• 멤브레인
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• 제18권4호
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• pp.282-293
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• 2008

친전자성 치환반응으로 제조된 술폰화 단량체, 비(非)술폰화 단량체 및 탄산칼륨을 이용하는 직접 중합법을 통하여 높은 점도의 술폰화 폴리아릴에테르술폰 공중합체를 합성하고, 이들을 원료로 N-메틸-2-피롤리돈(NMP)과 디메틸아세트아미드(DMAc)의 혼합 용매 상에서 직접 메탄을 연료전지용 고분자 전해질 막을 제조하였다. 막 제조 시의 용매 효과에 주목하여 혼합 용매의 부피 비는 $0{\sim}100%$로 변화시키고 공중합체의 술폰화도는 50%로 고정하였다. 이온 전도도 및 메탄올 투과도 측정을 통하여 최종 전해질 막의 기본 특성을 파악하고, 주사전자현미경 및 원자간력현미경분석을 통한 표면 분석 결과와 비교함으로써 이들의 상관관계를 고찰하였다. 막 제조 시의 용매 혼합 비율을 적절히 조절함에 따라 최종 전해질 막의 이온 전도도를 크게 향상시킬 수 있음이 확인되었는데, $25^{\circ}C$의 100% 가습 환경에서 측정된 수소 이온 전도도는 NMP : DMAc 50:50 부피/부피-%에서 최대 $1.38{\times}10^{-1}\;S/cm$이었다.

• Macromolecular Research
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• 제9권5호
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• pp.267-276
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• 2001

In order to endow with new bioactive functionality from demineralized bone particle (DBP) as natural source to poly(L-lactide) (PLA) synthetic biodegradable polymer, porous DBP/PLA as natural/synthetic composite scaffolds were prepared and compared by means of the emulsion freeze drying and solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. For the emulsion freeze drying method, it was observed that the pore size decreased in the order of 79$\mu\textrm{m}$ (PLA control) > 47$\mu\textrm{m}$ (20% of DBP) > 23 $\mu\textrm{m}$ (40% of DBP) > 15$\mu\textrm{m}$ (80% of DBP). Porosities as well as specific pore areas decreased with increasing the amount of DBR. It can be explained that DBP acts like emulsifier resulting in stabilizing water droplet in emulsion. For the solvent casting/salt leaching method, a uniform distribution of well interconnected pores from the surface to core region were observed the pore size of 80 ∼70 $\mu\textrm{m}$ independent with DBP amount. Porosities as well as specific pore areas also were almost same. For pore size distribution by the mercury intrusion porosimeter analysis between the two methods, the pore size distribution of the emulsion freeze drying method was broader than that of the solvent casting/salt leaching method due to the mechanism of emulsion formation. Scaffolds of PLA alone, DBP/PLA of 40 and 80%, and DBP powder were implanted on the back of athymic nude mouse to observe the effect of DBP on the induction of cells proliferation by hematoxylin and eosin staining for 8 weeks. It was observed that the effect of DBP/PLA scaffolds on bone induction are stronger than PLA scaffolds, even though the bone induction effect of DBP/PLA scaffold might be lowered than only DBP powder, that is to say, in the order of DBP only > DBP/PLA scaffolds of 40 and 80% DBP > PLA scaffolds only for osteoinduction activity. In conclusion, it seems that DBP plays an important role for bone induction in DBP/PLA scaffolds for the application of tissue engineering area.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.748-755
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• 2006

