• Current Photovoltaic Research
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• 제3권3호
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• pp.71-74
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• 2015

Soluble polyaniline was synthesized by attaching titanium isoproxide ($Ti(OPr)_4$) to the amine group of the aniline. Approximately 1 to 1 molar ratio of aniline and $Ti(OPr)_4$ was mixed and polymerized with ammonium persulfate. The FTIR result showed clear difference between $TiO_2$-aniline composite ($TiO_2An$) and $TiO_2$-polyaniline composite ($TiO_2PAn$). Although the $TiO_2An$ had negligible UV-visible absorption, the $TiO_2PAn$ showed strong absorption in the UV-visible region. Photoluminescence (PL) peaks of $TiO_2An$ were shifted toward red with the reduction of the excitation energy, which could be due to the multiple emission centers. The luminescence peak shift stopped at 501 nm. The PL spectra of $TiO_2PAn$ exhibited three emission peaks at 2.88 eV (430 nm), 2.48 eV (501 nm) and 2.22 eV (558 nm). The new emission center (2.22 eV) was observed after polymerization. Field emission scanning electron microscope image showed crack-free composite film.

• Macromolecular Research
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• 제13권6호
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• pp.483-490
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• 2005

A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan ($_{k}C$), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for $_{k}C$­g-polymethacrylic acid ($_{k}C$-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of super absorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

• 폴리머
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• 제35권5호
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• pp.431-437
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• 2011

아크릴계 이중인산과 과황산암모늄을 개시제로 사용하여 고분자 코팅용액의 기반인 poly(acryloyl diphosphoric acid)(poly(ADP))를 70 $^{\circ}C$의 수용액에서 라디칼 중합반응으로 제조하였다. 제조된 고분자 코팅용액인 poly(ADP)는 salmonella typhimurium, pseudomonas aeruginosa, escherichia coli, 그리고 staphylococcus aureus에 대한 항균성을 보였으며, 또한, Asperigillus niger와 조류인플루엔자 바이러스인 H1N1 바이러스에 대해서도 좋은 항진균성을 보여주었다. 더욱이 면섬유에 제조된 코팅용액 poly(ADP)를 코팅시켰을 경우에 우수한 난연성을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3163-3172
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• 2010

In this work, a novel method to synthesis of an acrylic superabsorbent hydrogel was reported. In the two stage hydrogel synthesis, first copolymerization reaction of acrylonitrile (AN) and acrylamide (AM) monomers using ammonium persulfate (APS) as a free radical initiator was performed. In the second stage, the resulted copolymer was hydrolyzed to produce carboxamide and carboxylate groups followed by in situ crosslinking of the polyacrylonitrile chains. The results from FTIR spectroscopy and the dark red-yellow color change show that the copolymerization, alkaline hydrolysis and crosslinking reactions have been do take place. Scanning electron microscopy (SEM) verifies that the synthesized hydrogels have a porous structure. The results of Brunauer-Emmett-Teller (BET) analysis showed that the average pore diameter of the synthesized hydrogel was 13.9 nm. The synthetic parameters affecting on swelling capacity of the hydrogel, such as AM/AN weight ratio and hydrolysis time and temperature, were systematically optimized to achieve maximum swelling capacity (330 g/g). The swollen gel strength of the synthesized hydrogels was evaluated via viscoelastic measurements. The results indicated that superabsorbent polymers with high water absorbency were accompanied by low gel strength. The swelling of superabsorbent hydrogels was also measured in various solutions with pH values ranging from 1 to 13. Also, the pH reversibility and on-off switching behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents. Finally, the swelling of synthesized hydrogels with various particle sizes obey second order kinetics.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.927-933
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• 2011

