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ABSTRACT: A series of poly(methylmethacrylate-co-2-hydroxyethylmethacrylate)/polyhedral oligomeric silsesquioxanes (P(MMA-co-HEMA)/POSS) nanocomposites were synthesized by the combination of ATRP and click chemistry. The hybrid nanocomposites were characterized by FT-IR, 1H-NMR, GPC, SEM, XRD, DSC, and TGA analyses. The loading of POSS in the nanocomposites was calculated using 1H-NMR data. TGA measurements suggested that the incorporation of POSS into polymer matrices enhanced decomposition temperature as well as char yield of the polymeric materials. The glass transition temperature linearly increased with the increase of POSS loading plausibly because of the aggregation of POSS nanoparticles and the dipole-dipole interaction between POSS and P(MMA-co-HEMA) segments.
Journal of Nanoscience and Nanotechnology 03/2013; 13(3):1970-3. · 1.56 Impact Factor
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ABSTRACT: In this study, we have investigated the photocatalytic activity for the decomposition of methyl orange on the LaCoO3 perovskite-type oxides prepared using sol-gel method at different conditions. From the results of UV-Vis DRS, all the catalysts have the similar absorption spectrum up to visible region. The LaCoO3 catalyst prepared at 1.5 mol of malic acid and calcined at 350 degrees C shows the highest activity. The amount of photo absorption in the visible region is correlated with the photocatalytic activity. In addition, the chemisorbed oxygen plays an important role on the photocatalytic decomposition of methyl orange and the higher are the contents of chemisorbed oxygen, the better shows the performance of photocatalyst.
Journal of Nanoscience and Nanotechnology 03/2013; 13(3):2320-4. · 1.56 Impact Factor
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ABSTRACT: Hydroxyapatite nanocrystals (HAP NCs) were encapsulated by poly(allyl methacrylate) (PolyAMA) employing controlled surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization of allyl methacrylate to afford HAP-PolyAMA nanohybrids. The subsequent thiol-ene coupling of nanohybrids with 2-mercaptosuccinic acid resulted HAP-Poly(AMA-COOH) possessing multicarboxyl group. The formation of the nanohybrids was confirmed by FT-IR and EDS analyses. The TGA and FE-SEM investigation were further suggested the grafting of PolyAMA onto HAP NCs. The utility of the HAP-PolyAMA nanohybrid as drug carrier was also explored. The pendant carboxyl groups on the external layers of nanohybrids were conjugated with anticancer drug cisplatin to afford HAP-Poly(AMA-COOH)/Pt complex. The formation of the complex was confirmed by FT-IR, XPS, and FE-SEM. In vitro evaluation of the synthesized complex as nanomedicine revealed its potential chemotherapeutic efficacy against cancer cell lines.
Journal of Colloid and Interface Science 01/2013; · 3.07 Impact Factor
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ABSTRACT: Biocompatible magnetic nanocomposites of Fe-AuNPs and poly(2-hydroxylethyl methacrylate) (PHEMA) were employed as a strategic protein immobilization platform. The hybrid magnetic nanocomposites were prepared by applying a 'grafting to' ATRP protocol. Fe-AuNPs having Fe core and Au shell were initially prepared by the inverse micelle method. Disulfide-containing PHEMA (DT-PHEMA) was grafted to the Fe-AuNPs surface by taking the advantages of the thiol chemistry. The grafting of DT-PHEMA to the Fe-AuNPs was confirmed by relevant spectroscopic analyses. The superparamagnetic property, a basic requirement for facile protein immobilization, of the magnetic nanocomposites was measured by the SQUID analysis. Lysozyme, gamma-globulins and bovine serum albumin (BSA) were immobilized onto magnetic nanocomposites via the adsorption strategy. The absorption intensity of lysozyme, gamma-globulins and BSA on the PHEMA grafted Fe-AuNPs were observed to be higher than that of bare Fe-AuNPs.
Journal of Nanoscience and Nanotechnology 01/2013; 13(1):603-6. · 1.56 Impact Factor
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ABSTRACT: ZnO nanoparticles were covalently wrapped by polystyrene (PS) through surface thiol-lactam initiated radical polymerization using the grafting from approach. The surface of ZnO nanoparticles was initially modified by 3-mercapto propyltrimethoxysilane to afford thiol functionalized ZnO nanoparticles (ZnO-SH). The controlled radical polymerization of styrene (St) was subsequently accomplished by using an initiating system of ZnO-SH and butyrolactam. FT-IR, XPS, XRD, TGA, DSC, TEM and DLS were employed to investigate the chemical structure, morphology, thermal properties, the size and size distribution of nanocomposites. The dispersibility of ZnO nanoparticles was observed to be significantly improved upon functionalization by PS brushes. The controlled nature of the surface initiated thiol-lactam aided polymerization of St from the ZnO nanoparticles surface was confirmed by GPC analysis.
