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Chemo-responsive bilayer actuator film: fabrication, characterization and actuator response
Haldorai, Yuvaraj,Shim, Jae-Jin The Royal Society of Chemistry 2014 NEW JOURNAL OF CHEMISTRY Vol.38 No.6
<P>A chemo-responsive bilayer actuator was fabricated by cross-linking a polysaccharide based highly hydrophilic material with the polyamide-6 (PA-6) substrate. The hydrogel material was prepared by grafting the polyacrylamide (PAAm) and poly(acrylic acid) (PAA) copolymer onto carboxymethyl cellulose (CMC) [poly(AA-<I>co</I>-AAm)-<I>g</I>-CMC]. The successful grafting of the copolymer onto CMC was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. The swelling behavior of the poly(AA-<I>co</I>-AAm)-<I>g</I>-CMC hydrogel was examined at a range of pH values and ionic strengths. Fabrication of the bilayer actuator was performed by drop casting a poly(AAm-<I>co</I>-AA)-<I>g</I>-CMC solution onto a PA-6 substrate followed by subsequent cross-linking under ultraviolet radiation. Cross-linking was performed to make the material readily swellable in water but prevent complete dissolution. The actuator response was measured in both water and ethanol.</P> <P>Graphic Abstract</P><P>A bilayer actuator showing fast and stable curling/uncurling motion was prepared by photo-cross-linking poly(AAm-<I>co</I>-AA)-<I>g</I>-CMC onto PA-6. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4nj00014e'> </P>
Fabrication of [60] Fullerene Grafted Polymer: Self-Assembly Behavior in Polar Solvents
Haldorai, Yuvaraj,Islam, Muhammad Naoshad,Shim, Jae-Jin Chemic Publishing Company 2014 Asian Journal of Chemistry Vol.26 No.2
<P>In of this report we prepared anew type of [60] fullerene grafted poly(2-bromomethyl)acrylic acid. First step was the free-radical polymerization of 2-(bromomethyl)acrylic acid Wing 2,2'-azobisisobutyronitrile. Then:a nucleophilie substitution reaction was performed to substitute the bromine atoms present in the polymer with azide groups Finally the C-60 grafted polymer was prepared by the reaction of azido functionalized polymer with C-60. Results of Fourier transform infrared spectroscopy and ultraviolet visible spectroscopy indicated that the C-60 was Chemically bonded to the polymer, The aggregation behavior of the resulting polymer in polar solvents was studied by transmission electron microscopy. The resultant polymer retained both electronic property of the C-60 moiety and processability property of the polymer.</P>
Haldorai, Yuvaraj,Kim, Jun Yeong,Vilian, A.T. Ezhil,Heo, Nam Su,Huh, Yun Suk,Han, Young-Kyu Elsevier 2016 Sensors and actuators. B, Chemical Vol.227 No.-
<P><B>Abstract</B></P> <P>Cobalt oxide (Co<SUB>3</SUB>O<SUB>4</SUB>) nanospindles-decorated reduced graphene oxide (RGO) composite is prepared via thermal decomposition of a three-dimensional coordination complex precursor, cobalt benzoate dihydrazinate, at 200°C. Transmission electron microscopy reveals that Co<SUB>3</SUB>O<SUB>4</SUB> nanospindles with an average particle size of <25nm are decorated on the RGO surface. The low decomposition temperature and lack of residual impurities are significant aspects of this simple and facile method. The electrochemical performance of the proposed sensor is investigated using cyclic voltammetry and chronoamperometry. Under optimum conditions, anodic peak currents are linearly proportional to their concentrations, in the range of 1–380μM for nitrite with a regression equation of <I>I</I> (μA)=2.0660C+6.7869 (<I>R</I> <SUP>2</SUP> =0.9992). The sensor exhibits a high sensitivity of 29.5μAμM<SUP>−1</SUP> cm<SUP>−2</SUP>, a rapid response time of 5s, and a low detection of limit of 0.14μM. The proposed electrode shows good reproducibility and long-term stability. The sensor is used to determine the nitrite level in tap water with acceptable recovery, implying its feasibility for practical application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile synthesis of Co<SUB>3</SUB>O<SUB>4</SUB> nanospindles/RGO composite. </LI> <LI> The low detection limit for nitrite sensing was identified as 0.14μM. </LI> <LI> Detection of wide range (1–380μM) of nitrite concentrations. </LI> <LI> High stability and reproducibility of the composite electrode. </LI> <LI> Excellent anti-interference capacity towards various common ions. </LI> </UL> </P>
Haldorai, Yuvaraj,Huh, Yun Suk,Han, Young-Kyu The Royal Society of Chemistry 2015 New journal of chemistry Vol.39 No.11
<P>We report a simple, one-pot hydrothermal method for synthesizing tin oxide (SnO<SUB>2</SUB>) nanoparticle-decorated reduced graphene oxide (RGO) nanocomposites. Transmission electron microscopy images show that flower-like SnO<SUB>2</SUB> architectures are homogeneously dispersed onto the RGO surface. The composite exhibits a maximum specific capacitance of 396 F g<SUP>−1</SUP> (at a current density of 4.5 A g<SUP>−1</SUP>), with a capacitance retention of 92.6% even after 10 000 continuous charge/discharge cycles, which is sevenfold higher than that of pure RGO (55 F g<SUP>−1</SUP>). The high capacitance is attributed to the synergetic effect of SnO<SUB>2</SUB> and RGO. In addition, the composite shows efficient photodegradation of methylene blue under visible light. The enhanced degradation is ascribed to good adsorption and improved separation efficiency of photo-induced electron–hole pairs.</P> <P>Graphic Abstract</P><P>SnO<SUB>2</SUB>/graphene nanocomposites showed excellent capacitance with a capacitance retention of 92.6% even after 10 000 continuous charge/discharge cycles. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5nj01442e'> </P>
Haldorai, Y.,Shim, J.J. North-Holland 2014 Materials letters Vol.133 No.-
Reduced graphene oxide (RGO)/zinc oxide (ZnO) composite was synthesized via a simple and environmentally-friendly route using supercritical carbon dioxide. The structure and morphology of the resulting composite was characterized by transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The nanocomposite exhibited enhanced photocatalytic activity for hydrogen (H<SUB>2</SUB>) production from water photo-splitting because the ZnO nanoparticles on the RGO sheets can capture light energy and facilitate excited electron transfer for photocatalytic H<SUB>2</SUB> production via RGO, which acts as an efficient electron mediator.
Haldorai, Y.,Shim, J.J. North-Holland 2014 Materials letters Vol.116 No.-
This paper reports a facile and residue free synthesis of copper oxide (CuO) nanospindles by the thermal decomposition of a 3D precursor complex, copper benzoate dihydrazinate at 100<SUP>o</SUP>C. Transmission electron microscopy revealed monodispersed nanospindles with a mean diameter of approximately 22nm. X-ray diffraction and selected-area electron diffraction showed that the nanospindles were composed of a pure monoclinic phase of polycrystalline CuO. The nanospindles were also confirmed by Raman spectroscopy. The enhancement of the thermal conductivity of ethylene glycol (EG) in the presence of CuO nanospindles was examined. No surfactant was used as a dispersant. The volume fraction of CuO nanospindles suspended in EG was less than 5vol%. The thermal conductivity of the CuO nanofluids increased with increasing particle loading.