Conducting polyaniline-poly($\varepsilon$-caprolactone) polymer composites were synthesized via in situ deposition techniques. By dissolving different weight percentages of poly($\varepsilon$-caprolactone) (PCL) (10%, 20%, 30%, 40%, and 50%), the oxidative polymerization of aniline was achieved using ammonium persulfate as an oxidant. FTIR, UV-vis spectra, and X-ray diffraction studies support a strong interaction between polyaniline (PANI) and PCL. Structural morphology of the PANI-PCL polymer composites was studied using scanned electron microscopy (SEM) and transmittance electron microscopy (TEM), and thermal stability was analyzed by thermogravimetric analysis (TGA) technique. The temperature-dependent DC conductivity of PANI-PCL polymer composite films was studied in the range of 305-475 K, which revealed a semiconducting behavior in the transport properties of the polymer films. Conductivity increased with the increase of PCL in below critical level, however conductivity of the polymer film was decreased with increase of PCL concentration higher than the critical value.

• 한국안전학회지
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• 제18권4호
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• pp.78-84
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• 2003

Core-shell composite particles of organic/organic were polymerized by using monomers such as methyl methacrylate(MMA) and styrene(St) in the presence of sodium dodecyl benzene sulfonate (SDBS) below critical micelle concentration(CMC) changing concentration, kind of initiators, emulsifiers, addition method of monomers and speed of agitation. In the PMMA/PSt and PSt/PMMA core-shell polymerization, to suppress the generation of new particles and to minimize the coagulation during the shell polymerization, the optimum conditions were $1.45{\times}10^{-5}mol/L$ and $2.91{\times}10^{-5}mol/L$ at concentration of SDBS respectively. The optimum concentration of the other initiator was $1.58{\times}10^{-3}mol/L$ of ammonium persulfate(APS) for core polymerization and $4.0{\times}10^{-4}mol/L$ of APS for shell polymerization.

• 폴리머
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• 제27권4호
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• pp.358-363
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• 2003

하이드록시프로필 셀룰로오스와 암모니움 퍼설페이트를 각각 입자 안정제와 개시제로 사용하여 에틸 알코올/물 혼합 분산매에서 아크릴아미드의 분산 중합을 다양한 중합 조건하에서 수행하여 생성되는 poly(acrylamide) (PAM) 라텍스의 평균 입자경, 라텍스 고분자의 점도 평균 분자량, 수용화 정도 등을 관찰하였다. 일반적으로 PAM 라텍스의 평균 입자경은 개시제의 농도, 분산매 중의 물의 농도, 중합 온도가 증가함에 따라 증가하였으나 단량체의 농도, 입자 안정제의 농도는 감소함에 따라 증가하였다. 라텍스 상태로 얻어진 PAM 고분자의 점도 평균 분자량은 단량체의 농도, 입자 안정제의 농도, 분산매 중 물의 농도가 증가함에 따라, 또는 개시제의 농도, 중합 온도가 감소함에 따라 증가하였다. 본 연구에서 얻어진 PAM 라텍스는 0.5~2.4 $\mu\textrm{m}$의 평균 입자경과 20000~335000g/㏖의 점도 평균 분자량을 나타내었으며 이들은 물중에 분산하였을 때 순간적으로 수용화되었다.

• 폴리머
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• 제34권1호
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• pp.38-44
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• 2010

탄산칼슘/유기계 core-shell 입자를 제조하기 위해 core로는 침강성 탄산칼습을 사용하였고, shell로서는 여러 종류의 methyl methacrylate(MMA), ethyl acrylate(EA), n-butyl acrylate(BA), styrene(St), 2-ethylhexyl acylate(2-EHA)을 사용하여, 반응 온도 유화제, 개시제의 종류와 첨가량을 변화시킨 후에 유화중합을 시켜 최적의 유화중합 조건을 구하였다. 생성된 core-shell 입자의 구조는 FT-IR로, 입자크기와 형태는 입도 분석, SEM, TEM으로 각각 측정하였다. 그리고, 이 core-shell 입자에 부직포를 함침시켜 처리전후의 표면변화는 접촉각으로 확인하였다. 또한, 함침 처리 전후의 부직포/부직포 소재와 관능성 단량체 첨가한 부직포/부직포 소재의 박리 접착강도를 측정하여 상호 비교하였다. 탄산칼슘/유기 core-shell 입자 합성의 경우에는 유화제인 SDBS를 0.5 wt% 첨가한 탄산칼슘을 core로 하여 MMA와 0.1 wt% 농도의 APS를 단계적으로 주입하여 중합함으로써 탄산칼슘입자 표면에 단량체의 중합이 잘 유도될 수 있었으며 중합 도중에 새로운 중합체 입자의 생성이 적었다.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.109-109
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• 2018