Journal of Nanoscience and Nanotechnology 01/2013; 13(1):694-7. · 1.56 Impact Factor
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ABSTRACT: An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.
Journal of Nanoscience and Nanotechnology 07/2012; 12(7):5976-80. · 1.56 Impact Factor
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ABSTRACT: Diluted magnetic semiconductor (DMS) nanoparticles of Sn1−x
Er
x
O2 (x=0.0, 0.02, 0.04, and 0.1) were prepared by sol–gel method. The X-ray diffraction patterns showed SnO2 rutile structure for all samples with no impurity peaks. The decrease in crystallite size with Er concentration was confirmed
from TEM measurements (from 12 to 4nm). The UV–Visible absorption spectra of Er-doped SnO2 nanoparticles showed blue shift in band gap compared to undoped SnO2. The electron spin resonance analysis of Er-doped SnO2 nanoparticles indicate Er3+ in a rutile lattice and also decrease in intensity with Er concentration above x=0.02. Temperature-dependent magnetization studies and the inverse susceptibility curves indicated increased antiferromagnetic
interaction with Er concentration.
KeywordsDMS–Nanoparticles–SnO2:Er–ESR–Magnetic studies–Electron spin
Journal of Nanoparticle Research 05/2012; 13(10):4623-4630. · 3.29 Impact Factor
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ABSTRACT: Poly(1-hexyne) was prepared by the polymerization of 1-hexyne by using transition metal catalyst. The instrumental analysis
data on the polymer structure revealed that the poly(1-hexyne) have the conjugated polyene backbone structure with n-butyl
substituents. Poly(1-hexyne) showed UV-visible absorption band at 276 nm and PL spectrum at 415 nm, indicating relatively
blue-shifted PL maximum value. From the relationship plot of the oxidation current density (log i
p,a) as a function of the scan rate (log v), it was found that the oxidation current of poly(1-hexyne) versus the scan rate is approximately linear relationship in
the range of 30∼150 mV/sec and the exponent of scan rate, x value is found to be 0.424. It is explained by that the kinetics
of the redox process are close to the diffusion-control process. The band gap energy of poly(1-hexyne) was estimated to be
2.98 eV and HOMO and LUMO level values of poly(1-hexyne) were 5.35 and 2.37 eV, respectively.
KeywordsPoly(1-hexyne)–Conjugated polymer–Characterization–Cyclovoltamogram–Photoluminescence
Fibers and Polymers 05/2012; 12(3):291-295. · 0.84 Impact Factor
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ABSTRACT: Graphene oxide films were prepared by a facile ball milling process. The milling time and the amount of the acryl type polymer dispersion agent were controlled to obtain well dispersed graphene oxide solution in ethanol. Consequently, the transparent and conducting graphene oxide film which had 69% transmittance and 1.5 x 10(6) ohm/sq surface resistance was produced by bar coating the solution on a PET substrate. The electrical property of the graphene oxide film could be further improved to 2.1 x 10(5) ohm/sq by hydrazine vapor reduction.
Journal of Nanoscience and Nanotechnology 05/2012; 12(5):4294-8. · 1.56 Impact Factor
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ABSTRACT: A new water-soluble ionic conjugated polymer, poly[N-(carboxymethyl)-2-ethynylpyridinium bromide], was prepared by the activated polymerization of 2-ethynylpyridine by using bromoacetic acid. This polymerization proceeded well in mild reaction conditions without any additional initiator or catalyst. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system with the designed functional groups. The photoluminescence spectrum of polymer showed that the PL peak is located at 603 nm corresponding to the photon energy of 2.06 eV. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of the redox process of polymer is almost controlled by the reactant diffusion process from the oxidation current density of polymer versus the scan rates.
