• Macromolecular Research
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• v.17 no.5
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• pp.301-306
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• 2009

This work has demonstrated that a novel amphiphilic poly(epichlorohydrine)-graft-polystyrene (PECH-g-PS) copolymer at 34:66 wt% was synthesized via atom transfer radical polymerization (ATRP) of styrene using PECH as a macroinitiator. The structure of the graft copolymer was characterized by nuclear magnetic resonance ($^1H$ NMR) and FTIR spectroscopy, demonstrating that the "grafting from" method using ATRP was successful. The self-assembled graft copolymer was used as a template film for the in-situ growth of silver nanoparticles from $AgCF_3SO_3$ precursor under UV irradiation. The in situ formation of silver nanoparticles with 6-8 nm in average size in the solid state template film was confirmed by transmission electron microscopy (TEM), UV-visible spectroscopy and wide angle X-ray scattering (WAXS). Differential scanning calorimetry (DSC) also displayed the selective incorporation and the in situ formation of silver nanoparticles within the hydrophilic PECH domains, probably due to stronger interaction of the silvers with the ether oxygens of PECH backbone than that with hydrophobic PS side chains.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.83-91
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• 2011

Mesoporous titanium dioxide ($TiO_2$) thin films were prepared using poly(vinyl chloride)-graft-poly(N-vinyl pyrrolidone) (PVC-g-PVP) as a templating agent via sol-gel process. Grafting of PVC chains from PVC backbone was done by atom transfer radical polymerization (ATRP) technique. The successful grafting of PVP to synthesize PVC-g-PVP was checked by fourier-transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). The carbonyl group interaction of PVC-g-PVP graft copolymer with $TiO_2$ was confirmed by FT-IR. The porous morphologies of the $TiO_2$ films genereated after calcination at $450^{\circ}C$ was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mesoporous $TiO_2$ films with 580 nm in thickness were used as a photoelectrode for solid state dye sensitized solar cell (DSSC) and showed an energy conversion efficiency of 1.05% at 100 $mW/cm^2$.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.866-871
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• 1997

The com starch was treated with propylene oxide, 1,2-epoxybutane, glycidyl methacrylate, maleic anhydride, caprolactone, respectively, in order to alter the hydrophilicity and the reactivity of starch. When the starch was not dried, poor reaction was observed except the reaction with propylene oxide or maleic anhydride. The treated starches were grafted with styrene by several different polymerization methods. Solution polymerization and redox polymerization using cerium(IV) ion show poor grafting efficiency and poor yield. Encapsulation of starch with polystyrene by suspension polymerization was difficult due to the hydrophilicity of the starch. Among the examined methods, emulsion polymerization was found to be the suitable way to graft styrene onto starch.

• Journal of Sericultural and Entomological Science
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• v.34 no.1
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• pp.49-56
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• 1992

Treatment of vinyl monomers onto silk fiber modifies the properties of the original silk fiber considerably. This field has been the subject of investigation by many workers using chemical and radiation initiation. Many studies on the reaction conditions, polymerization mechanism, physical properties and practical performances of methacrylamide-treated silk fiber have been continued. However, the polymerization mechanism has not been clearly revealed yet and this remains ambiguously whether the grafting is formed on fiber or not. In general, it has been accepted that free radicals were formed and vinyl monomers were polymerized in silk fibroin by graft polymerization mechanism, while active sties were varied by the types of monomer and initiator as well as by the reaction conditions. On the other hand, there is another argument on polymerization mechanism, in which monomers are polymerized and impregnated in the internal side of the fiber by homopolymerization. Though a large number of analytical methods are used to examine the polymerization mechanism of methacrylamide-treated silk fiber, the results on the basis of thermal analysis are merely reported in this paper. In differential scanning calorimetry (DSC) analysis, the thermal decomposition behaviors of the methacrylamie-treated silk fibers were determined and compared to those of the controlled silk fibers. DSC curves obtained from the methacrylamide-treated silk fibers showed double peaks at around 290$^{\circ}C$ (A peak) and 320$^{\circ}C$ (B peak) which are attributed to the thermal decomposition of the methacrylamide polymer and silk fibroin fiber, respectively. The temperature of A and B peak shifted to higher value with the increase of add-on. Also, the moisture regain of the treated silk fibers increased with add-on.

• Membrane Journal
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• v.21 no.2
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• pp.193-200
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• 2011

An amphiphilic graft copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). Mesoporous titanium dioxide $(TiO_2)$ films with crystalline anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA graft copolymer. Titanium isopropoxide (TTIP), a $TiO_2$ precursor was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grew to form mesoporous $TiO_2$ films, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amounts of P25 nanoparticies. The energy conversion efficiency reached up to 2.7% at 100 mW/$cm^2$ upon using quasi-solid-state polymer electrolyte.

