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Superhydrophobic mesoporous material as a pH-sensitive organic dye adsorbent
Saravanan Nagappan,이단비,서덕진,박성수,하창식 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-
A superhydrophobic material was synthesized using a one-pot approach via the self-hydrolysis andcondensation of polymethylhydrosiloxane (PMHS) under a base catalyst in ethanol and water media. Theobtained superhydrophobic polymethylhydroxysiloxane (PMHOS) material was stable up to temperaturesas high as 500 8C, even under strong acidic and basic pH conditions. The micro–nano particles ofPMHOS exhibited a hierarchical morphology with a mesoporous structure. The superhydrophobicPMHOS, however, become superhydrophilic by calcination at 600 8C. The superhydrophobic andsuperhydrophilic PMHOS exhibited a good ability to adsorb organic dyes at a certain pH (pH 12).
Saravanan Nagappan,조남주,이원기,하창식 한국고분자학회 2017 Macromolecular Research Vol.25 No.5
We prepared novel hybrid materials by in situ self-hydroxylation and condensation of polymethylsiloxane (PMHS) with multi-walled carbon nanotubes (MWCNTs). The hybrid material showed superhydrophobic and non-stick properties, mesoporous structure, and liquid marble-like non-stick water droplet behavior. Moreover, we found that the in situ addition of MWCNTs to the PMHS would increase the thermal stability of the hybrid material. Thermal stability of the hybrid is enhanced by increasing the percentage of MWCNTs to the PMHS. The superhydrophobic hybrid powder covered non-stick water droplet showed anti-icing behavior for long time. The hybrids also showed oils sorption behavior and easy reusable property. The obtained results suggest that the thermally stable superhydrophobic hybrid mesoporous materials with anti-icing, oils sorption properties can be easily synthesized and used for various applications.
Saravanan Nagappan,최면천,성기주,박성수,Madhappan Santha Moorthy,추상욱,이원기,하창식 한국고분자학회 2013 Macromolecular Research Vol.21 No.6
Organic-inorganic hybrids were synthesized using polymethylhydrosiloxane, 2,2,3,4,4,4 hexafluorobutylmethacrylate and tetraethyl orthosilicate with a platinum catalyst. The resulting hybrids formed transparent thin films on glass substrate by spin coating. The functional groups, molecular structure, surface morphology and chemical composition of the hybrids were analyzed by 1H nuclear magnetic resonance spectroscopy (NMR), 29Si MASNMR spectroscopy, high resolution scanning electron microscopy with energy-dispersive X-ray spectroscopy,atomic force microscopy, and X-ray photoelectron spectroscopy. The thermal stability, mechanical scratch resistance,static and advancing/receding dynamic contact angles were measured by thermogravimetry, the pencil hardness test and a drop shape analysis system. The prepared hybrid thin films exhibited good transparency, hydrophobicity,as well as good mechanical and anti-stain properties.
Saravanan Nagappan,하창식 한국고분자학회 2014 Macromolecular Research Vol.22 No.8
Superhydrophobic and self-cleaning hybrid micro-nanocomposite was prepared using a tree leaf (Ailanthusaltissima) powder and polysiloxane. The functional group and the chemical compositions in the hybrid micronanocompositeswere analyzed by Fourier transform infra-red spectroscopy, 29Si cross polarization magic anglespinning nuclear magnetic resonance spectroscopy, X-ray diffraction pattern and X-ray photoelectron spectroscopy. The composites showed micro-nano hierarchical surface morphology and excellent superhydrophobicity on anysubstrate, regardless of the coating processes (drop coating, spin coating and dip coating, followed by solventevaporation). The surface maintained the superhydrophobicity at high temperatures (400-500 ºC) and becamesuperhydrophilic at 600 ºC. The prepared hybrids have a mesoporous structure, and excellent non-stick and selfcleaningproperties.
