• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1993년도 제1회 추계심포지움 and 제2회 생리분자과학연구센터워크숍
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• pp.21-24
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• 1993

Many attempts have been made to use hydrogel as del ivory systems for various drug and vioactive materials to prolong and control their pharmacological activities. Rectal administration of drugs by using hydrogel bases, such as poloxamer ABA block copolymer (Pluronic F-127) gels, polyacrylic acid (Carbomer 934, 940, or 941) aqueous gels, and polyvilyl alcohol gels, have been reported on the preparation and potential suppository use of new gels(Eudragit L, Eudragit S, and Eudispert) that are block copolymers of methacrylic acid and methyl methacrylate. If) These hydrogel and xerogel preparations, especially Eudispert hv gels, show excellent staying and bioadhesive effects in the lower part of the rectum in rats and rabbits compared with those of polyethylene glycol (PEG)2000 and Witepsol H-15(or S-55) suppositories. Visual and optical microscopic observation of rectal membrances indicated no irritation or abnormality after administration of Eudispert hv tydrogel and xerogel.

• 한국막학회:학술대회논문집
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• 한국막학회 1996년도 춘계 총회 및 학술발표회
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• pp.60-61
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• 1996

Polyanion-polycation complexes had been known for a long time on an empirical basis fromthe mutual precipitation of proteins, before Kossel at the end of the previous century recognized the electrostatic nature of the interaction between oppositely charged polyions. The formation of polyelectmlyte complexes is essentially a result of the electrostatic nature of the interaction between oppositely charged polyions. This interaction in the macroscopic homogeneous system the phase transition by polysalt precipitation as well as the chemical and physical structure of polyelectrolyte complex membranes have been intensively investigated from the themodynamical and kinetical point of view.

• 한국응용과학기술학회지
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• 제33권3호
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• pp.421-427
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• 2016

Nanosized hollow silica was prepared by $St{\ddot{o}}ber$ method in the presence of aluminum isopropoxide. The mixture of polyelectrolytes such as poly(sodium 4-styrene sulfonate)(PSS) and polyacrylic acid(PAA) were used as templates. Tetraethylorthosilicate(TEOS) and aluminum isopropoxide were used as precursors for silica and alumina, respectively. The function of aluminum isopropoxide is to increase the porosity of silica shell. The characterizations of hollow silica were examined by TEM(transmission electron microscopy), TGA(thermogravimetric analysis), BET(Brunauer Emmett Teller), Energy-dispersive X-ray spectroscopy(EDS), and FT-IR spectrum. It was found that the shell thickness of hollow silica was around 8 nm and the core diameter was around 20 nm by TEM.

• 한국세라믹학회지
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• 제12권4호
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• pp.9-18
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• 1975

Polymer emulsion was used as the admixture for the purpose of increasing the mechanical properties of cement mortar. The effect of polymer emulsion admixture on compressive strength and tensile strength and chemical resistance, relative humidity on compressive and tensile strength, sand particles on water absorption were studied. The results were as follows. 1. Polymer emulson modified mortar cured under 95% of realative humidity showed lower strength than the mortar cured at dry condition. 2. The maximum strength was attained at 10~20% of polystyrene and polyacrylic acid ester polymer-cement mortar. 3. The modified mortar (sand size rate (-9＋35)mech:(-35＋60)mech=4 : 1) was 1.5 times lower than the modified mortar (1 : 1) in water absorption. 4. Compared with the ordinary mortar, the modified mortar showed 2~3 times greater chemical resistance for 5% HCl or 5% H2SO4.