Journal of Nanoscience and Nanotechnology 05/2012; 12(5):4361-4. · 1.56 Impact Factor
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ABSTRACT: Fabrication of a hybrid consists of gold nanoparticles and multi walled carbon nanotubes (MWCNTs) with the help of poly (amino acid) was investigated. Poly(acryloyl beta-alanine) was synthesized by precipitation polymerization in tetrahydrofuran. The polymers were used to form hybrids with MWCNTs in aqueous media. Subsequently, the polymer functionalized MWCNTs were fabricated by in situ formed gold nanoparticles. The fabrication by gold nanoparticles was confirmed by transmission electron microscopic analyses. The fabrication was attempted with different concentrations of lithium auric chloride solutions in the range of 0.1-1.2 mM in water. The lower concentration of the gold precursor solution resulted in the formation and attachment of gold nanoparticles without aggregation while the higher concentration above 1.0 mM led to the aggregation of gold nanoparticles. The gold nanoparticles were observed only on the surface of MWCNTs and none was in the bulk aqueous phase.
Journal of Nanoscience and Nanotechnology 05/2012; 12(5):4384-7. · 1.56 Impact Factor
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ABSTRACT: Polymer/layered silicate nanocomposites, in which an inorganic solid is associated with organic entities interacting at the
nano-level, have attracted great interest in many research fields because of their enhanced properties compared to conventional
microcomposites. As a rule, the homogeneous dispersion of 3mass% to 5mass% of thin clay layers improves the mechanical and
thermal properties of the polymer matrix to the same extent as 30mass% to 50mass% of micro-sized fillers. In this study,
poly(methylmethacrylate) PMMA/clay(C10A) layered nanocomposites were prepared by in situ polymerization with a microwave process.
The influence of the amount of clay on the structure and thermal properties of the synthesized nanocomposites were characterized
by means of X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermo-gravimetric analysis,
and photoacoustic spectroscopy. It was found that the structure of nanocomposites, an intercalated/exfoliated structure, strongly
depended on the clay content.
International Journal of Thermophysics 04/2012; · 0.95 Impact Factor
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ABSTRACT: To overcome the environmental concerns associated with long-chain perfluorinated compounds, in this report, non-bioaccumulative,
environmentally friendly stabilizer architectures based on short-chain fluorinated polymers have been designed for the dispersion
polymerization of methyl methacrylate (MMA) in supercritical CO2. Random copolymers composed of 2-(diisopropylamino)ethyl methacrylate (DPAEMA) and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate
(FBMA) or 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate were prepared with various comonomer ratios and utilized as stabilizers.
It was found that the copolymers effectively stabilized PMMA latexes in CO2, leading to the formation of free-flowing, spherical PMMA particles. With increase in the concentration of the stabilizer
poly(FBMA-co-DPAEMA) from 2% to 6% (w/w with respected to MMA), the particles diameter decreased from 3.02 to 1.0μm.
Colloid and Polymer Science 04/2012; 286(6):843-848. · 2.33 Impact Factor
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ABSTRACT: Lead–tin (Pb–Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties Lead–tin (Pb–Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties
required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity
of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research
and development studies of lead-free solders. The Sn–Ag–Cu ternary eutectic alloy is considered to be one of the promising and development studies of lead-free solders. The Sn–Ag–Cu ternary eutectic alloy is considered to be one of the promising
alternatives. Except for thermal properties, much research on several properties of Sn–Ag–Cu alloy has been performed. In alternatives. Except for thermal properties, much research on several properties of Sn–Ag–Cu alloy has been performed. In
this study, five Sn–xAg–0.5Cu alloys with variations of Ag content x of 1.0mass%, 2.5mass%, 3.0mass%, 3.5mass%, and 4.0mass% were prepared, and their thermal diffusivity and specific heatpared, and their thermal diffusivity and specific heat
were measured from room temperature to 150°C, and the thermal conductivity was calculated using the measured thermal diffusivity, were measured from room temperature to 150°C, and the thermal conductivity was calculated using the measured thermal diffusivity,
specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170°C. The results specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170°C. The results
show that Sn–3.5Ag–0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion, show that Sn–3.5Ag–0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion,
which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability. which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability.
