말단 아민가를 갖는 폴리(N-이소프로필아크릴아미드) 및 알긴산 나트륨-g-폴리(N-이소프로필아크릴아미드)의 합성과 열응답 특성

이은주(Eun Ju Lee),김영호(Young Ho Kim) 한국고분자학회 2013 폴리머 Vol.37 No.4

열응답성 고분자인 폴리(N-이소프로필아크릴아미드)(PNlPAAm) 말단에 아민기를 갖는 PNIPAAm-NH2 및 이들 알긴산 나트륨에 그래프팅시킨 공중합체를 합성하고 이들의 여러 가지 특성들을 분석하였다. PNIPAAm-NH2를 합성하기 위하여 N-이소프로필아크릴아미드를 라디칼 중합할 때 2-adminoethanethiol hydrochloride (AESH)를 연쇄이동제로 사용하였다. AESH 농도를 높이면 PNIPAAm-NH2의 분자량이 작아지며 PNIPAAm-NH2 수용액의 하한임계용액온도(LCST)가 낮아졌다. N-(3-dimethy laminopropyl)-N`-ethylcatbodiimide 및 N-hydroxysuccinimide를 사용하여 PNIPAAm-NH2를 graft-onto 방법으로 알긴산 나트륨에 그래프팅시킨 alginate-PNIPAAm 공중합체 역시 온도에 따라 팽윤-수축 거동을 하였으며, PNIPAAm-NH2보다 약간 높은 온도에서 LCST를 나타내었고, 그래프트된 PNIPAAm의 양이 많아질수록 팽윤비가 커졌다. Amino group-terminated poly(N-isopropylacrylaniide) (PNIPAAm-NH2) was synthesized via a radical poly-merization of N-isopropylacrylamide (NIPAAm) using 2-aminoethanethiol hydrochloride (AESH) as a chain transfer agent. The molecular weight of the PNIPAAm-NH2 was controlled by changing the concentration of AESH. The LCST of the aqueous solution of PNIPAAm-NH2 increased slightly with increasing the AESH concentration. Alginate-g-PNIPAAm copolymer was synthesized by grafting PNIPAAn-NH2 onto sodium alginate using N-(3-dimethylami-nopropyl)-N`-ethylcarbodiimide and N-hydroxysuccinimide. The formation of the grafted copolymers was confirmed by FTIR spectroscopy, solubility in water, and SEM-EDS. Alginate-g-PNIPAAm also exhibited swelling-deswelling behave-ior. However, it showed a LCST at a slightly increased temperature compared to PNIPAAm. The swelling ratio of the alginate-g-PNIPAAm hydrogel increased with the increase of the grafted PNIPAAm content.

Synthesis of Thermo-responsive gel For Smart Windows Poly(N-isopropylacrylamide)-based materials

장지원,김일진,심재학,박현호,천지원,이동진 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Thermo-responsive polymer that exhibit phase transition in response to temperature change can be used as materials for smart windows because they can control solar light transmission depending on the outside temperature. Thermotropic polymers have a reversible sol-gel phase transition or volume phase transition at a certain temperature. The specific temperature at which the phase transition occurs is called LCST(Lower critical solution temperature) To obtain high performance smart windows materials, three-dimensional thermo-responsive poly (N-isopropylacrylamide) (PNIPAm) gels were prepared by free radical polymerization from monomer N-isopropylacrylamide, N,N’- methylenebis acrylamide (MBAm) as a crosslinking agent, ammonium persulfate (APS) as a oxidizing agent/N,N,N’,N’-tetramethylethylenediamine as a catalyst, and a mixure of solvents. This study examine the thermotropic polymer synthesis and LCST behavior with enhanced durability by capsulation.

가교도가 다른 열민감성 Poly(N-isopropylacrylamide) 수화겔의 팽윤 및 수축 거동

고재훈,김영호,Ko, Jae-Hoon,Kim, Young-Ho 한국섬유공학회 2007 한국섬유공학회지 Vol.44 No.3

Poly(N-isopropylacrylamide)(PNIPAAm) hydrogels were synthesized via radical polymerization of N-iso-propylacrylamide in aqueous medium using ammonium persulfate and N,N'-methylenebisacrylamide (MBA) as an initiator and a crosslinking agent, respectively. PNIPAAm hydrogels exhibited a critical gel transition temperature (CGTT) at $32{\sim}34^{\circ}C$. Swelling and deswelling behaviors of the hydrogels with different crosslinking densities were analyzed by measuring swelling ratio below and above CGTT. The swelling ratio of the hydrogel below CGTT decreased with increasing MBA concentration, while that above CGTT increased. As MBA concentration increased, the micropore size decreased, however, the number of micropore increased slightly in the freeze-dried hydrogels swollen in water at $25^{\circ}C$ (below CGTT) before drying. The micropore became smaller and denser in the des deswollen state. The swelling ratio of the hydrogels decreased slightly with the repeated swelling and deswelling treatment.