• 한국세라믹학회지
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• 제30권10호
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• pp.838-844
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• 1993

To control the pore size of silcia gel, formamide (FA), N,N-dimethyl formamide (DMF), polyethylene glycol (PEG) and polyacrylic acid (PAA) were added in the sol-gel process from starting solution with tetramethyl orthosilicate (TMOS). The gels were characterized using porosimeter, TG-DTA and SEM. As a result, the more contents of FA and PAA was increased the more gelation time was decreased, also the more contents of DMF and PEG was increased the more gelling time was increased. The mean pore size of gels was larger in the order of PAA, DMF, FA and PEG. And the mean pore size of porous silica glass was 59.0$\AA$, 31.5$\AA$, 29.9$\AA$ and 29.0$\AA$, respectively, heated at 75$0^{\circ}C$/100$0^{\circ}C$.

• Restorative Dentistry and Endodontics
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• 제42권4호
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• pp.324-331
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• 2017

Objectives: This study evaluated smear layer removal by different chemical solutions used with or without ultrasonic activation after post preparation. Materials and Methods: Forty-five extracted uniradicular human mandibular premolars with single canals were treated endodontically. The cervical and middle thirds of the fillings were then removed, and the specimens were divided into 9 groups: G1, saline solution (NaCl); G2, 2.5% sodium hypochlorite (NaOCl); G3, 2% chlorhexidine (CHX); G4, 11.5% polyacrylic acid (PAA); G5, 17% ethylenediaminetetraacetic acid (EDTA). For the groups 6, 7, 8, and 9, the same solutions used in the groups 2, 3, 4, and 5 were used, respectively, but activated with ultrasonic activation. Afterwards, the roots were analyzed by a score considering the images obtained from a scanning electron microscope. Results: EDTA achieved the best performance compared with the other solutions evaluated regardless of the irrigation method (p < 0.05). Conclusions: Ultrasonic activation did not significantly influence smear layer removal.

• Journal of Pharmaceutical Investigation
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• 제31권3호
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• pp.173-180
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• 2001

The physicochemical characteristics such as glass transition temperature (Tg), surface energy, swelling and FT-IR of [P(AA-co-PEGMM)], a copolymer of acrylic acid (AA) and polyethyleneglycol monoethylether mono methacrylate (PEGMM), were evaluated. The Tg of [P(AA-co-PEGMM)] decreased with increasing PEGMM content. [P(AA-co-PEGMM)] with 18 mole% PEGMM had the Tg of about $40^{\circ}C$, the similar physiological temperature of human. Moreover, [P(AA-co-PEGMM)] with lower PEGMM content had higher hydration and expected lower mucoadhesive strengths. To predict the mucoadhesiveness of [P(AA-co-PEGMM)] films, the contact angle of films were measured. With the increasing content of PEGMM of films, the contact angle was increased and the higher mucoadhesive forces was expected. ATR-FTIR studies revealed that the addition of the PEG moiety in AA increased the potential of hydrogen bonding for [P(AA-co-PEGMM)] as compared to cross linking polyacrylic acid (cr-PAA) because the oxygen in the repeat unit of PEG contributed in the formation of hydrogen bonding in the presence of mucin solution.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.397-402
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• 2007

Restenosis after percutaneous coronary intervention (PCI) continues to be a serious problem in clinical cardiology. To solve this problem, drug eluting stents (DES) with antiproliferative agents have been developed. Variable local drug delivery systems in the context of stenting require the development of stent manufacture, drug pharmacology and coating technology. We have worked on a system that integrates electrophoretic deposition (EPD) technology with the polymeric nanoparticles in DES for local drug delivery and a controlled release system. The surface morphology and drug loading amount of DES by EPD have been investigated under different operational conditions, such as operation time, voltage and the composition of media. We prepared poly-D,L-lactide-co-glycolic acid (PLGA) nanoparticles embedded with curcumin, which was done by a modified spontaneous emulsification method and used polyacrylic acid (PAA) as a surfactant because its carboxylic group contribute negative charge to the surface of CPNPs (?53.5 ± 5.8 mV). In the process of ‘trial and error' endeavors, we found that it is easy to control the drug loading amount deposited onto the stent while keeping uniform surface morphology. Accordingly, stent coating by EPD has a wide application to the modification of DES using various kinds of nanoparticles and drugs.