International Journal of Thermophysics 04/2012; 30(4):1234-1241. · 0.95 Impact Factor
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ABSTRACT: Multiwalled carbon nanotubes (MWNTs) were functionalized with poly(3,4-propylenedioxythiophene) (PProDOT) using a simple “chemical
grafting” approach. After the conventional acid oxidation (AO) process, the MWNT-COOH was converted to the acyl chloride functionalized
MWNTs (MWNT-COCl) by treating them with thionyl chloride. The MWNT-COCl were further reacted with a functionalized monomer
based on 3,4-propylenedioxythiophene (ProDOT-OH), followed by oxidative polymerization to prepare the MWNT-g-PProDOT hybrid. The monomer-functionalized MWNTs was further copolymerized with thiophene to prepare conducting copolymers
on carbon nanotubes (CNTs). Fourier-transformed infrared spectrophotometry was employed to characterize the change in surface
functionalities, which revealed that the PProDOT was covalently grafted to the MWNTs, while TGA was used to study the weight
gain due to the functionalization. UV–Vis absorption spectra revealed the functionalization of the conjugated polymer by showing
the typical absorption band. The morphology micrographs of the grafted PProDOT on MWNTs as evidenced by field emission scanning
electron microscopy and transmission electron microscopy showed apparent effect on the structure and appearance of the MWNTs
by growing thicker as expected from surface modification. Using the facile route developed in this study, CNTs can be easily
fabricated with other types of polymers for several applications.
Colloid and Polymer Science 04/2012; 287(1):97-102. · 2.33 Impact Factor
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ABSTRACT: The effect substitution of Ti4+ at the Fe4+ site in a CaFe2O4-MgFe2O4 bulk hetero-junction (BH) lattice photocatalyst was explored and the Ti ion concentration was optimized to fabricate an efficient photocatalyst. A BH consisting of an optimum dopant concentration (Ti+4) level of x = 0.03 exhibited an increased band gap and generated a 1.5 times higher photocurrent. The newly fabricated Ti ion doped photocatalyst showed an enhanced quantum yield (upto similar to 13.3%) for photodecomposition of a H2O-CH3OH mixture, as compared to its undoped BH counterpart under visible light (lambda a parts per thousand yen 420 nm). In contrast, the material doped with a very high Ti-dopant concentration displayed deteriorated photochemical properties. An efficient charge-separation induced by Ti-ion doping seems to be responsible for the higher photocatalytic activity in a doped bulk BH.
Journal- Korean Physical Society 01/2012; 61(1):73-79. · 0.45 Impact Factor
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ABSTRACT: Composite materials of multi-walled carbon nanotubes (MWNTs) and a conducting polymer, poly(3-thiophene boronic acid) (PTBA) were prepared by in-situ oxidative polymerization of TBA in the presence of MWNTs and potassium dichromate. The MWNTs which were previously surface functionalized with acid chloride groups were reacted with TBA using a simple "chemical grafting" technique. It was observed that the nanotubes were dispersed uniformly in the pi-conjugated polymer matrix and entrapped by the polymer. The conductivity of the composites was higher than that of the pure polymer from a conventional four-probe technique, which indicates that the fabrication of MWNTs into the polymer matrix significantly improves the conductivity of the polymer due to the intrinsic properties of MWNTs.
Journal of Nanoscience and Nanotechnology 01/2012; 12(1):754-9. · 1.56 Impact Factor
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ABSTRACT: Water-soluble polymer brushes with multi-walled carbon nanotubes (MWNTs) as backbones were synthesized by grafting 2-hydroxyethyl methacrylate (HEMA) from surface functionalized MWNTs via in situ surface thiol-lactam initiated radical polymerization. MWNTs were functionalized with 2-mercaptoethanol and used as initiators in the polymerization of HEMA in the presence of butyrolactam. FT-IR, XPS, 1H NMR, GPC and TGA were used to determine chemical structure and the grafted polymer quantities of the resulting product. The covalent bonding of PHEMA to the MWNTs dramatically improved the water dispersibility of MWNTs. The average thicknesses of the polymer brushes in the functionalized MWNTs were detected with electron microscopy (SEM and TEM) and images indicated that the nanotubes were coated with polymer layer.
Journal of Nanoscience and Nanotechnology 01/2012; 12(1):840-6. · 1.56 Impact Factor
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Journal of Polymer Science Part A Polymer Chemistry 08/2011; 49(21):4680 - 4686. · 3.92 Impact Factor
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ABSTRACT: Single walled carbon nanotube (SWNT)/graphene oxide (GO) hybrid films were prepared by a facile bar coating method on a polyethylene terephthalate substrate using a mixed solution of SWCNTs and GO. An acryl type polymer was employed as a dispersion agent to obtain SWCNT and GO suspension in ethyl alcohol. The SWCNT/GO hybrid films were highly transparent and electrically conductive, showing 80% transmittance and 1.8 x 10(3) ohm/sq surface resistance. The surface resistance of the SWCNT/GO film could be further improved to 750 ohm/sq by hydrazine vapor reduction.
Journal of Nanoscience and Nanotechnology 08/2011; 11(8):7424-7. · 1.56 Impact Factor