Fast thermo-responsive films composited of poly(N-isopropylacrylamide) and polydimethylsiloxane

김소연,이종휘,김준석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Poly(N-isopropylacrylamide) (PNIPAm) has received attention because of soluble-insoluble change at its lower critical solution temperature. The transition of PNIPAm need to be accelerated because the slow transition rate has made its applications difficult. In previous study, we developed thermo-responsive film, composed of PNIPAm hydrogels with aligned pores and infiltrated polydimethylsiloxane (PDMS), deswell to 10 % of its initial volume in 12 sec. To further improve deswelling rate, PNIPAm hydrogels having various pore sizes were prepared by directional melt crystallization and subsequently infiltrated PDMS into the pores of PNIPAm. We controlled the pore sizes of PNIPAm by controlling the concentration of NIPAm solutions, and the content of PDMS phase was controlled by the pore size of PNIPAm. The deswelling rate increased as the pore size of PNIPAm decreased. As a result, we demonstrated the transition rate of PNIPAm/PDMS composite could be controlled by PDMS phase in composites.

Synthesis and Thermo-responsive Properties of Chitosan-g-Poly (N-isopropylacrylamide) and HTCC-g-Poly(N-isopropylacrylamide) Copolymers

Lee, Eun-Ju,Kim, Young-Ho 한국섬유공학회 2010 FIBERS AND POLYMERS Vol.11 No.2

Carboxyl group-terminated poly(N-isopropylacrylamide) (PNIA-COOH) was synthesized via radical polymerization of N-isopropylacrylamide (NIA) using mercaptoacetic acid (MAA) as a chain transfer agent. The molecular weight of the PNIA-COOH was controlled by changing the molar ratio of MAA to NIA. A water-soluble chitosan derivative, N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), was also synthesized by reacting chitosan with glycidyltrimethylammonium chloride. Then, chitosan-g-PNIA and HTCC-g-PNIA copolymers were synthesized using the "graft-onto" method by reacting PNIA-COOH with chitosan and HTCC, respectively. The formation of the grafted copolymers was confirmed by Fourier transform infrared spectroscopy, solubility test in water, and scanning electron microscopy -energy dispersive spectroscopy. The thermo-responsive behaviors of the grafted copolymers and the change in lower critical solution temperature (LCST) were also studied. Chitosan-g-PNIA was insoluble in water and behaved like a thermo-responsive hydrogel due to the crosslinking-point action of the chitosan backbone. The swelling ratio of chitosan-g-PNIA increased with increasing PNIA content. HTCC-g-PNIA behaved as a water-soluble thermo-responsive polymer. Compared to the homo PNIA, the LCST of HTCC-g-PNIA was slightly increased.

Microstructure and Electrical Properties of Poly-N-isopropylacrylamide- N-vinylcarbazole Copolymers

Pierson, R.,Basavaraja, C.,Kim, Na-Ri,Jo, Eun-Ae,Huh, Do-Sung Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.9

Conducting poly-N-isopropylacrylamide-N-vinyl carbazole (PNI-nvc) copolymers were synthesized via in situ deposition technique by dissolving different weight percentages of N-vinyl carbazole (10, 20, 30, and 40%). The structural morphology and FT-IR studies support the interaction between PNI and N-vinyl carbazole. The temperaturedependent DC conductivity of PNI-nvc was studied within the range of 300 ${\leq}\;T\;{\leq}$ 500 K, presenting evidence for the transport properties of PNI-nvc. The DC conductivity of PNI-nvc copolymers signifies the future development of new nanocopolymers that acts as a multifunctional material.

β-Cyclodextrin conjugated thermosensitive block copolymers of poly(ethylene oxide)-block-poly(N-isopropylacrylamide-co-glycidyl methacrylate) for drug delivery

김용한,임권택,( Xuan Thang Cao ),김동우 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

A novel drug carrier system based on β-cyclodextrin functionalized block copolymers were synthesis. Thermosensitive block copolymers of poly(ethylene oxide)-block-poly(N-isopropylacrylamide-co-glycidyl methacrylate) (PEO-b-P(NIPAm-co-GMA)) were synthesized by reversible addition fragmentation chain transfer polymerization using a PEO macro-initiator. β-Cyclodextrin was simply attached to thermosensitive block copolymers by epoxide ring-opening reaction, which were then modified inclusion-complex formation of cyclodextrin with prednisolone acetate drug. The drug loading efficiency increased in the β-cyclodextrin conjugated polymer compared to native β-cyclodextrin. The thermo-responsive micelles enhanced cytotoxicity against human breast cancer cells in vitro.