In this paper, a trade-off design and fabrication of IPMC(Ionic Polymer Metal Composites) as an actuator for a flapping device have been described. Experiments for the internal solvent loss of IPMCs have been conducted for various combinations of cation and solvent in order to find out the best combination of cation and solvent for minimal solvent loss and higher actuation force. From the experiments, it was found that IPMCs with heavy water as their solvent could operate longer. Relations between length/thickness and tip force of IPMCs were also quantitatively identified for the actuator design from the tip force measurement of 200, 400, 640, and $800{\mu}m$ thick IPMCs. All IPMCs thicker than $200{\mu}m$ were processed by casting $Nafion^{TM}$ solution. The shorter and thicker IPMCs tended to generate higher actuation force but lower actuation displacement. To improve surface conductivity and to minimize solvent evaporation due to electrically heated electrodes, gold was sputtered on both surfaces of the cast IPMCs by the Physical Vapor Deposition(PVD) process. For amplification of a short IPMC's small actuation displacement to a large flapping motion, a rack-and-pinion type hinge was used in the flapping device. An insect wing was attached to the IPMC flapping mechanism for its flapping test. In this test, the wing flapping device using the $800{\mu}m$ thick IPMC. could create around $10^{\circ}{\sim}85^{\circ}$ flapping angles and $0.5{\sim}15Hz$ flapping frequencies by applying $3{\sim|}4V$.

• 폴리머
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• 제38권4호
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• pp.464-470
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• 2014

A chemo-mechanical method was used to prepare lignin-containing cellulose nanofibrils(L-CNF) from unbleached woodpulps dispersed uniformly in an organic solvent. L-CNF/PLA composites were obtained by solvent casting method. The effects of L-CNF concentration on the composite performances were characterized by tensile test machine, contact angle machine, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The tensile test results indicated that the tensile strength and elongation-at-break increased by 50.6% and 31.8% compared with pure PLA. The contact angle of PLA composites decreased from $79.3^{\circ}$ to $68.9^{\circ}$. The FTIR analysis successfully showed that L-CNF had formed intermolecular hydrogen bonding with PLA matrix.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 추계 총회 및 학술발표회
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• pp.81-82
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• 1997

1. Introduction : The growth of membrane science was initiated by the invention of asymmetric membrane which can be formed by the technique known as phase inversion. The basic procedure of phase inversion involves casting a thin film of polymer solution onto a suitable substrate followed by immersion in a coagulation bath (quench step). Therefore, events occurring during the quench period, at which time solvent-nonsolvent exchange and eventual polymer precipitation take place, can play a controlling role in the determination of ultimate membrane structure.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.578-580
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• 2003

PEDOT [poly(3,4-ethylenedioxythiophene)] powder soluble in common organic solvent were synthesized by oxidative polymerization of EDOT (3,4-ethylene dioxythiophene) monomer using functional dopant, DEHSNa [sodium di(2-ethylhexyl)sulfosuccinate]. Transparent electrodes were made by spin casting of PEDOT/organic solvents on substrates. The electrode showed the transmittance < 90% in visible region and the surface resistance of> ${\sim}10^3\;ohm/{\square}$, respectively.

• 폴리머
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• 제34권3호
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• pp.210-214
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• 2010

트리아세틸 셀룰로오스(triacetyl cellulose, TAC) 용액필름 가공 시, 가공 공정 변수인 TAC 도프(dope)의 농도, 용매 제거 온도, 열처리 온도와 흐름특성 증가를 위하여 사용되는 가소제의 첨가가 TAC 필름의 구조 변형에 미치는 영향을 살펴보았다. 사용 도프의 농도가 높을수록, 용매 제거 온도가 높을수록 TAC의 결정화가 더 잘 발현됨을 알 수 있으며 이러한 결정화는 TAC 필름의 제조 후 열처리에 의하여 증가됨을 확인하였다. 또한, 가소제의 첨가에 의한 주사슬의 유연성 증가에 의하여 용융온도 및 결정화도가 감소하며 첨가된 가소제의 방향족 구조로 인하여 필름의 열분해 안정성이 우수해짐을 알 수 있었다.

