Electrospun thermo-responsive nanofibers of poly(hydroxyethylacrylate-co-coumaryl acrylate-co-ethylmethacrylate)

Guo, H.,Jeong, J.H.,Kim, J.C. Elsevier 2016 Colloids and surfaces. A, Physicochemical and engi Vol.495 No.-

<P>Thermo-responsive nanofibers were prepared by electrospinning poly( hydroxylethylacrylate-cocoumaryl acrylate-co-ethylmethacrylate) (P(HEA-CA-EMA)) dissolved in methanol. P(HEA-CA-EMA)s were prepared by free radical reaction using the reaction mixture of which HEA/CA/EMA molar ratio was 98:0:2, 96:2:2, 95:2.5:2.5, 94:3:3, and 92:4:4. P(HEA-CA-EMA) solutions (30% (w/v), in HEPES buffer (30 mM, pH 7.4)) became gel after they were subjected to UV irradiation (254 nm, 6W) for 20h. P(HEA-CA-EMA) exhibited lower critical solution temperature (LCST) behavior in aqueous solution and the LCST decreased from about 40 degrees C to below 20 degrees C, when the content of hydrophobic monomers (CA and EMA) increased from 0.7% to 5.5%. By an electrospinning process, P(HEA-CA-EMA) solutions in methanol were micronized into beads when the copolymer concentration was relatively low (e.g., 30%), and they were spun into nanofibers when the concentration was 60-80%. The nanofibers were subjected to UV irradiation to cross-link the constituent copolymer chains. The release of CF (a hydrophilic dye) from UV-treated P(HEA-CA-EMA) nanofibers was suppressed below LCST and promoted above LCST. As long as the temperature of release medium was higher than LCST, the release degree at a given temperature was higher when the nanofiber was composed of a copolymer exhibiting lower LCST. As LCST decreases, the dehydration degree and the hydrophobicity of the copolymers at a given temperature will increase thus the thermodynamic activity of the hydrophilic dye in the nanofiber will also increase, giving a rise to a higher release degree. (C) 2016 Elsevier B.V. All rights reserved.</P>

pH/온도-동시 민감성 Hydrogel의 합성조건에 따른 특성 연구

유형덕,정인식,박창호 한국생물공학회 2000 KSBB Journal Vol.26 No.4

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. A hydrogel, poly(N-isopropylacrylamide-co-N, N-dimethylaminopropylmethacrylamide), sensitive to both pH and temperature, was synthesized and characterized at $^13∼23{\circ}C$ and pH of 10.3∼12.3. The gel was more transparent and mechanically stronger at lower preparation temperature and pH. Large pores observed in scanning electron microscope seem to be responsible for the lower biomolecular separation efficiency. The lower critical solution temperature (LCST) decreased at a higher polymerization temperature. At $25^{\circ}C$, which is lower than the LCST, the gel was swollen regardless of the solution pH. At $40^{\circ}C$, however, the gel was swollen at neutral and acidic pHs even though the temperature was higher than the LCST. The gel collapse pH, defined as the point at which the gel made its largest volume decrease per unit pH increment, increased as the gel preparation temperature increased.

Fabrication of Thermosensitive Microparticles for Controlled Drug Delivery

문주연,노윤호,김현웅,봉기완 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Controlled drug delivery is important for therapeutic efficacy. Among stimuli-responsive polymers, thermo-responsive polymers have drawn much attention because this stimulus occur in the body and can be given from outside, which makes it easier to control. Here, we introduce Poly(N-vinyl caprolactam)(PVCL) microparticles for controlled drug delivery. Unlike PNIPAm, PVCL has good biocompatibility. Microparticles were synthesized via Stop Flow Lithography technique. We verified that polymer network in microparticles are contracted above certain temperature known as lower critical solution temperature (LCST). After adjusting the LCST to body temperature by adding poly ethylene glycol 700 diacrylate as a hydrophilic component, we conducted drug release using Doxorubicin and revealed that the releasing rates were significantly higher at above LCST than below LCST. Moreover, we fabricated gold nanorod(GNR) incorporated PVCL microparticles to control drug release by exposure of near-infrared.

