• 접착 및 계면
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• 제17권3호
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• pp.89-95
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• 2016

유연한 식품포장필름에 사용되고 있는 드라이 라미네이션용 유성접착제를 대체하기 위해, 고분자 분산제를 사용하여 유화하는 방법으로 수성 감압점착제를 친환경적으로 설계하였다. 유화중합에서 널리 사용하는 저분자량의 계면활성제는 물성의 변수로 작용해 왔다. 본 연구에서는 먼저 용액중합으로 polymeric nano-dispersant (PND)를 제조하고, 이 PND 입자들의 분산제를 micelle seed로 이용하여 core-shell grafted acrylic 점착제를 합성하였다. 이때 입자의 바깥층(shell)과 입자내층(core)의 $T_g$를 달리하여 얇은 필름의 점착조건인 초기접착력과 유지력의 균형을 이루도록 설계하였다. 최적화된 시험군 합성 점착제의 물성을 국내외 제조사에서 개발된 연구시료들과 비교분석하여, 점착제로서의 물성을 검토하였다. 물성 비교 결과, 본 연구에서 설계 합성한 저분자량의 계면활성제를 대체 사용한 고분자 나노분산제 기반 core-shell 점착제가 연포장에 적합한 점착물성을 나타냄을 확인하였다.

• 폴리머
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• 제28권2호
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• pp.111-120
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• 2004

반복 단위마다 양전하를 띄고 있는 폴리(디알릴디메틸암모늄 클로라이드) (PDADMAC)와 음이온 계면활성제인 도데실 황산 소듐 (SDS)와의 상호작용을 광산란법, 탁도법 및 형광법을 이용하여 조사하였다. 0.3 M NaCl 수용액에서의 PDADMAC는 마치 좋은 용매에서 팽창되어 있는 중성 고분자처럼 존재하나, SDS를 첨가함에 따라 이들 사이의 상호작용은 두 개의 임계 응집 농도로써 기술할 수 있었다. 첫 번째, 사슬 내 임계 응집 농도에서는 하나의 고분자 사슬 내에서 SDS의 마이셀화 과정으로써 [SDS]/[DADMAC] 0.06 정도에서 일어나며, 이 복합체 크기는 오히려 마이셀 형성되기 직전에 최대 값을 나타내고, 마이셀이 형성된 후부터는 일부 고분자 사슬도 마이셀 형성에 참여하기 때문에 SDS 첨가에 따라 점차로 수축되기 시작하였다. 두 번째, 사슬간 임계 응집 농도는 탁도 법에 의해 [SDS]/[DADMAC] 0.5에서 측정되었고, 이 두 번째 임계 응집농도 이상에서는 많은 마이셀들로 장식된 고분자 사슬들 사이의 응집화에 의한 거대한 응집체가 형성된다.

• Macromolecular Research
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• 제11권1호
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• pp.2-8
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• 2003

The self-assembly of polymers can lead to supramolecular systems and is related to the their functions of material and life sciences. In this article, self-assembly of Langmuir-Blodgett (LB) films, polymer micelles, and polymeric nanoparticles, and their biomedical applications are described. LB surfaces with a well-ordered and layered structure adhered more cells including platelet, hepatocyte, and fibroblast than the cast surfaces with microphase-separated domains. Extensive morphologic changes were observed in LB surface-adhered cells compared to the cast films. Amphiphilic block copolymers, consisting of poly(${\gamma}$-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) [or poly(N-isopropylacrylamide) (PNIPAAm)] as the hydrophilic one, can self-assemble in water to form nanoparticles presumed to be composed of the hydrophilic shell and hydrophobic core. The release characteristics of hydrophobic drugs from these polymeric nanoparticles were dependent on the drug loading contents and chain length of the hydrophobic part of the copolymers. Achiral hydrophobic merocyanine dyes (MDs) were self-assembled in copolymeric nanoparticles, which provided a chiral microenvironment as red-shifted aggregates, and the circular dichroism (CD) of MD was induced in the self-assembled copolymeric nanoparticles.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.254-254
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• 2006

The sensitivity of plasmid DNA (pDNA) to S1 nuclease, an enzyme to cleave a single-strand DNA, was dramatically modulated through a supramolecular assembly (polyion complex micelle) with a synthetic block copolymer, poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL). The pDNA condensed in stoichiometric charge ratio was cleaved into 7 fragments each being 10/12, 9/12, 8/12, 6/12, 4/12, 3/12, and 2/12 of the original DNA length, on the other hand, the pDNA condensed in higher charge ratios (>4), were digested into non-specific manner. Condensation of the pDNA was investigated from two viewpoints that how does the rigid DNA molecules fold and condense and how does the condensation influence their biological activity.