Cooling Effect of Polyurethane / Poly(N-isopropylacrylamide) Composites

김수연,이종휘 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1

Environmental issues are becoming increasingly important. Now, sustainable and energy-free materials are in the spotlight of research and development. Cooling is not only required for buildings, but also for automotive engines, thermoelectric elements, etc. The previous studies on the composites of poly(N-isopropylacrylamide) (PNIPAm) have shown the advantages of cooling materials based on its unique lower critical solution temperature (LCST) behavior of rapid deswelling. In this study, we improved the thermal conduction for cooling applications, which was prepared by melt crystallization of water. As a component, polyurethane (PU) was used to control evaporation. Thermal conduction was improved by incorporation of aluminum nitride (AIN). This creates composites that allow control evaporation like skin epidermis. Also the infiltration of NIPAm solution into the PU pores prepared a novel hydrogel composite. Composites using this method will help future evaporative cooling systems.

Microstructure and Electrical Properties of Poly-N-isopropylacrylamide- N-vinylcarbazole Copolymers

R. Pierson,바사바,Na Ri Kim,Eun Ae Jo,허도성 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.9

Conducting poly-N-isopropylacrylamide-N-vinyl carbazole (PNI-nvc) copolymers were synthesized via in situ deposition technique by dissolving different weight percentages of N-vinyl carbazole (10, 20, 30, and 40%). The structural morphology and FT-IR studies support the interaction between PNI and N-vinyl carbazole. The temperaturedependent DC conductivity of PNI-nvc was studied within the range of 300 ≤ T ≤ 500 K, presenting evidence for the transport properties of PNI-nvc. The DC conductivity of PNI-nvc copolymers signifies the future development of new nanocopolymers that acts as a multifunctional material.

미세채널을 이용한 폴리(N-이소프로필아크릴아미드) 마이크로 하이드로젤의 합성 및 농도측정 센서 용도

강신혜(Shin Hye Kang),김서균(Seo Gyun Kim),이헌상(Heon Sang Lee) 한국고분자학회 2018 폴리머 Vol.42 No.6

본 연구에서는 소프트리소그래피(soft lithography) 공정을 이용하여 폴리디메틸실록산(polydimethylsiloxane, PDMS) 재질의 미세채널을 제작하였고, 이를 활용하여 구형의 폴리(N-이소프로필아크릴아미드)(poly(N-isopropylacrylamide), PNIPAm) 미세-하이드로젤을 합성하였다. 합성된 미세-하이드로젤은 온도가 상승할수록 부피가 감소하였으며, 32 ℃ 주변에서 최저임계용액온도(lower critical solution temperature, LCST) 거동을 보였다. 미세-하이드로젤을 폴리비닐알코올(poly(vinyl alcohol), PVA) 용액 또는 염화나트륨(sodium chloride, NaCl) 용액에 담구었을 때, 용액의 농도 및 온도에 따른 미세-하이드로젤의 부피변화를 관찰하였다. 부피변화로부터 미세-하이드로젤에 포함된 물과 고분자의 부피분율 변화를 계산하였다. Flory-Huggins 이론을 도입하여 각 용액의 농도 및 온도에 따른 삼투압 변화를 확인하였다. 측정된 부피변화와 삼투압 변화 결과로부터 제조된 미세-하이드로젤은 온도 및 농도측정 센서로 활용가능함을 확인하였다. In this study, PDMS microchannels were fabricated by using a soft lithography process. Poly(N-isopropylacrylamide) (PNIPAm) micro-hydrogel spheres were synthesized by using the microfluidic channel. The volume of synthesized micro-hydrogel was reduced as increasing temperature, exhibiting lower critical solution temperature (LCST) behavior at around 32 ℃. The volume changes of the micro-hydrogels were monitored as they were immersed into poly(vinyl alcohol) (PVA) or sodium chloride (NaCl) solution. The effects of temperature and solution concentration on the volume of the micro-hydrogels were investigated. The osmotic pressures of the micro-hydrogels were calculated from the solid contents in the micro-hydrogel by using the Flory-Huggins theory. It was suggested that the micro-hydrogel can be used as a sensor detecting concentration of solution and temperature.