가역적 온도감응성을 가지는 가교된 나노운반체의 제조와 그 특성

이상봉 ( Sang Bong Lee ),심진기 ( Jin Kie Shim ),정석진 ( Suk Jin Chung ) 한국키틴키토산학회 2010 한국키틴키토산학회지 Vol.15 No.4

하한임계온도를 가지는 PNIPAAm과 Chitosan을 포함하는 공중합체로 이루어진 약물전달체는, 온도변화에 따라 가역적으로 입자의 형성 및 방출 거동을 보이므로, LCST 이하에서 약물전달체 입자를 형성 할 수 있을 뿐만 아니라 PNIPAAm의 분자길이 조절을 통해 약물 전달체 크기 또한 결정 할 수 있어 약물의 포집 및 방출이 용이한 효율적인 약물전달체로 이용될 수 있다. 개발된 약물전달체는 공중합 반응의 반응비를 제한함으로써 나노수준의 입자 크기를 가지므로, 생물의 원형질막을 통과할 수 있는 효과가 기대 된다. 또한 약물전달 체의 표면 가교를 통해 온도변화에 무관하게 입자상태를 유지할 수 있었으므로 약물 포집상태의 안정성을 효과적으로 높일 수 있었다. This study is about drug delivery system (DDS) using copolymer of hydrophilic and temperature sensitive polymer. The copolymer was maintained the particle form by crosslinking of the surface at temperature lower than lower critical solution temperature (LCST) and it has thermo-sensitivity on changing the size of the particle above LCST. The developed copolymer is obtained or loss the amphiphilic by changing temperature then it is possible to form of the reversible particle size. Thus it can be used as a nano-carrier for drug delivery system by collected drugs. In this study, the nano-carrier can do drug delivery even under LCST.

Synthesis and Characterization of Thermosensitive Poly(organophosphazenes) with Methoxy-Poly(ethylene glycol) and Alkylamines as Side Groups

Lee, Bae-Hoon,Lee, Young-Moo,Sohn, Yoon-Soo,Song, Soo-Chang Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.4

Thermosensitive poly(organophosphazenes) bearing methoxy-poly(ethylene glycol) (MPEG) and alkylamines as substituents have been synthesized and characterized by elemental analysis, NMR spectroscopy, GPC, and DSC. All the polymers exhibited crystallinity, which was probably induced by the MPEG side chain of the polymers. All the polymers exhibited the lower critical solution temperature (LCSTs) in the range of 28 to $94^{\circ}C$ depending on several factors such as mole ratio of the substituents, kinds of PEG and alkylamines. The higher content of MPEG and shorter chain length of alkylamines of the polymers afforded the higher LCST. The LCSTs of the polymers exhibited almost concentration-independent behavior in the range of 3-30 wt % of the polymers in aqueous solutions. The polymers showed the higher LCSTs in the acidic solutions than in the neutral and basic solutions. The ionic strength of the polymer solution affected the LCST, which decreased with increased NaCl concentration. The polymer bearing almost equimolar substitutuents with the -N-P-N- unit has shown the LCST more sensitive to NaCl and pH than that with the -N-P-O- unit. The polymers were found to degrade in acidic solution but be very stable in alkali solution as well as in the buffer solution of pH 7.4.

Preparation of Biodegradable Thermo-responsive Polyaspartamides with N-Isopropylamine Pendent Groups (I)

Jong-Rok Moon,Ji-Heung Kim* 대한화학회 2006 Bulletin of the Korean Chemical Society Vol.27 No.12

Novel amphiphilic, thermo-responsive polyaspartamides which showed both LCST (lower critical solution temperature), and sol-gel transition were prepared and characterized. The polyaspartamide derivatives were synthesized from polysuccinimide, the polycondensate of aspartic acid monomer, via successive nucleophilic ring-opening reaction by using dodecylamine and N-isopropylethylenediamine (NIPEDA). At the intermediate composition ranges, the dilute aqueous solution exhibited a thermally responsive phase separation due to the presence of LCST. The phase transition temperature was controllable by changing the content of pendent groups. In addition, a physical gelation, i.e. the sol-gel transition was observed from the concentrated solutions, which was elucidated by dynamic viscoelastic measurements. These novel injectable and thermo-responsive hydrogels have potential for various biomedical applications such as tissue engineering and current drug delivery system.

