• 한국재료학회지
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• 제22권6호
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• pp.275-279
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• 2012

(3-mercaptopropyl)trimethoxysilane (MPTMS) was used as a silylation agent, and modified silica nanoparticles were prepared by solution polymerization. 2.0 g of silica nanoparticles, 150 ml of toluene, and 20 ml of MPTMS were put into a 300 ml flask, and these mixtures were dispersed with ultrasonic vibration for 60 min. 0.2 g of hydroquinone as an inhibitor and 1 to 2 drops of 2,6-dimethylpyridine as a catalyst were added into the mixture. The mixture was then stirred with a magnetic stirrer for 8 hrs. at room temperature. After the reaction, the mixture was centrifuged for 1 hr. at 6000rpm. After precipitation, 150 ml of ethanol was added, and ultrasonic vibration was applied for 30 min. After the ultrasonic vibration, centrifugation was carried out again for 1 hr. at 6000rpm. Organo-modification of silica nanoparticles with a ${\gamma}$-methacryloxypropyl functional group was successfully achieved by solution polymerization in the ethanol solution. The characteristics of the ${\gamma}$-mercaptopropyl modified silica nanoparticles (MPSN) were examined using X-ray photoelectron spectroscopy (XPS, THERMO VG SCIENTIFIC, MultiLab 2000), a laser scattering system (LSS, TOPCON Co., GLS-1000), Fourier transform infrared spectroscopy (FTIR, JASCO INTERNATIONL CO., FT/IR-4200), scanning electron microscopy (SEM, HITACHI, S-2400), an elemental analysis (EA, Elementar, Vario macro/micro) and a thermogravimetric analysis (TGA, Perkin Elmer, TGA 7, Pyris 1). From the analysis results, the content of the methacryloxypropyl group was 0.98 mmol/g and the conversion rate of acrylamide monomer was 93%. SEM analysis results showed that the organo-modification of ultra-fine particles effectively prevented their agglomeration and improved their dispensability.

• 한국염색가공학회지
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• 제8권2호
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• pp.1-7
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• 1996

Thermotropic liquid-crystalline polyurethanes were synthesized by the polyaddition reaction of such para-substiuted diisocyanate monomer as 1,4-phenylene diisocyanate(1,4-PDI) and 2,5-tolylene diisocyanate(2,5-TDI), with 4,4'-bis($\omega$-hydroxyalkoxy)biphenyls(BPm: $HOC_{m}OC_{6}H_{4}C_{6}H_{4}OC_{m}H_{2m}OH$; m is the carbon number of the hydroxyalkoxy group). These polyurethanes have mesogenic biphenyl units in the main chain. Properties of polymers were studied by differential scanning calorimetry, wide-angle X-ray scattering, thermogravimetic analysis, polarizing microscopy, and infraed spectroscopy. DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. Mesomorphic behavior of the polyurethanes were also observed under the polarizing microscope. For example, polyurethane 2,5-YDI/BP5 with [$\theta$]=0.44 prepared from 2,5-TDI and BP5 exhibited a liquid crystalline phase from 194 to 205$^{\circ}C$. Infrared spectrum study indicated that the hydrogen bonding between urethane linkages affected the mesomorphism. The thermostabilities of polyurethanes 2,5-TDI/BP5 and 1,4-PDI/BP5 were measured at a heating rate of 1$0^{\circ}C$/min in air. The temperatures of 5% weight loss for 2,5-TDI/BP5 and 1,4-PDI/BP5 were 297 and 334$^{\circ}C$, respectively.

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.952-959
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• 2007

His-His-Leu (HHL), a tripeptide derived from a Korean soybean paste, is an angiotensin-I-converting enzyme (ACE) inhibitor. We report here a method of producing this tripeptide efficiently by expressing tandem multimers of the codons encoding the peptide in E. coli and purifying the HHL after hydrolysis of the peptide multimers. The HHL gene, tandemly multimerized to a 40-mer, was ligated with ubiquitin as a fusion gene (UH40). UH40 was inserted into vector pET29b; the UH40 fusion protein was then produced in E. coli BL21. The recombinant UH40 protein was purified by cation-exchange chromatography with a yield of 17.3mg/l and analyzed by matrixassisted laser desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry and protein N-terminal sequencing. Leucine aminopeptidase was used to cleave a 405-Da HHL monomer from the UH40 fusion protein and the peptide was purified using reverse-phase high-performance liquid chromatography (HPLC) on a C18 HPLC column, with a final yield of 6.2mg/l. The resulting peptide was confirmed to be HHL with the aid of MALDI-TOF mass spectrometry, glutamine-TOF mass spectrometry, N-terminal sequencing, and measurement of ACE inhibiting activity. These results suggest that our production method is useful for obtaining a large quantity of recombinant HHL for functional antihypertensive peptide studies.

