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Hybrid Nanocomposites (hybrid + nanocomposite)
Selected AbstractsPEGylated Calcium Phosphate Nanocomposites as Smart Environment-Sensitive Carriers for siRNA DeliveryADVANCED MATERIALS, Issue 34 2009Mingzhen Zhang A novel inorganic,organic hybrid nanocomposite is formed in situ using a simple and straightforward method. Conjugate of short interfering RNA (siRNA) duplex with poly(ethylene glycol) via a disulfide linkage (PEG,SS,siRNA) is demonstrated to regulate the crystal growth of calcium phosphate (CaP), yielding a monodispersed nanocomposite. The resultant nanocomposite can be utilized as nanocarriers for siRNA delivery. [source] X-ray powder diffraction quantitative analysis of an amorphous SiO2,poly(methyl methacrylate) nanocompositeJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2008P. Riello Quantification of individual phases within a multiphase amorphous material has been achieved using a newly developed technique based on X-ray powder diffraction. The quantification method was developed during a study of an amorphous silica,poly(methyl methacrylate) (SiO2,PMMA) hybrid nanocomposite. The efficiency of the method as a quantifying tool for individual phases was demonstrated for samples of SiO2,PMMA prepared either by polymerization of methyl methacrylate in the presence of amorphous SiO2 or by mechanically mixing known quantities of the individual and pre-prepared SiO2 and PMMA materials. The weight percentages of amorphous SiO2 in the nanocomposites as determined by application of the new technique were analogously found to be 29%, a result that was supported by thermogravimetric analysis and helium picnometry measurements. [source] Polyhedral Oligomeric Silsesquioxane (POSS) Nanoscale Reinforcement of Thermosetting Resin from Benzoxazine and BisoxazolineMACROMOLECULAR RAPID COMMUNICATIONS, Issue 23 2005Qiao Chen Abstract Summary: The reaction between octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) and 2,2,-(1,3-phenylene)-bis(4,5-dihydro-oxazoles) (PBO) over different temperature ranges was confirmed by FT-IR spectroscopy. The OAPS was used to modify benzoxazine (BZ) in the presence of PBO. The novel polybenzoxazine (PBZ)-PBO/OAPS hybrid nanocomposite was prepared by solvent methods. Dynamic mechanical analyses indicated that the nanocomposites exhibited much higher Tg values than the pristine PBZ and PBZ-PBO resin, and the storage modulus of the nanocomposites was maintained at higher temperatures, although only a small amount of OAPS was incorporated into the systems. Dynamic thermogravimetric analysis showed that the thermal stability of the hybrid was also improved by the inclusion of OAPS. DMA of PBZ (a), PBZ-PBO (b), and PBZ-PBO/OAPS nanocomposites (c,e). [source] Ultrasonochemical-assisted fabrication and evaporation- induced self-assembly (EISA) of POSS-SiO2@Ag core/ABA triblock copolymer nanocomposite filmPOLYMER COMPOSITES, Issue 9 2010Murugan Veerapandian Poly(ethylene glycol)-octafunctionalized polyhedral oligomeric silsesquioxane (POSS) (Mn = 5576.6 g/mol) alloying agent stabilized amphiphilic silica@silver metalloid nanocomposite blended with a triblock copolymer poly(p -dioxanone- co -caprolactone)- block -poly(ethylene oxide)- block -poly(p -dioxanone- co -caprolactone) (POSS-SiO2@Ag/PPDO- co -PCL- b -PEG- b -PPDO- co -PCL) has been synthesized in both water and in organic medium utilizing ultrasonochemical reaction. The POSS stabilized pre-made metalloid was successfully dispersed in amphiphilic PPDO- co -PCL- b -PEG- b -PPDO- co -PCL (ABA) triblock copolymer matrix of molecular weight 45.9 × 104 g/mol. The mechanism of synthesis of high concentration of SiO2@Ag nanocomposite from TEOS/AgNO3 (in the presence of NH4OH as catalyst/NaBH4 as reductant) nonmetal/metal precursors and the successful EISA of POSS-SiO2@Ag/ABA nanocomposite into films has been discussed. The successful synthesis of metalloid nanocomposite was morphologically accessed by field emission-scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Surface plasmon resonance was ensured from UV,visible