LCST 고분자-금 나노입자 복합체를 이용한 온도감응형 색센서 제조

손형진,문해주,김지수,김영훈 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

온도감응성 고분자는 가역적으로 수축·팽창하는 온도인 LSCT를 가지는 물질로, 그 중 PNIPAM은 체온에 근접한 온도 범위에서 LCST를 나타내 다양한 분야에서 활용된다. 이 고분자에 금 나노입자를 접합하면 나노입자의 LSPR효과로 인해 고분자가 수축·팽창할 때 색변화가 나타나며, 이를 통해 특정 범위의 온도를 감지할 수 있는 색센서로 활용할 수 있다. 본 연구에서는 라디칼 중합을 통해 PNIPAM을 하이드로겔 형태로 합성하였고, 금 나노입자를 하이드로겔 내부에서 환원시켜 색센서를 제작하였다. 센서에 온도 변화를 주었을 때, 붉은색에서 보라색으로의 색변화를 확인하였다. 하이드로겔의 물성을 다양하게 설정하여 센서의 성능을 비교하였다. 본 연구를 통해 온도 변화를 쉽게 파악할 수 있는 색센서 제작을 기대할 수 있다.

Synthesis of Thermo-responsive Hydrogel Based on N-Isopropylacrylamide with AIE-acitve Azonaphthol Derivatives

오민택,이택승 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Hydrogels are composed of hydrophilic polymer networks with chemical or physical crosslinks which provide their unique properties such as swelling, shrinkage in water. Especially, hydrogels based on Poly(N-isopropylacrylamide) exhibit a sol-gel transition at the lower critical solution temperature (LCST) which becomes hydrophobic and aggregated above the LCST. In this work, we synthesized PNIPAMbased hydrogels with AIE-active azo derivatives via emulsion polymerization. Aggregation induced emission (AIE)-based molecules increased emission in the solid state. We synthesized polymerizable AIEgen by introduction of vinyl group at the end of AIEgen for further use in radical polymerization. As a result, we expected fluorescence switching of AIE-active azonaphthol derivatives by sol-gel transition of synthesized hydrogels by temperature.

Atomistic molecular dynamics simulation of stimuli-responsive poly(2-dimethylaminoethyl methacrylate)

민사훈,김병수 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) is a stimuli-responsive polymer whose phase transition in solution is influenced by the temperature and the pH of solution. In this presentation, we report on our recent results of the all-atomistic molecular dynamics simulation for the coil-to-globule transition of PDMAEMA. In the structural analysis, a single chain of PDMAEMA shows the coil-to-globule transition in aqueous solution from below LCST to above LCST. The hydrogen bond and local dynamics of water molecules near the PDMAEMA chain provides atomic-level insights into the role of each functional group in PDMAEMA for the coil-to-globule transition.

Preparation and Properties of Controllable Thermo-responsive Hydrogel Materials For Smart Windows

장지원,심재학,김일진,박현호,천지원,이진홍,박종승,이동진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

The thermo-responsive polymer can be used as a material for smart window that can be control the solar light transmittance according to the external temperature because the phase transition occurs according to the temperature change. A thermo-responsive polymer has a reversible sol-gel phase at a certain temperature. The certain temperature at which phase transition occurs is called the LCST. In order to obtain a high performance smart window material, we used to the monomers N-isopropylacrylamide(NIPAm) and N-isopropylmethacrylamide (NIPMAm). In this study, we investigated the LCST, freezing point and solar light transmittance of the effect of Glycerol contents.