• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 춘계 총회 및 학술발표회
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• pp.50-51
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• 1995

The swelling behavior of hyddrogels has been interested in many applications of drug carriers. These gels show reversible swelling changes in response to pH, electric currcnt, and temperature. Among others, the temperature-responsive behavior of poly(N-isopropylacrylanxide) (p(NIPAAm)) was studied, because a lower critical solution temperature(LCST) is in the vicinity of 32$\circ$C, and remarkable temperature-response can be obtained. We propose a novel composite membrane, which is appropriate for transporting drug ingredients above the transition temperature. Our object was to design a high permeation system above the shrinking temperature of p(NIPAAm). The membrane was composed of a matrix polymer and thermosensitive p(NIPAAm) hydrogel. The flux pattern of 4-acctamidophen through membrane in response of temperature was opposite to that of p(NIPAAm) membrane.

• KSBB Journal
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• 제14권1호
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• pp.58-65
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• 1999

온도 및 pH에 동시에 민감한 하이드로젤 Poly(N-isopropy-lacrylamide-co-N,N'-dmerhylaminopropyl methacrylamide)을 합성하고, 그 팽윤 특성을 연구하였다. pH 민감성분인 N,N'-dmerhylaminopropyl methacrylamide (DMAPMAAn)의 물분율이 5%인 하이드로젤이 팽윤정도는 lower critucal solution temperature(LCST) 이상의 온도($37^{\circ}C$ 및 $40^{\circ}C$)에서 pH가 낮은 범위(pH 1-8)일 때 크게 증가하였다. 이는 온도민감성 하이드로젤이 같은 pH범위에서 전혀 팽윤이 일어나지 않는 것과 대조되었다. DMAPMAAm의 물분울이 20%인 경우에는 높은 pH(pH 12)에서도 젤이 상당히 팽창하였다. $40^{\circ}C$에서 pH가 12에서 2로 감소할 때 젤의 수분함량은 5mol%젤의 경우 38.8 wt%에서 84.7wt%로 증가하였고, 20mol%젤의 경우 60.6 wt%에서 90.8wt%로 증가하였다. 온도 및 pH에 동시에 민감한 하이드로젤의 부피 변화에 대해 이와 같이 pH는 온도 및 젤 조성의 영향을 받아 $37^{\circ}C$에서 pH 8보다 $40^\circC$에서 (pH 7) 더 낮아졌고, 5 mol%에서 (pH 7)보다 20 mol%일때 (pH 9) 증가하였다 LCST 이하의 온도 ($25^{\circ}C$)에서는 젤의 팽윤정도가 pH에 의해 크게 영향받지 않았다. 젤의 투명도와 LCST는 DMAPMAAm의 물분율에 따라 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1521-1525
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• 2009

Thermosensitive block copolymers of ethylene oxide and N-isopropylacrylamide (NIPAM) were synthesized. A five armed star shape oligo(ethylene oxide) initiator with a cyclotriphosphazene core was prepared and used for the atom transfer radical polymerization (ATRP) of NIPAM. The lower critical solution temperatures (LCSTs) of the copolymers were 36 to 46 ${^{\circ}C}$, higher than that of PNIPAM (32 ${^{\circ}C}$), depending on their molecular weights. The copolymers were soluble in water below the LCSTs but formed micelles above the LCSTs. The thermosensitive micellization behaviors of the polymers were investigated by fluorescence spectroscopy. With increasing the temperature of an aqueous solution of P2 and pyrene above the LCST, the peak of 333 nm red-shifted to appear around 339 nm and its intensity increased significantly, indicating the micelle formation. The transfer of pyrene into the micelles was also confirmed by a confocal laser scanning microscope. The fluorescence image obtained from P2 in an aqueous pyrene solution exhibited a green emission resulting from the pyrene transferred into the micelles. Salt effects on the solubility of the copolymers in an aqueous solution were investigated. The LCST of P2 decreased sharply as the concentration of sodium chloride increased, while decreased slowly with potassium chloride.

• 방사선산업학회지
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• 제6권4호
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• pp.317-322
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• 2012

In this study, the preparation of a temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted surface was performed using an eco-friendly and biocompatible ion beam-induced surface graft polymerization. The surface of a perfluoroalkoxy (PFA) film was activated by ion implantation and N-isopropylacrylamide (NIPAAm) was then graft polymerized selectively onto the activated regions of the PFA surfaces. Based on the results of the peroxide concentration and grafting degree measurements, the amount of the peroxide groups formed on the implanted surface was dependant on the fluence, which affected the grafting degree. The results of the FT-IR-ATR, XPS, and SEM confirmed that the NIPAAm was successfully grafted onto the implanted PFA. Moreover, the contact angle measurement at different temperatures revealed that the surface of the PNIPAAm-grafted PFA film was temperature-responsive.