spectral analysis. Identity and the crystallinity of as prepared nanocomposite were studied by X-ray diffractometer. Structural and luminescence properties of the nanocomposite were examined by Fourier transform infrared spectroscopy and photoluminescence. Thermogravimetric analysis was carried out to study the thermal stability of the resulting hybrid nanocomposite. The resultant inorganic,organic nanocomposite can be easily suspended in water and would be useful in variety of applications. POLYM. COMPOS., 31:1620,1627, 2010. © 2009 Society of Plastics Engineers [source] Templated Synthesis of Mesoporous Superparamagnetic Polymers,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2007B. Fuertes Abstract We present a novel synthetic strategy for fabricating superparamagnetic nanoparticles randomly dispersed in a mesoporous polymeric matrix. This method is based on the use of mesoporous silica materials as templates. The procedure used to obtain these mesoporous magnetic polymers consisted in: a),generating iron oxide ferrite magnetic nanoparticles (FMNP) of size ,,7,8,nm within the pores of the silica, b),loading the porosity of the silica/FMNP composite with a polymer (Polydivinylbenzene), c),selectively removing the silica framework from the resulting silica/FMNP/polymer composite. Such magnetic porous polymeric materials exhibit large surface areas (up to 630,m2,g,1), high pore volumes (up to 0.73,cm3,g,1) and a porosity made up of mesopores. In this way, it is possible to obtain superparamagnetic mesoporous hybrid nanocomposites that are easily manipulated by an external magnetic field and display different magnetic behaviours depending on the textural properties of the template employed. [source] Aqueous Stabilization and Self-Assembly of Graphene Sheets into Layered Bio-Nanocomposites using DNAADVANCED MATERIALS, Issue 31 2009Avinash J. Patil Stabilization of aqueous suspensions of graphene single sheets by single-stranded DNA is demonstrated using a range of physical methods. The negatively charged bio-functionalized graphene sheets are spontaneously assembled into layered hybrid nanocomposites containing intercalated DNA molecules, or co-intercalated mixtures of DNA and the redox protein, cytochrome c. Small-molecule reducing agents readily access the intercalated proteins. [source] Synthesis and characterization of hybrid nanocomposites comprising poly(vinyl alcohol) and colloidal silicaADVANCES IN POLYMER TECHNOLOGY, Issue 3 2008Mousumi De Sarkar Abstract Organic,inorganic hybrid composite films were developed using poly(vinyl alcohol) (PVA) and an aqueous dispersion of colloidal silica of initial particle size of 15,30 nm. The hybrid films, prepared with varied proportion of colloidal silica (10,90 phr), were found to be transparent, indicating the nanolevel dispersion of the inorganic component over the polymer. Morphological studies further revealed no significant agglomeration of the silica domains embedded into the polymer matrix. A depression in glass transition temperature of PVA is observed with increasing proportion of silica. The degree of crystallinity also showed a decreasing trend with increasing amount of silica. However, the composite films demonstrated superior mechanical performances, higher resistances to dissolution in boiling water, and lower permeability compared with virgin PVA, owing to the better interaction between PVA and silica as well as the reinforcing action of nanosilica particles in the polymer matrix. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:152,162, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20129 [source] Ternary magnetic nanocomposites based on core,shell Fe3O4/polyaniline nanoparticles distributed in PVDF matrixPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2010Mykhaylo Petrychuk Abstract Magnetic, electric, and radioprotector properties of hybrid nanocomposites of Fe3O4 nanoparticles with and without a shell of polyaniline (PANI), which is doped with dodecylbenzenesulfonic acid (DBSA), dispersed in polyvinylidene fluoride (PVDF) matrix have been studied. It has been found that the