Nagappan, Saravanan,Park, Sung Soo,Kim, Bo Kyung,Yoo, Dae-Geon,Jo, Nam-Ju,Lee, Won-Ki,Ha, Chang-Sik The Royal Society of Chemistry 2018 New Journal of Chemistry Vol.42 No.12
<P>Herein, we propose a facile method for the synthesis of functionalised mesoporous silica nanoparticles (MSN) <I>via</I> the polymerisation of <I>N</I>-isopropylacrylamide (NIPAM) monomer with vinyl functional mesoporous silica nanoparticles (VMSN). The structural and functional properties of the materials are analysed using various characterisation techniques. Additionally, a transparent hydrophobic glass substrate is fabricated by dispersing a certain amount of the synthesised nanoparticles in ethyl acetate (EA) followed by spin-coating on a glass substrate and drying overnight at 80 °C. In summary, the functionalised mesoporous materials can be used for multiple applications such as the preparation of stable hydrophobic, transparent, and temperature-sensitive surfaces, as well as for the adsorption of Rhodamine B dye.</P>
Duraivel, Malarkodi,Nagappan, Saravanan,Balamuralitharan, B.,Selvam, S.,Karthick, S. N.,Prabakar, K.,Ha, Chang-Sik,Kim, Hee-Je The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.13
<P>In this work, we report the synthesis of sulfur-doped reduced graphene oxide (S-rGO) using sodium borohydride (NaBH4) and sodium sulfide (Na2S) by a facile one-pot approach <I>via</I> refluxing in deionised water. The undoped rGO chemical structure is partially reduced by NaBH4, whereas the addition of a small amount of Na2S with NaBH4 resulted in a better reduction of rGO. XPS analysis confirmed the successful doping of sulfur and Raman spectroscopy verified the increased defect density. The S-rGO electrode exhibits good power density (3202 W kg<SUP>−1</SUP>) with increased specific capacitance (392 F g<SUP>−1</SUP>) and cyclic stability (91%, 2000 cycles) in 1 M Na2SO4 aqueous electrolyte. The obtained results suggest that the simple tuning of the graphene oxide structure using Na2S with NaBH4 enhances the above properties. Moreover, this method is facile and allows the easy reproduction of bulk quantities of materials for use in commercial applications.</P>
Jeong, Keuk-Min,Park, Sung Soo,Nagappan, Saravanan,Min, Guoquan,Zhang, Yongxu,Qu, Minming,Zhang, Yan,Ha, Chang-Sik Elsevier Sequoia 2019 Progress in organic coatings Vol.134 No.-
<P><B>Abstract</B></P> <P>Highly transparent organic-inorganic hybrid UV-curable coating formulations were obtained using silica particles with different functional groups, such as methyl group, long alkyl chain, benzene ring, isobutyl group, and fluorine group. Their surface chemical structures were analyzed by attenuated total reflection-flourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The surface morphology of the hybrid UV-curable coating formulated materials was observed by atomic force microscopy and high-resolution scanning electron microscopy. The hydrophobic and oleophobic properties were investigated by contact angle measurements using water, hexadecane, and artificial fingerprint solution. The prepared hybrid UV-curable coating materials exhibited excellent transparency, good hydrophobic, and oleophobic properties in addition to the high thermal stability and high pencil hardness up to 8H. In particular, the hybrid UV-curable coating materials with a small amount of fluorine-functionalized silica showed balanced coating performance, such as high pencil hardness (6 H) and good amphiphobic properties (static contact angles in water (135°), oil (100°), and artificial fingerprint solution (114°)), as well as excellent transparency of more than 95% of transmittance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Surface morphology, amphiphobicity, scratch resistance, and transparency were controlled by functionalized silica particles. </LI> <LI> Alkyl chain length on surface of silica particle changed surface roughness, which can impart a physical resistance effect. </LI> <LI> UV curable silica hybrid coating materials exhibited high contact angles in water, oil, artificial fingerprint solution. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>