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Carbonization behavior of poly(acrylonitrile-co-itaconic acid)s having different compositions
( Ghorpade Ravindra ),조동원,홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Copolymers of acrylonitrile with itaconic acid were prepared by free radical polymerization. Thermal stabilization of copolymers was carried out at different temperatures, followed by carbonization processes. Effect of different compositions of poly(acrylonitrile-co-itaconic acid) on structural characteristics of the carbon materials were investigated by XRD, FT-IR, Raman and 4-point probe analysis. Although increased IA content in PAIs resulted in reduced carbon yield, improved growth of carbon basal plane was observed, affording low electronic resistivity. This study was expected to afford information on optimum composition of PAI precursor for high performance carbon materials.
( Ghorpade Ravindra ),조동원,홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Stereoregular polyacrylonitrile and poly(acrylonitrile-co-itaconic acid) were prepared through the complex formation between monomers and Lewis Acid during their free radical polymerization processes. Isotacticity values of the polymers were determined by 13C-NMR. FT-IR was employed for the quantitative tracking of the structural evolution of the polymer films during their thermal oxidative stabilization (TOS) processes. Cyclization, oxidation and tautomerization during TOS process were characterized and quantified by the evolution of overlapping peaks of cyclic C=C, C=N, N-H and C=O vibrations in FT-IR. Stereoregularity in the copolymers played an important role for more facile TOS processes.
Structure controlled carbon nanofiber mat as a counter electrode for dye-sensitized solar cells
( Ghorpade Ravindra ),김건희,박소현,( Mallinath S. Birajdar ),이종휘,홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Carbonaceous materials have been investigated as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). In this study, nanofiber mats composed of polyacrylonitrile (co)polymer and Pt precursors were prepared by electrospinning method. Series of thermal treatment on the mats, such as thermal oxidative stabilization, carbonization and graphitization, afforded structure-controlled carbon nanofiber/Pt mats with high electrical conductivity, large surface area and high catalytic activity. The carbon nanofiber/Pt mat was introduced in DSSC as a CE by using adhesives without major structural deformations. The DSSC exhibited good performance including high energy conversion efficiency, which was comparable to that of conventional DSSC with all Pt CE.
Ghorpade, Ravindra V.,Cho, Dong Won,Hong, Sung Chul Elsevier 2017 Carbon Vol.121 No.-
<P>Due to the spatial alignment of the nitrile groups and their involvement in the cyclization reactions during thermal oxidative stabilization (TOS) procedures, stereoregularity of polyacrylonitrile (PAN) precursors is one of the most important structural parameters to afford carbon materials. To elucidate this, PAN and poly(acrylonitrile-co-itaconic acid) with higher degree of isotacticity were prepared through template-assisted free-radical polymerization in the presence of MgCl2. Fourier-transform infrared spectroscopy was employed to quantitatively track the structural evolutions of the PAN (co) polymer precursors during their TOS procedures. The improved TOS efficiencies of the precursors were evidenced by high extents of cyclization, high concentrations of cyclized rings and enhanced oxygen uptakes of the isotactic PAN (co) polymers during the TOS procedures. The isotactic PAN (co) polymer precursors also exhibited relatively large heat evolutions with broad exothermic curves in differential scanning calorimetry observations, further suggesting efficient TOS procedures with safer processing conditions. The efficient TOS procedures of the isotactic PAN (co) polymer precursors resulted in carbon materials with high degrees of crystallinity and high amounts of sp(2) clusters, affording much improved electrical conductivities. This study provided knowledge on the structural characteristics of the precursors for carbon materials with pre-designed properties, which is critical for their success in high-end applications. (C) 2017 Elsevier Ltd. All rights reserved.</P>
조동원,( Ghorpade Ravindra ),홍성철 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Polyacrylonitrile (PAN) and poly(acrylonitrile-co-itaconic acid) (PAI) were selected as model precursors for carbon materials and prepared through free radical polymerization. Stabilization behaviors of the PAN and PAI with different itaconic acid contents were investigated by applying different dosages of electron beam irradiation without any thermal treatment. Structural evolution of PAN and PAIs during the stabilization process was investigated by using Fourier transform infrared spectroscopy (FT-IR). Crystallinity values of the polymers were determined by X-ray diffraction method. Deconvolution of the specific range of FT-IR spectra into contributing peaks allowed the quantitative tracking of the stabilization reaction by electron beam irradiation.
Prakash Alagi,Ravindra Ghorpade,장정현,Chandrashekhar Patil,Harishchandra Jirimali,Vikas Gite,홍성철 한국고분자학회 2018 Macromolecular Research Vol.26 No.8
One of the major challenges in current polymer industry is to develop renewable and sustainable alternatives to petroleum-based raw materials. In this study, soybean oil (SO) was adopted as a renewable resource to afford polyols (MSO) with predetermined primary hydroxyl values (OHVs). The MSOs were prepared through a simple thiol-ene click reaction between the SO and 2-mercaptoethanol. The OHVs of the MSOs were adjusted simply by controlling the conversion of carbon-carbon double bonds of SO to OH groups. To explore their potential applications, series of polyurethane (PU) coatings were prepared from the MSOs. The MSOs with increased OHVs afforded PU coatings with higher glass transition temperature and improved adhesion strength values. Notably, increased OHVs of MSOs afforded PU coatings with improved anticorrosion properties in 3.5 wt% NaCl corrosive medium, which was attributed to the strong adhesion and blocking characteristics of the PU coatings. This study demonstrated that the number of hydroxyl functionality of the bio-based polyols played a crucial role in controlling the characteristics of the PU coatings.
Cho, Dong Won,Ghorpade, Ravindra V.,Hong, Sung Chul Applied Science Publishers 2018 Polymer degradation and stability Vol.153 No.-
<P><B>Abstract</B></P> <P>The stabilization behavior of poly (acrylonitrile-<I>co</I>-itaconic acid) (PAI) by using electron beam irradiation (EBI) was investigated to identify the role of itaconic acid (IA). EBI was employed as a tool to generate radicals, which induced a <I>“cold”</I> stabilization reaction at room temperature and excluded ionic and thermally induced radical-mediated stabilization reactions. Fourier transform infrared spectroscopy was employed to quantitatively track the structural evolution of the PAI during stabilization. The stabilization reactions of the PAIs successfully progressed with higher EBI dosages at room temperature. More efficient cyclization reactions were observed for the PAIs with increased amounts of IA, because of the increased amorphous regions of the PAIs with a higher level of IA. The extents of the cyclization values of the PAIs normalized to their crystallinity values were similar to each other regardless of the IA contents, indicating the absence of an ionic initiation mechanism of IA at room temperature. In addition, the incorporation of IA units in PAIs increased the polarity and oxophilicity of the PAIs, thereby inducing facilitated oxygen uptake reactions, as evidenced by the high concentrations of conjugated carbonyl groups in the stabilized structures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The role of itaconic acid (IA) in precursor for carbon material is investigated. </LI> <LI> Electron beam irradiation is used to isolate radical-mediated stabilization at RT. </LI> <LI> FT-IR is employed to quantitatively track the structural evolution of precursor. </LI> <LI> IA facilitates stabilization by increasing amorphous content/polarity of precursor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>