• Membrane Journal
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• v.19 no.2
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• pp.96-103
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• 2009

A series of organic-inorganic composite membranes from poly(vinyl chloride) (PVC) graft copolymer electrolyte and heteropolyacid (HPA) were prepared for proton conducting membranes. First, poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA) was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC. HPA nanoparticles were then incorporated into the PVC-g-PSSA graft copolymer though the hydrogen bonding interactions, as confirmed by FT-IR spectroscopy. The proton conductivity of the composite membranes increased from 0.049 to 0.068 S/cm at room temperature with HPA contents up to 0.3 weight traction of HPA, presumably due to both the intrinsic conductivity of HPA particles and the enhanced acidity of the sulfonic acid of the graft copolymer. The water uptake decreased from 130 to 84% with the increase of HPA contents up to 0.45 of HPA weight traction, resulting from the decrease in number of water absorption sites due to hydrogen bonding interaction between the HPA particles and the polymer matrix. Thermal gravimetric analysis (TGA) demonstrated the enhancement of thermal stabilities of the composite membranes with increasing concentration of HPA.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.343-348
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• 2010

The surface of low density polyethylene (LDPE) film was oxyfluorinated under different reaction conditions to introduce hydroperoxide groups and change surface characteristics. Hydroperoxide functional groups created by oxyfluorination were used as active sites for graft polymerization with hydrophobic monomer, acryl amide (AM), and hydrophilic monomer, methyl methacrylate (MMA) to carry out the second modification of the LDPE film surface. The surface properties of the OFPE films and grafted OFPE films were characterized by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method, ATR-IR, contact angle measurement and DSC. From the results of DPPH method, the amount of hydroperoxide groups on the oxyfluorinated LDPE film continuously increased as the total pressure in the oxyfluorination and the partial pressure of fluorine gas increased. The water contact angle and surface free energy measurements showed that hydrophilic liquid (water) contact angle on LDPE film surface decreased with hydrophilic AM grafting and hydrophobic liquid (methylene diiodide) contact angle on LDPE film surface decreased with hydrophobic MMA grafting. These were attributed to AM or MMA monomer grafting and the wettability of LDPE filmsurface to hydrophilic and hydrophobic liquids were improved.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.1-12
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• 2009

This miniaccount presents the selective examples of our recent discoveries in the photopolymerization of vinyl monomers using the organic initiators such as hydrosilanes, poly(hydroarylsilane)s, benzoin silyl ethers, and thianthrene cation radical. In the photopolymerization of vinyl monomers with silanes polysilanes, while the polymerization yields and polymer molecular weights of the poly(MMA)s containing the silyl moieties decreased, the TGA residue yields and intensities of SiH stretching IR bands increased as the mole ratio of the silanes over MMA increased. The hydroarylsilane and poly(hydroarylsilane) seemed to influence strongly on the photopolymerizaiton of olefinic monomers as both chain initiation and chain transfer agents. For the photohomopolymerization and photocopolymerization of MA and AA, the similar trends were observed. Benzoin silyl ethers and thianthrene cation radical also exhibit the photoinitiating ability in the photopolymerization of MMA.

• Polymer(Korea)
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• v.34 no.1
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• pp.58-62
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• 2010

The acrylic monomers were graft-polymerized to starch as matrix polymer by emulsion polymerization. Viscosity and particle size of the emulsion were increased with starch contents due to interaction with water and particle swelling toward the water phase by hydroxy group of starch. Chemical stability of the emulsion was also increased with enhancement of starch, but water and alkali resistance were reduced with increasing starch contents because of the increasement of hyrophilicity. Opacity of the starch-acrylic emulsion compound containing calcium carbonate was decreased with contents of starch by its intrinsic color. The film of starch-acrylic polymer showed more clear appearance with increasing starch contents owing to enhancement of amorphous state.

• Macromolecular Research
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• v.15 no.2
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• pp.173-177
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• 2007

Living anionic and cationic polymerizations have been combined to prepare various types of comb-like copolymers composed of polystyrene (PS) and polyisoprene (PI) blocks, with a precisely controlled architecture. According to the relative placement of these elementary building blocks, combs with randomly distributed PS and PI or with poly(styrene-b-isoprene) diblock branches (I & II, respectively) can be prepared. The reaction procedure initially includes the synthesis of a poly(chloroethylvinyl ether) using living cationic polymerization, which is used as the reactive backbone to successively graft $PS^-Li^+$ and $PI^-Li^+$ or $PI-b-PS^-Li^+$ to obtain structures (I) or (II). The synthesis of Janus-type PS-comb-b-PI-combs (III) initially involves the synthesis of a diblock backbone using living cationic polymerization, which bears two distinct reactive functions having either a protected or activated form. Living $PS^-Li^+$ and $PI^-Li^+$ are then grafted, in two separate steps, onto each of the reactive functions of the backbone, respectively.