• Carbon letters
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• 제11권2호
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• pp.96-101
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• 2010

Dispersion of the functionalized multiwalled nanotubes (MWNT) in the polyurethane (PU) matrix and DC conductivity of the MWNT/PU composites are investigated with the oxidation conditions, the kind of surfactants and their content. First, the most optimal surfactant type and its critical micelle concentration in the MWNT suspension are determined as a cationic surfactant, benzalkonium chloride (BKC) of 0.6 wt.% to the MWNT content from DEA and FESEM results. All the MWNT oxidized under several conditions are negatively charged and functionalized with carboxylic group, whereas the degree of damage is different from oxidation conditions. In addition, each MWNT/PU composite derived from several oxidation conditions shows different DC conductivity at a characteristic MWNT content. It is found that in order to enhance DC conductivity of the polymeric composites containing the oxidized MWNT the better dispersion of MWNT should be obtained by effective functionalities and surfactant adsorption with preserving the intrinsic geometry of pristine MWNT.

• 설비공학논문집
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• 제8권3호
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• pp.330-337
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• 1996

The effects of pump and temperature on drag reducing characteristics were investigated with a polymer(PAAM : Polyacrylamide) and three kinds of surfactants(CTAC, STAC, Habon-G) in fully developed turbulent pipe flows with various experimental parameters such as additive concentration(30~500ppm), pipe diameter(4.65mm, 10.85mm), Reynolds number($4{\times}10^4{\sim}10^5$) and working fluid temperature($20{\sim}80^{\circ}C$). The pump effect on PAAM was severe such that the drag reduction rates obtained with pump were decreased upto 30% as compared with those obtained with compressed air in 4.65mm test section. The temperature effect on PAAM was noticeably considerable, that is, the higher temperaute, the less drag reduction rate. On the other hand, no significant pump effect on the surfactants was observed. The drag reducing effectiveness of CTAC was totally lost in the temperature ragne of 60 to $80^{\circ}C$, whereas STAC and Habon-G kept their distinct drag reducing capability at a temperature of $80^{\circ}C$. This study clearly elucidated that for DHC application of drag reducing additives, the pump and temperature effects as well as additive concentration and pipe diameter should be carefully taken into consideration.

• 폴리머
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• 제33권6호
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• pp.515-519
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• 2009

생분해성 고분자인 poly((R)-3-hydroxy butyrate)와 poly(ethylene glycol)을 결합시켜 양친성 이중블록 공중합체를 형성하었고, 표적인자인 folate를 수식하여 특정 암세포에 표적화하도록 설계하였다. 이 공중합체는 수용액상에서 미셀을 이루며, DLS로 측정한 결과, 125~156 nm의 크기였고, 동결건조하여 SEM으로 관찰한 결과 구형임을 확인하였다. 여기에 소수성 약물인 griseofulvin을 사용하여, 35~56%의 봉입률을 나타내었다. 약물은 in vitro상에서 24시간 동안 지속적으로 방출되었다. 세포생존율을 측정하여, folate가 수식된 입자가 그렇지 않은 입자보다 약 10% 더 낮은 세포생존율을 보임으로써 표적지향 효과가 있다는 것을 알 수 있었다.

• Macromolecular Research
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• 제17권2호
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• pp.99-103
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• 2009

We evaluated the efficacy of pH-sensitive micelles, formed by methoxy poly(ethylene glycol)-b-poly($\beta$)-amino ester) (PEG-PAE), as carriers for paclitaxel (PIX), a drug currently used to treat various cancers. PTX was successful encapsulated by a film hydration method. Micelles encapsulated more than 70% of the PTX and the size of the PTX-encapsulated micelles (PTX-PM) was less than 150 nm. In vitro experiments indicated that the micelles were unstable below pH 6.5. After encapsulation of PTX within the micelles, dynamic light scattering (DLS) studies indicated that low pH had a similar demicellization effect. An in vitro release study indicated that PTX was slowly released at pH 7.4 (normal body conditions) but rapidly released under weakly acidic conditions (pH 6.0). We demonstrated the safety of micelles from in vitro cytotoxicity tests on HeLa cells and the in vivo anti-tumor activity of PTX-PM in B16F 10 tumor-bearing mice. We concluded that these pH-sensitive micelles have potential as carriers for anti-cancer drugs.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2005년도 추계학술대회 논문집
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• pp.89-92
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• 2005

A microcapsule for drug delivery was successfully produced by utilizing the flow-through droplet-based supramolecular self-assembly in a crossed microchannel network. The PS-b-PMMA block copolymer synthesized atom transfer radical polymerization (ATRP) was initially formed as microdroplets and after the evaporation process it turned to spherical capsule by polymer self-assembly of the micro domains. The characteristics were studied using various analysis methods.

• Asian-Australasian Journal of Animal Sciences
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• 제7권4호
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• pp.513-516
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• 1994

The effects of the prevention of micelle formation and bile acid reabsorption, by using cholestyramine (CHOLN), a bile acid binding polymer, on the plasma lipid of Single Comb White Leghorn male chicks given diets containing medium chain triacylglycerol (MCT) and long chain triacylglycerol (LCT) were investigated. Corn oil and glyceryl tricaprylate were used as LCT and MCT sources, respectively. Plasma HDL cholesterol was reduced by CHOLN in all treatments. Plasma LDL cholesterol was reduced by CHOLN in chicks given LCT diet but not in MCT diet which could be accounted to the reduced plasma total cholesterol in LCT diet with CHOLN. It is concluded that bile acid binding does not alter the cholesteremic effect of MCT in the plasma of chicks.