• Polymer(Korea)
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• v.28 no.4
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• pp.344-351
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• 2004

Poly(ethylene glycol)-based diblock and triblock polyester copolymers stimulating to temperature were studied as injectable biomaterials in drug delivery system because of their nontoxicity, biocompatibility and biodegradability. We synthesized the diblock copolymers consisting of methoxy poly(ethylene glycol) (MPEG) (M$_{n}$=750 g/mole) and poly($\varepsilon$-caprolactone) (PCL) by ring opening polymerization of $\varepsilon$-CL with MPEG as an initiator in the presence of HCl . Et$_2$O. The aqueous solution of synthesized diblock copolymers represented sol phase at room temperature and a sol to gel phase transition as the temperature increased from room temperature to body temperature. To confirm the in vivo gel formation, we observed the formation of gel in the mice body after injection of 20 wt% aqueous solution of each block copolymer. After 2 months, we observed the maintenance of gel without dispersion in mice. In this study, we synthesized diblock copolymers exhibiting sol-gel phase transition and confirmed the feasibility as biomaterials of injectable implantation.n.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.287-294
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• 2008

Molecularly imprinted polymer (MIPs) membranes were prepared by UV polymerization to separate racemates with opposite physiological activity, and then its separation selectivity of racemates was carried out. Likewise, their properties were examined. Polycarbonate (PC) membrane was polymerized as small spot form in pore inner wall, but anodisc (AD) membrane was polymerized as film form with thickness 500~700 nm onto the membrane surface. Also the study on the separation selectivity of prepared MIPs membranes was carried out in L-Tryptophane (Trp) racemate solution. The results showed that AD MIPs membrane polymerized as a film form, which was achieved by solution polymerizaion consisting of over 90% cross-linking agent (ethylene glycol dimethacrylate; EGDMA) and under 30% dispersing agent (methanol; MeOH), had predominant 3.5 selectivity.

• Polymer(Korea)
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• v.35 no.6
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• pp.543-547
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• 2011

A study has been done to enhance the mechanical properties and processability of electrically conductive polyaniline(PANI) without the polymer's structural alternation. Functionalized acid doped PANI (PANI-DBSA) was prepared by an emulsion polymerization, and dodecylbenzenesulfonic acid (DBSA) played both roles of surfactant and dopant. Also, PANI-DBSA was solution cast blended with high impact polystyrene (HIPS) to produce PANI-DBSA/HIPS blend film. The structure and electrical properties of the conducting polymer blends were observed through UV-vis and FTIR/ATR spectroscopy. A study of the blend was carried by focusing on observation of mechanical and electrical properties based on dispersibility and changes in polymer morphology. The conductivity of the blends was increased by increasing the content of PANI-DBSA, and the sudden increase of conductivity to $3.5{\times}10^{-4}$ S/cm was observed even under a low content of 9 wt%. There was a strong association of continuous network formation with percolation and conductivity in the conducting polymer blends.

• Membrane Journal
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• v.33 no.6
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• pp.383-389
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• 2023

A high-performance forward osmosis (FO) membrane was prepared using polyethylene glycol diacrylate (PEGDA) hydrogel as a support layer. Through the UV-induced polymerization and subsequent phase separation of PEGDA, the crosslinked, hydrophilic, and porous PEGDA suppor layer was obtained. To achieve high FO flux and salt selectivity using the fabricated PEGDA support, a selective layer was synthesized via the toluene-assisted interfacial polymerization (TIP), in which toluene is used as an organic solvent. The prepared PEGDA-based FO membrane showed higher FO water flux and lower salt selectivity compared with commercial HTI membranes using 1.0 M NaCl draw solution and DI water feed solution. We propose the strategy to fabricate high-performance FO membranes utilizing supports formed with new hydrophilic materials and fabrication processes.

• Korean Membrane Journal
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• v.9 no.1
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• pp.57-63
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• 2007

Amphiphilic graft copolymer from poly(vinylidene fluoride) (PVDF) was synthesized using atom transfer radical polymerization (ATRP) for composite nanofiltration membranes. Direct initiation of the secondary fluorinated site of PVDF facilitates grafting of tert-butyl methacrylate (tBMA). Amphiphilic PVDF-g-PMAA graft copolymer with a 51:49 wt ratio was obtained by hydrolyzing poly(tert-butyl methacrylate) (PtBMA) to poly(methacrylic acid) (PMAA). Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) confirmed the decrease of crystallinity of PVDF upon graft copolymerization. Composite nanofiltration membranes were prepared from PVDF-g-PMAA as a top layer coated onto PVDF ultrafiltration (UF) support membrane. The morphology and hydrophilicity of membranes were characterized using scanning electron microscopy (SEM) and contact angle measurement. The rejections of composite membranes were 80.2% for $Na_2SO_4$ and 28.4% for NaCl, and the solution flux were 9.5 and $14.5\;L/m^2\;h$ at 1.0 MPa pressure.