• Macromolecular Research
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• 제14권2호
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• pp.173-178
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• 2006

Poly(3-(2-hydroxyethyl)thiophene) (P3HET) was synthesized using oxidative coupling polymerization that involved the protecting and deprotecting of hydroxyl groups but not the chlorine substitution or oxidative decomposition of the hydroxyl groups. The resulting P3HET exhibited good solubility in aprotic solvents, in contrast to the insoluble polymer product synthesized directly from the monomer, 3-(2-hydroxyethyl)thiophene (3HET). P3HET had low conductivity due to the strong hydrogen bonding of its hydroxyl groups. The ester-functionalized poly(3-(2-acetoxyethyl)thiophene) and poly(3-(4-pentylbenzoateethyl)thiophene) were also prepared with reasonably high molecular weights in order to examine how this functionalization modified the physical and chemical properties of P3HET. These polymers exhibited better solubility in common solvents and higher conductivity than P3HET. All these polymers exhibited bathochromic shifts of their film state absorption maxima with respect to those found in the UV-visible spectra of their solution phases. The extent of the bathochromic shift was found to vary with the lengths of the side chains of the ester-functionalized polymers.

• 한국응용과학기술학회지
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• 제22권4호
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• pp.362-370
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• 2005

Copolymers (HSA-98-20, HSA-98-0, HSA-98+20) which are acrylic resin containing 80% solid content were synthesized by the reaction of monomers, including methyl methacrylate, n-butyl acrylate, and 2-hydroxyethyl acrylate with a functional monomer, such as acetoacetoxyethyl methacrylate (AAEM), which may improve in cross-linking density and physical properties of films. The physical properties of prepared acrylic resins, containing AAEM, are as follows : viscosity, $1420{\sim}5760cps$ ; number average molecular weight, $2080{\sim}2300$ ; polydispersity index, $2.07{\sim}2.19$ ; conversions, $88{\sim}93%$, respectively. To prepare acryl resins, four kinds of initiators including ${\alpha},{\alpha}'-azobisisobutyronitirile$ (AIBN), di-tert-butyl peroxide (DTBP), t-amylperoxy-2-ethyl hexanoate (APEH), benzoyl peroxide (BPO) were used. The viscosity of the acrylic resins prepared with these initiators was increased in the order of DTBP>APEH>AIBN>BPO. APEH was proved as a suitable initiator in this study. Shear rates of acrylic resins were constant in respect to viscosity. From these results, it would appear that the resins have Newtonian flow characteristics and good workability.

• 공업화학
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• 제3권4호
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• pp.678-685
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• 1992

기능성 단량체가 점착물성에 미치는 영향을 알아보기 위하여 아크릴산과 기타 단량체로 아크릴 수지를 라디칼 용액중합을 이용하여 4원공중합시킨 후 물성을 측정하였으며, 또한 최적 점착 물성을 얻기 위하여 통계적 분석 방법을 이용하여 검토하였다. 점착물성에 있어서 아크릴산이 아크릴아미드보다 점착력의 증가에 미치는 영향이 컸다. 반면에 tackiness의 감소에 있어서는 아크릴아미드의 영향이 아크릴산 보다 컸다. 통계적 방법을 인용하여 점착물성 중 점착력, tackiness 그리고 응집력을 최적화 시킨 결과 단량체의 성분 비율은 부틸 아크릴레이트 81.7 mole%, 아크릴산 8.0 mole%, 아크릴아미드 2.1 mole%, 비닐아세테이트 8.2 mole% 일 때로 나타났고 이 때의 추정 회귀식은 다음과 같았다. $D=.857+.072X_1-.114X_2-.027X_3-.126X_1{^2}-.046X_1{\cdot}X_2-.063X_1{\cdot}X_3-.152X_2{^2}+.027X2{\cdot}X_3-.120X_3{^2}$ $X_1$:coded acylic acid, $X_2$:coded acylamide, $X_3$:coded vinylacetate

• 청정기술
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• 제23권2호
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• pp.148-157
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• 2017