Bacillus subtilis B22, a chemotrophic and aerobic bacterial strain was isolated from homemade kimchi, identified by 16S rRNA gene sequencing. B22 was primarily screened by biochemical, carbon source utilization tests. B22 was used to produce pectinase and ${\beta}$-glucosidase by submerged fermentation under different light sources. B22 was incubated in pectin media and basal media (pH 7.0) under blue, green, red and white light-emitting diodes (LEDs), fluorescent white light, and in darkness at $37^{\circ}C$, orbital shaker 150 rpm for 24 hours. Fermentation under blue LEDs maximized pectinase production ($71.59{\pm}1.6U/mL$ at 24 h) and ${\beta}$-glucosidase production ($56.31{\pm}1.6U/mL$ at 24 h). Further, the production of enzyme increased to pectinase ($156{\pm}1.28U/mL$) and ${\beta}$-glucosidase ($172{\pm}1.28U/mL$) with 3% glucose as a carbon source. Activity and stability of the partially purified enzymes were higher at pH 6.0 to 8.0 and $25-55^{\circ}C$. The effect on the metal ions $Na^+$ and $K^+$ and (moderateactivity) $Mn^{2+}$ and $Ni^{2+}$ increased activity, while $Hg^{2+}$, $Cu^{2+}$, $Fe^{2+}$, and $Fe^{2+}$ inhibited activity. EDTA, phenylmethylsulfonyl fluoride and 5,5-dithiobis (2-nitrobenzoicacid) reduced activity, while tetrafluoroethylene and 1,10-phenanthroline inhibited activity. The amylase was highly tolerant of the surfactants TritonX-100, Tween-20, Tween-80 and compatible with organic solvents methanol, ethanol, isoamylalcohol, isopropanol, t-butylalcohol and the oxidizing agents hydrogen peroxide, sodium perborate and sodium hypochlorite, although potassium iodide and ammonium persulfate reduced activity. These properties suggest utility of pectinase and ${\beta}$-glucosidase produced by B. subtilis B22 under blue LED-mediated fermentation for industrial applications.

• Korean Chemical Engineering Research
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• 제47권4호
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• pp.470-475
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• 2009

본 연구에서는 유화중합을 이용한 수분산성 아크릴계접착제의 최적의 합성조건을 구하기 위하여 주단량체로 2-EHA(2-ethylhexyl acrylate), n-BA(n-butyl acrylate), MMA(methyl metacrylate), 기능성단량체로 2-HEMA(2-hydroxylethylmethacrylate), AAc(acrylic acid), 유화제로는 음이온성 유화제인 SLS(Sodium Lauryl Sulfate), 그리고 개시제로 APS(Ammonium persulfate)를 사용하여 전환율, 입자 크기, 박리강도, 유리전이온도에 대한 유화제, 개시제, 단량체 함량의 영향을 고찰하였다. 반응온도 $82^{\circ}C$, 유화제(SLS/monomer) 3.75%, 개시제(APS/monomer) 0.612%에서 95% 이상의 전환율을 얻을 수 있었고, 유화제나 개시제의 양이 너무 많을 때는 박리접착강도가 감소하는 경향을 보였으며, 65% 2-EHA/monomer, 20% BA/monomer, 10% MMA/monomer에서 최대 전환율과 최대 박리접착강도를 얻을 수 있었다.