• 한국주조공학회지
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• 제42권4호
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• pp.218-225
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• 2022

본 연구에서는 고압 다이캐스팅 (High pressure die-casting, HPDC)을 통해 알루미늄 합금 (상업코드: ALDC12종)으로 수소 자동차용 부품 (Air pressure control valve housing, APCVH)을 제조하였으며 주조품의 기밀성을 향상시키기 위해 유기 함침액을 개발하였다. 개발된 2종류의 유기 함침액 (INNO-series, 한국)과 상용 합침액 (P601, 일본)을 사용하여 함침공정 조건 및 후 처리에 따른 미세결함과 기밀성을 비교 평가하였다. 컴퓨터 단층촬영 및 3차원 X-선 현미경 분석을 통해 함침된 알루미늄 주조품의 결함제어 및 성능 개선을 확인하였다. 또한, 함침 공정 후 기밀성 시험에서 INNO-01이 함침된 시료의 경우 성능 개선율이 70%인 것으로 확인하였다. 따라서, 개발된 유기 함침액은 상용 가능하며 다이캐스팅 제품의 기밀성 향상에 도움이 될 것으로 판단된다.

• 대한의용생체공학회:의공학회지
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• 제25권1호
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• pp.1-4
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• 2004

조직공학은 생명과학, 의학, 공학의 기본개념 및 기술을 바탕으로 생체조직을 대체할 수 있는 인공조직 및 장기를 제작하여 이식함으로써 생체의 기능을 유지, 향상 또는 복원하는 것을 목표로 하는데 여기에 사용되는 기본 재료가 장기나 조직의 형태를 만들도록 돕는 scaffold이다. Scaffold를 만드는데 있어서 Solvent-casting과 Particulate leaching 기법은 다공성 폴리머 scaffold의 제조에서 널리 쓰이는 방법인데 여기 쓰이는 particle에는 소금과 젤라틴 둥이 사용되고 있다. 소금은 얻기가 쉽고 다루기에도 편리하다는 장점 때문에 가장 일반적으로 사용되고 있으며 젤라틴은 소금에 비하여 세포의 초기 접착과 증식에 유리하다는 이유로 최근에 많이 사용되고 있으나 이에 관한 비교실험은 아직 보고 된 바 없다. 본 연구에서는 소금과 젤라틴으로 만들어진 두 가지 scaffold를 비교해 보았으며 그 결과 젤라틴 scaffold가 초기상태의 세포 접합과 증식에 있어서 좋은 결과를 보였고 같은 공극율일 때 공극의 연결 상태가 훨씬 더 우수한 결과를 보였다.

• Macromolecular Research
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• 제11권5호
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• pp.334-340
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• 2003

In order to fabricate new sustained delivery device of nerve growth factor (NGF), we developed NGF-loaded biodegradable poly(L-lactide-co-glycolide) (PLGA, the mole ratio of lactide to glycolide 75:25, molecular weight: 83,000 and 43,000 g/mole, respectively) film by novel and simple sandwich solvent casting method for the possibility of the application of neural tissue engineering. PLGA was copolymerized by direct condensation reaction and the molecular weight was controlled by reaction time. Released behavior of NGF from NGF-loaded films was characterized by enzyme linked immunosorbent assay (ELISA) and degradation characteristics were observed by scanning electron microscopy (SEM) and gel permeation chromatography (GPC). The bioactivity of released NGF was identified using a rat pheochromocytoma (PC-12) cell based bioassay. The release of NGF from the NGF-loaded PLGA films was prolonged over 35 days with zero-order rate of 0.5-0.8 ng NGF/day without initial burst and could be controlled by the variations of molecular weight and NGF loading amount. After 7 days NGF released in phosphate buffered saline and PC-12 cell cultured on the NGF-loaded PLGA film for 3 days. The released NGF stimulated neurite sprouting in cultured PC-12 cells, that is to say, the remained NGF in the NGF/PLGA film at 37 $^{\circ}C$ for 7 days was still bioactive. This study suggested that NGF-loaded PLGA sandwich film is released the desired period in delivery system and useful neuronal growth culture as nerve contact guidance tube for the application of neural tissue engineering.