamics in dense suspensions of micellar nanocolloids Source: LANGMUIR 2000, Vol 16, Iss 16, pp We present an experimental description of the dynamics of a dense colloidal suspension of model hairy nanoparticles using dynamic light scattering. These colloids were obtained by cross-linking the poly(2-cinnamoylethyl methacrylate) cores of polystyrene-block-poly(2- cinnamoylethyl methacrylate), copolymer micelles. Because of their small size and the small spacing of their liquidlike structure, as detected with small-angle neutron scattering, these particles enable the systematic investigation of the low-scattering wavevector (q) fraction of the dynamic structure factor (S(q,t)) away from the peak, which relates to the osmotic modulus of the suspension. The two relaxation processes contributing to S(q,t) are the fast cooperative diffusion of the concentration fluctuations (hair interactions) and the selfdiffusion of the slightly polydisperse cores (incoherent contribution). The former speeds up and loses intensity with increasing concentration, analogous to linear and hyperstar polymer solutions, whereas the latter slows down and exhibits virtually increasing intensity with concentration as a consequence of the correlation hole at low q's, much like the hard sphere colloids. The study of these hairy particles contributes to the overall picture of the dynamic response of concentrated colloidal suspensions sterically stabilized by grafted macromolecules. Source item page count: 5 Publication Date: AUG 8 341MG Acceptable Use Policy Copyright 2003 Thomson ISI Page 9 of 9