• 폴리머
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• 제38권5호
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• pp.626-631
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• 2014

물을 정수하기 위해서는 그에 상응하는 막대한 양의 에너지가 소모되고, 이 때 소모되는 에너지는 환경오염을 야기할 수 있다. 이러한 문제 때문에 정수 공정 중에 상대적으로 낮은 에너지를 요구하는 정삼투 방법이 많은 관심을 받아왔다. 그러나 정삼투 방법은 오염수로부터 물을 끌어오기 위해서 높은 삼투압을 발생시킬 수 있는 유도용질이 필요하다는 점 때문에 어려움이 있었고 본 연구에서는 poly(N-isopropylacrylamide)(PNIPAM)이라는 온도 감응성 고분자 하이드로젤을 기본으로 하는 양쪽성 이온 물질과의 공중합체와 interpenetrating polymer network(IPN) 구조를 가지는 하이드로젤을 제작하고 이를 정삼투막에 부착시켜 성공적으로 유도용질 역할을 수행함을 확인하였다. 공중합체의 경우 팽윤비가 급격히 증가한 것을 확인할 수 있었으나, 그 만큼의 온도감응성이 떨어지는 모습을 보였고 IPN 구조의 경우는 온도감응성과 팽윤비 값이 PNIPAM 젤에 약간 못 미쳤다. 여기에 팽윤비 값과 삼투압의 관계를 확인하였다.

• KSBB Journal
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• 제15권6호
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• pp.548-555
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• 2000

온도 및 pH에 동시에 민감한 하이드로젤 poly(N-isopropy­l lacrylamide-co-N,N-dimethylaminopropy Imethacrylamide)을 온도 (13, 15.5, 18, 20.5 및 $23^{\circ}C$)와 pH (10.3, 11.3 및 12.3)를 달리 하여 합성하고 이 젤들의 외형, 기계적 강도, 젤 표면모양, LCST, 수축 pH 및 젤의 팽윤 특성을 연구하였다. 합성온도 및 합성 pH가 낮을수록 젤의 외형은 투명하였 고 기계적 강도는 높았다. SEM 관찰 결과 단백질 보다 더 큰 pore들 때문에 분리효율이 감소되는 것으로 사료된다. 합 성온도나 합성 pH의 증가는 LCST를 낮추었다. 외부온도가 LCST보다 낮은 $25^{\circ}C$ 에 서는 모든 합성온도와 합성 pH에 대 하여 젤은 전 pH에 걸쳐 팽윤된 상태에 있었다. $40^{\circ}C$에서는 LCST보다 높은 온도임에도 불구하고 poly (NIPAAm-co­D DMAPMAAm) 하이드로젤은 pH가 중성 및 산성 영역에서 팽윤되었다. 합성온도가 증가함에 따라 젤 부피가 가장 큰 폭으로 변하는 수축 pH가 더 높아졌다.

• 폴리머
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• 제35권3호
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• pp.223-227
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• 2011

자극감응성 고분자는 다양한 응용에 중요한 역할을 하는 재료로 널리 연구되어오고 있다. 온도감응성을 가지는 히알루론산 공중합체를 카르복실기 고분자와 생체친화성 히알루론산의 아미드 결합을 통하여 연결시켜 합성하였다. 온도감응성 특징은 두 공중합체 모두에 구현되었으며, 탁도 측정과 rheolgical 결과는 일치하였다. 두 공중합체 중 elastin-like peptide(ELP)를 그래프트 사슬에 둔 공중합체의 경우가 N-ispropylacryamide(PNIPAAm) 경우에 비해 보다 완만한 LCST 변화과정을 보여주었다. PNIPAAm과 ELP의 그래프트 부분 함량이 증가함에 따라 점도가 증가하였고, 비슷한 그래프트 함량에서는 PNIPAAm 공중합체의 점도 증가가 컸다. 이러한 결과를 통해 생체친화성의 히알루론산에 그래프트 사슬을 붙임으로써 온도감응성을 부여할 수 있고, 그 특성을 설계할 수 있음을 알 수 있었다.

• Carbon letters
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• 제13권3호
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• pp.173-177
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• 2012

A drug delivery system (DDS) was prepared with a temperature and pH-responsive hydrogel. Poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAAc)/poly(N-isopropylacrylamide) (PNIPAAm)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by radical polymerization for the temperature and pH-responsive hydrogels. MWCNTs were employed to improve both the thermal conductivity and mechanical properties of the PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels. Various amounts of MWCNTs (0, 0.5, 1 and 3 wt%) were added to the nanocomposite hydrogels. PVA/PAAc/PNIPAAm/MWCNT nanocomposite hydrogels were characterized with a scanning electron microscope. The mechanical properties were measured with a universal testing machine. Swelling and releasing properties of nanocomposite hydrogels were investigated at various temperatures and pHs. Temperature and pH-responsive release behavior was found to be dependent on the content of MWCNTs in nanocomposite hydrogels.

• 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.329-329
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• 2006

Various new active ester monomers based on (meth)acrylates and 4-vinylbenzoic acid have been prepared. Investigation of the controlled radical polymerization behavior of the respective monomers resulted in excellent polymerization control, thus, opening synthetic routes to reactive block copolymers. Polymer analogous reactions with amines yielded functional polymers. In the case of the copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate) a lower critical solution temperature could be measured at $52^{\circ}C$. Thus, the reactive copolymer features two characters: reactive AND stimuliresponsive behavior.