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RISS 인기검색어
- 검색키워드
- 저자 : Nhat Tri Vo (검색결과 4 건)
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Vo, Nhat Tri,Patra, Astam K.,Kim, Dukjoon The Royal Society of Chemistry 2018 New journal of chemistry Vol.42 No.7
<P>A decrease in the coefficient of thermal expansion of poly(ether sulfone) films is achieved through the incorporation of hollow doughnut shaped mesoporous silica nanoparticles (hd-MSNs). A new class of silica nanoparticles with an unprecedented structural morphology is synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), l-arginine, and ammonium metatungstate (AMT) composite templates, all in aqueous ethanol. 46.1% and 48.0% decreases in the coefficient of thermal expansion (CTE) of poly(ether sulfone) films are observed in the range of 30-90 °C and 30-150 °C, respectively, when 2.0 wt% of hd-MSNs are loaded. Furthermore, the small size (<50 nm diameter) of doughnut shaped mesoporous silica nanoparticles helps to decrease light scattering, and thus maintains the high transmittance of the nanocomposite films. The effect of the hd-MSN was also investigated on both the thermal and mechanical stability. We expect that the hd-MSN synthesized in this study can be used as a promising filler to improve the thermal and mechanical stability of the PES substrate without losing its optical transparency.</P>
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Vo, Nhat Tri,Patra, Astam K.,Kim, Dukjoon American Chemical Society 2018 Langmuir Vol.34 No.13
<P>The new class of silica nanoparticles with unprecedented structural morphology is synthesized by hydrolysis of tetraethyl orthosilicate (TEOS) in the presence of cetyltrimethylammonium bromide (CTAB), <SMALL>L</SMALL>-arginine, and ammonium metatungstate (AMT) composite template, all in aqueous ethanol. The morphology of the synthesized mesoporous silica nanoparticles (MSNs) can be tuned from a spherical to a hollow doughnut shape through a hollow sphere by controlling the concentration of AMT in the composite template. The formation mechanism of the hollow doughnut shaped MSNs (hd-MSNs) is well-explored by means of zeta potential, high-resolution transmission electron microscopy (HRTEM) with elemental mapping analysis, and X-ray photoelectron spectroscopy. The unique structure of the hd-MSNs as well as their high thermal and mechanical stability is expected to result in their application in shape-selective catalysis, drug-delivery, and sensors.</P> [FIG OMISSION]</BR>
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Nhat Tri Vo,김덕준 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9
Cetyltrimethylammonium bromide (CTAB) was used as a stabilizing agent for PES films, and its effect on the coefficient of thermal expansion (CTE) and optical transmittance (OT) of PES films was investigated. The CTE of PES film decreased with increasing CTAB concentration up to 0.5 wt%, because of the improved intermolecular interaction between polymer chains via CTAB molecules. When 0.5 wt% of CTAB was added to the PES film, the CTE of polymer film decreased from 66 to 50 ppm/oC without noticeable reduction in OT. At such a low CTAB concentration range (<0.5 wt%), the glass transition temperature (Tg) and tensile strength increased with CTAB. At high CTAB concentration above 0.5 wt%, however, it had a negative effect on the properties of PES film - CTE increased but Tg and tensile strength decreased with it.
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Patra, Astam K.,Vo, Nhat Tri,Kim, Dukjoon Elsevier 2017 Applied Catalysis A Vol.538 No.-
<P><B>Abstract</B></P> <P>This work reports on additive-free Ag nanoparticles (4–6nm) deposition on magnetic α-Fe<SUB>2</SUB>O<SUB>3</SUB> nanocrystals surface by the slow reduction of AgNO<SUB>3</SUB> with NaBH<SUB>4</SUB> in aqueous medium. The EDS analysis revealed that the new materials contain 3.93wt% of Ag nanoparticle on the surface of α-Fe<SUB>2</SUB>O<SUB>3</SUB> which are the active suite for hydrogenation reaction. The Ag/Fe<SUB>2</SUB>O<SUB>3</SUB> nanocatalysts exhibited good catalytic ability toward chemoselective hydrogenation of nitroarenes in water. LC–MS study suggested that the catalytic reaction pathway is NO<SUB>2</SUB>, NHOH, NH<SUB>2</SUB> and certainly skips the nitrosoarene intermediate step. The nanocatalysts are very efficient in the hydrogenation of nitroarenes tolerating H, Br, I, OH, OCH<SUB>3</SUB>, COOH and CONH<SUB>2</SUB> functional groups. The nanocatalysts were separated by external magnet and recycled in aqueous medium which offer environmentally and safe approach to this hydrogenation reaction. The catalyst was tested up to 10 recycles and showed no significant loss of catalytic activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient Ag nanoparticles incorporated magnetic α-Fe<SUB>2</SUB>O<SUB>3</SUB> nanocatalyst were developed by simple method. </LI> <LI> 4–6nm Ag nanoparticles on the surface of α-Fe<SUB>2</SUB>O<SUB>3</SUB> are the active suite for the high catalytic activity. </LI> <LI> LC–MS study suggested that the catalytic reaction pathway is NO<SUB>2</SUB>, NHOH, NH<SUB>2</SUB> and certainly skips the nitrosoarene intermediate step. </LI> <LI> The nanocatalyst are very efficient in the hydrogenation of nitroarenes tolerating H, Br, I, OH, OCH<SUB>3</SUB>, COOH, and CONH<SUB>2</SUB> functional groups in water. </LI> <LI> High catalytic activity and excellent recyclability and can be separated by external magnet and no significant loss of catalytic activity after 10 recycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
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