presence of PANI,DBSA as a separate filler in the ternary nanocomposite film, which also contains as another filler the core,shell Fe3O4/PANI,DBSA nanoparticles, facilitates dispersion of the magnetic filler due to the improvement of its compatibility with the PVDF matrix. This leads both to the decrease in coefficient of squareness of the hysteresis loop and to the increase in electromagnetic energy (EME) absorption of the nanocomposite film. [source] Completely discontinuous organic/ inorganic hybrid nanocomposites by self-curing of nanobuilding blocks constructed from reactions of [HMe2SiOSiO1.5]8 with vinylcyclohexenePOLYMER INTERNATIONAL, Issue 11 2007Norihiro Takamura Abstract The reaction of 4-vinyl-1-cylcohexene with [HMe2SiOSiO1.5]8 provides tetra- and octa-2-cyclohexenylethyloctasilsesquioxanes. The tetrabifunctional [cyclohexenylethylMe2SiOSiO1.5]4 -[HMe2SiOSiO1.5]4 (average degree of functionalization) melts near 80 °C and can be cast and then cured (by thermal hydrosilylation) into transparent nanocomposite shapes. These materials, while not nanoporous, offer dielectric constants of 2.8,2.9 at 100 kHz to 3 MHz, and are air stable to temperatures , 400 °C. The resulting materials appear (by X-ray diffraction) to be partially ordered after curing. The octafunctional material also melts at low temperatures (ca 120 °C) and can be copolymerized with hydridosiloxanes to give similar materials with lower thermal stability. The synthesis and characterization of the starting materials is described, as well as thermal curing studies and properties characterization of the resultant nanocomposites. Copyright © 2007 Society of Chemical Industry [source] Use of recombinant rotavirus VP6 nanotubes as a multifunctional template for the synthesis of nanobiomaterials functionalized with metalsBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Germán Plascencia-Villa Abstract The structural characteristics and predefined constant size and shape of viral assemblies make them useful tools for nanobiotechnology, in particular as scaffolds for constructing highly organized novel nanomaterials. In this work it is shown for the first time that nanotubes formed by recombinant rotavirus VP6 protein can be used as scaffolds for the synthesis of hybrid nanocomposites. Rotavirus VP6 was produced by the insect cell-baculovirus expression vector system. Nanotubes of several micrometers in length and various diameters in the nanometer range were functionalized with Ag, Au, Pt, and Pd through strong (sodium borohydride) or mild (sodium citrate) chemical reduction. The nanocomposites obtained were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM) with energy dispersive spectroscopy (EDS), dynamic light scattering, and their characteristic plasmon resonance. The outer surface of VP6 nanotubes had intrinsic affinity to metal deposition that allowed in situ synthesis of nanoparticles. Furthermore, the use of preassembled recombinant protein structures resulted in highly ordered integrated materials. It was possible to obtain different extents and characteristics of the metal coverage by manipulating the reaction conditions. TEM revealed either a continuous coverage with an electrodense thin film when using sodium citrate as reductant or a discrete coverage with well-dispersed metal nanoparticles of diameters between 2 and 9,nm when using sodium borohydride and short reaction times. At long reaction times and using sodium borohydride, the metal nanoparticles coalesced and resulted in a thick metal layer. HRTEM-EDS confirmed the identity of the metal nanoparticles. Compared to other non-recombinant viral scaffolds used until now, the recombinant VP6 nanotubes employed here have important advantages, including a longer axial dimension, a dynamic multifunctional hollow structure, and the possibility of producing them massively by a safe and efficient bioprocess. Such characteristics confer important potential applications in nanotechnology to the novel nanobiomaterials produced here. Biotechnol. Bioeng. 2009; 104: 871,881. © 2009 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||