• 구강회복응용과학지
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• 제25권1호
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• pp.73-82
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• 2009

인산칼슘시멘트(calcium phosphate cement)는 우수한 생체친화성 및 골전도성을 가지고 있어 골이식재로 많이 사용되어 왔다. 인산칼슘시멘트의 중요한 물성 중 하나인 흐름성은 유변학적 성질을 측정하여 확인할 수 있지만, 인산칼슘시멘트의 유변학적 성질에 관한 연구는 많이 진행되어 있지 않다. 이 실험의 목적은 인산칼슘시멘트를 hydroxyprophyl methylcellulose (HPMC) 수용액 및 polyacrylic acid (PAA) 수용액과 각각 혼합하여 주사용 인산칼슘시멘트를 만들고, 각각의 용액의 농도(35%와 17.5%의 HPMC, 2%와 1%의 PAA)와 온도($25^{\circ}C$ and $37^{\circ}C$)가 유변학적 성질에 미치는 영향을 연구하기 위한 것이다. 실험에 사용된 인산칼슘시멘트는 dicalcium phosphate dihydrate (DCPD)이며 유변학적 성질은 자동화된 rheometer를 사용하여 측정하였다. 통계분석은 Mann-whitney test를 사용하였다. 높은 농도의 경화액과 혼합된 인산칼슘시멘트는 (35% HPMC와 2% PAA)는 낮은 농도의 경화액과 혼합된 인산칼슘시멘트 (17.5% HPMC와 1% PAA)보다 각각 유의성 있게 높은 점도를 보였다. HPMC 수용액과 혼합된 인산칼슘시멘트는 $37^{\circ}C$에서 $25^{\circ}C$보다 유의성 있게 높은 점도를 보였다. PAA 수용액과 혼합된 인산칼슘시멘트는 $37^{\circ}C$에서 $25^{\circ}C$보다 낮은 점도를 보였으나 통계적 유의성은 없었다. 또한 실험에 사용된 모든 종류의 인산칼슘시멘트는 의사가소성(pseudoplastic)을 보였다.

• Korean Chemical Engineering Research
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• 제58권1호
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• pp.142-149
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• 2020

본 연구에서는 인조흑연의 낮은 이론용량을 개선하기 위하여 음극소재로서 흑연/실리콘/피치 복합소재의 전기화학적 성능을 조사하였다. 구형의 인조 흑연 표면을 polyvinylpyrrolidone (PVP) 양친성 물질로 코팅한 후 실리카를 성장시켜 흑연/실리카 소재를 합성하였으며, 석유계 피치 코팅과 마그네슘 열 환원법을 통해 흑연/실리콘/피치 복합소재를 제조하였다. 흑연/실리콘/피치 복합소재의 전극은 poly(vinylidene fluoride) (PVDF), carboxymethyl cellulose (CMC), polyacrylic acid (PAA) 바인더에 따라 제조하였으며, 다양한 전해액과 첨가제를 이용하여 전지를 조립하였다. 흑연/실리콘/피치 복합소재는 X-ray diffraction (XRD), scanning electron microscope (SEM)와 thermogravimetric analyzer (TGA)를 통해 물리적 특성을 분석하였으며, 전기화학적 특성은 충 방전 사이클, 율속, 순환전압전류, 임피던스 테스트를 통해 조사하였다. 흑연/실리콘/피치 복합소재는 흑연 : 실리카 : 피치 = 1 : 4 : 8일 때 높은 사이클 안정성을 보였다. PAA 바인더를 사용하여 제조된 전극은 높은 용량과 안정성을 보였으며, EC:DMC:EMC 전해액을 사용하였을 때 719 mAh/g의 높은 초기 용량과 우수한 사이클 안정성 나타내었다. 또한 vinylene carbonate (VC) 첨가시에 2 C/0.1 C 일 때 77% 용량 유지율과 0.1 C/0.1 C 일 때 88% 용량 회복을 나타냄을 확인하였다.