To prepare UV-curable polyurethane-acrylate oligomer, NCO-terminated urethane prepolymers with trimethylolpropane, [TMP; 0 (0), 0.1 (0.021) and 0.2 (0.043) mole (mole fraction)] as crosslinkable tri-functional chain extender were end-capped with pentaerythritol triacrylate [PETA; 2.0 (0.400), 1.7 (0.354) and 1.4 (0.304) mole (mole fraction)] with one hydroxyl group/three vinyl functionalities. The stable as-formulated UV-curable polyurethane-acrylates [stable mixtures of PETA-capped oligomer/reactive acrylic monomer diluents without/with heptadecafluorodecyl methacrylate (PFA; 0, 6 and 9 wt%)] were formed up to 0.2 (0.043) mole (mole fraction) of TMP content in the prepolymer, while homogeneous-mixing failed at 0.3 (0.068) mole (mole fraction), in which the crosslink density in NCO-terminated urethane prepolymer was too high to enable the formation of stable mixture. This study examined the effect of TMP/PETA molar ratio and heptadecafluorodecyl methacrylate (PFA) content (wt%) on the properties of UV-cured polyurethane-acrylates as marine antifouling coating materials. The properties of UV-cured polyurethane-acrylate were found to be significantly dependent on the crosslinkable TMP/PETA ratio and PFA content. With the increasing of the TMP and PFA contents, the contact angles increased, and consequently the surface tension decreased. The adhesion of algae/barnacles to PFA contained film samples were found to be sufficiently weak to allow their easy removal. These results suggest that the UV-cured samples containing PFA have strong potential as coating materials for antifouling applications.

• 접착 및 계면
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• 제9권1호
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• pp.22-27
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• 2008

아크릴 점착제의 점착력을 목표 수준으로 향상시키기 위해 실험계획법을 이용하여, 2-ethyl hexyl acrylate (2-EHA), ethyl acrylate (EA), metha acrylic acid (MAA), acryl amide (AAm)를 라디칼 용액 중합하여 점착력을 측정하였다. 실험계획법은 반응표면분석법의 하나인 혼합물 설계를 이용하여 특수 3차 모형으로 분석하였으며, 그 적용은 상용프로그램인 MINITAB을 사용하였다. 수립된 실험계획에 의해 실험하고 분석한 결과, 목표하는 점착력을 얻기 위한 단량체 조성은 2-EHA (0.8861), EA (0.0639), MAA (0.03), AAm (0.02)로 나타났으며, 그 회귀분석 식은 다음과 같았다. $$y=54.8816x_1+80.7067x_2-44.4700x_3-99.0288x_1x_2+60.7706x_1x_3-441.030x_2x_3+974.341x_1x_2x_3$$.

• 접착 및 계면
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• 제13권1호
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• pp.1-8
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• 2012

EPDM에 카르복시산을 포함하는 아크릴 단량체인 methacrylic acid (MA)가 도입된 grafted EPDM을 합성하여 MA의 grafting ratio가 탄성체의 물성과 다른 고무와의 접착특성에 미치는 영향을 연구하였다. Grafted EPDM의 storage modulus는 특정온도까지는 sulfur로 가교한 EPDM vulcanizate보다 높게 유지되다가 온도가 더 높아지면 2차 결합력이 약해지면서 급격하게 감소되는 것이 관찰되었다. EPDM에 수소결합을 유도할 수 있는 반응기를 도입했을 때 grafted EPDM 분자들 간의 aggregate 형성과 그라프트된 MA의 결정성으로 인해 우수한 기계적 물성을 나타내었다. EPDM 자체는 극성이 낮고 다른 종류의 고무와 분자간 결합력이 약해서 접착이 제대로 이루어지지 않았으며 그라프트된 MA의 함량이 증가할수록 접착강도가 더 높아졌으며 MA의 grafting ratio가 10% 이상일 때에는 접착평가 시 고무시편이 부분적으로 파괴될 정도로 접착력이 우수하였다.

• 한국진공학회지
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• 제6권3호
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• pp.213-219
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• 1997

본 연구에서는 내전극 정전결합 유동가스형 반응장치를 이용하여 플라즈마 중합 스 티렌 박막을 제작하고 적외선분광스펙트럼, 열분해가tm크로마토그래피, 시차주사열량계 및 겔투과성 크로마토그래피의 분석을 통하여 중합조건이 분자구조 및 분자량 분포에 미치는 영향을 조사하였다. 위의 결과로부터 개시 모노머의 화학적 특성과는 다른 고도로 가교된 박막이 생성되었으며, 방전압력, 방전전력 및 가스의 유량 등의 중합조건 조절에 의해 분자 구조, 가교도, 분자량 분포 등의 제어가 가능함이 판명되었다. 따라서 내전극 정전결합 유동 가스형 반응장치에 의해 수행된 플라즈마중합법은 중합조건의 조절에 의해 센서의 감지막, 광도전성 소자 및 포토 레지스트 등에 응용가능한 기능성 유기박막의 제작에 좋은 특성을 나타내는 것을 알 수 있었다.