• Journal of the Korean Chemical Society
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• v.38 no.12
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• pp.885-890
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• 1994

Kinetics of electrochemical polymerization of aniline on a tungsten electrode in acidic aqueous solution was studied by means of cyclic voltammetry and kinetic measurements of anodic oxidation. Aniline molecule appeared to be intially oxidized via two-electron transfer to produce oxidized deprotonated aniline ion, which subsequently undergoes nucleophilic attack to the parent aniline and results in head to tail coupling to yield a dimerized species. But, being contrary to the case of Pt electrode, the propagation of polymerization occured through attack of the monomer by the oxidized aniline monomer to polymer. The growth rate of polyaniline was slow in comparison with the growth on Pt electrode. The degradation products were confirmed to be not p-benzoquinone(BQ) but p-phenylenediamine(p-PDA) by spectrophotometry, which agrees with the fact that oxidation of p-PDA was not observed below 1.0 V.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.406-414
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• 2010

A novel polyacrylamide grafted hydrous ferric oxide adsorbent composite has been synthesized by using glow discharge electrolysis plasma. To optimize the synthesis conditions, the following parameters were examined in detail: applied power, discharge time, post polymerization temperature, post polymerization time, amount of crosslinking agent and hydrous ferric oxide gel added and so on. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The removal percentage of the adsorbent in Pb(II) solution was examined and the data obtained showed that the adsorbent composite has a high capacity for lead ion. For the use in wastewater treatment, the thermodynamic and kinetic of Pb(II)-capture were also studied. Results indicated that the adsorption reaction was a spontaneous and an endothermic process, and it seems to be obeyed a pseudo-secondorder rate model. Moreover, the adsorption isotherm of Pb(II)-capture is following the Langmuir and Freundlich isotherm models.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.421-424
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• 2006

Nafion/Pt/Polypyrrole composite membranes were fabricated by chemical in-situ polymerization of pyrrole monomers with Pt precursors in Nafion matrix for DMFC. We demonstrated that positively charged pyrrolinum groups of polypyrrole particles were co-interacted with sulfonic groups of Nafion as verified by FT-IR results. Mutual interaction between $Nafion-SO_3^-$ (or negatively charged Pt precursors) and Polypyrrole$-NH_2^+$ influenced the physical properties of pristine Nafion. Thermal property proton conductivity, methanol permeability, and cell performance of pristine and modified Nafion were analyzed for an application of DMFC membrane. Thermal stabilities of sulfonic groups and side chains in Nafion/Pt/polypyrrole composite membranes were higher than those of Nafion due to mutual interaction between sulfonic groups of Nafion and pyrrolinum groups of polypyrrole. Methanol permeabilities of Nafion/Pt/Polypyrrole composite were reduced more proton conductivities with the increase in the content of Pt particles. As a result of that, the enhancement of cell performance by Nafion/Pt/Polypyrole O2 relative to Nafion was more pronounced under the specific experimental condition such as high temperature and more concentrated methanol solution.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.123-134
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• 1987

The transport phenomena of alkali metal chlorides through poly(2 hydroxyethyl methacrylate) hydrogel membrane have been studied using electrodialysis. The hydrogel membranes were prepared by the polymerization of 2-hydroxvethyl methacrylate in the presence of 45%(V/V) H2O and ethyleneglycodimethacrylate. The initiator used in the polymerization was azobismethylisobutyrate (AMIB) prepared from azobisiobtyronitrile (AIBN) using Mortimer method. The permeability of alkali metal chlorides such LiCl, NaCl and KCI at 50 voltage was obtained. The permeability of NaCl was also observed at 30, 40, 50, and 60 voltages respectively. The concentration of solutes permeated through the membrane was measurer by flame photometry. The experimental results have been discussed with the comparison of apparent solute molecular size, the self-diffusion coefficient of solutes, the transport number of cations in aqueous solution. These indic aloes that poly(2 hydroxyethyl methacrylate) hydrogel membrane shows a specific selectivity for sodium ion.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1825-1831
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• 2014

Grignard metathesis polymerizations of 1,1-disubstituted-2,5-dibromo-3,4-diphenylsiloles such as 1,1-dimethyl-2,5-dibromo-3,4-diphenylsilole, 1,1-diethyl-2,5-dibromo-3,4-diphenylsilole, 1,1-diisopropyl-2,5-dibromo-3,4-diphenylsilole, and 1,1-dihexyl-2,5-dibromo-3,4-diphenylsilole were performed to yield poly(1,1-disubstituted-3,4-diphenyl-2,5-silole)s containing fluorescent aromatic chromophore groups such as phenyl and silole in the polymer main chain: poly(1,1-dimethyl-3,4-diphenyl-2,5-silole), poly(1,1-diethyl-3,4-diphenyl-2,5-silole), poly(1,1-diisopropyl-3,4-diphenyl-2,5-silole), and poly(1,1-dihexyl-3,4-diphenyl-2,5-silole), respectively. The obtained materials are highly soluble in common organic solvents such as chloroform and tetrahydrofuran. Fourier-transform infrared spectra of all the polymers have characteristic C=C stretching frequencies at $1620-1628cm^{-1}$. The prepared organosilicon polymers exhibit strong absorption maximum peaks at 273-293 nm in the tetrahydrofuran solution, showing a red-shift of 18-34 nm relative to those of the monomer, strong excitation maximum peaks at 276-303 nm, and strong fluorescence emission maximum bands at 350-440 nm. Thermogravimetric analysis shows that most of the polymers are stable up to $200^{\circ}C$ with a weight loss of 6-16% in nitrogen.