• 폴리머
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• 제25권2호
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• pp.263-269
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• 2001

나트륨 몬모릴로나이트($Na^{+}$-MMT)의 양이온을 3-(methacryloyl amino) propyl trimethyl ammonium chloride (MAPTAC)와 교환반응시켜 몬모릴로나이트의 표면을 친유성으로 개질시키는 동시에, 단량체와 공중합을 할 수 있는 이중결합이 부착된 MAPTAC-MMT를 제조하였다. 상온에서 MAPTAC-MMT가 분산된 수용액에서 N-isopropyl acryl amide (NIPAM)를 중합하여 열응답성 나노복합재료(PNIPAM-MMT)를 제조하였다. MAPTAC-MMT으로부터 제조된 열응답성 나노복합재료는 열응답성 고분자인 poly(N-isopropyl acrylamide) (PNIPAM)와 마찬가지 하한임계용액온도(LCST)를 나타내었으며, MAPTAC-MMT의 양이 증가함에 따라 PNIPAM-MMT의 LCST는 감소하였다. 또한 TGA실험 결과에서 열응답성 나노복합재료의 열안정성이 열응답성 고분자에 비하여 우수하였음을 보였다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.374-374
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• 2006

Poly (N-isopropylacrylamide) (PNIPAAm) shows a lower critical solution temperature (LCST) at $32^{\circ}C$. Consequently, its thermosensitivity has extensively been investigated in coating materials as well as biomedical and agricultural industry. However, mechanical properties of the swollen gels are generally poor and reinforcement is often desired. A series of interpenetrating polymer networks (IPNs) and emulsion blends hydrogels of polyurethane (PU) and PNIPAAm were prepared in order to overcome the shortcomings of a normal PNIPAAm hydrogels. Regarding the mechanical reinforcement of swollen gel, a significant increase in compression and tensile properties has been obtained by incorporating PU.

• Korean Membrane Journal
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• 제6권1호
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• pp.37-43
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• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1629-1630
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• 2004

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.189-195
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• 2017

Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the $R_2$ maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

• 폴리머
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• 제25권2호
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• pp.186-198
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• 2001

pH와 온도에 민감한 N-isopropylacrylamide (NIPAAm)계 공중합체인 poly(NIPAAm-co-AAc), Poly(NIPAAm-co-AAm-GAc), 및 poly(NIPAAm-co-AMPS)를 산성 공단량체의 조성비를 달리하여 자유라디칼 중합법에 의해 제조하였다. 합성된 공중합체들의 하한임계용액온도 거동(LCST)에 대한 pH와 공단량체의 구조 및 함량변화 효과를 열광학분석기 (TOA)를 이용하여 측정한 흐림점으로부터 결정하였다. Poly(NIPA.Am-co-AAc) 수용액의 상전이온도(T$^{p}$ )는 공중합체내 AAc의 카르복실기가 이온화될수록, 보다 높은 값을 나타내었는데, 이와 같은 현상은 이온화된 상태에서 공중합체내 이온기들간의 정전기적 반발력이 보다 친수성을 나타나게 한 원인이 되었다. 반면에, 2-acrylamido glycolic acid (AAmGAc)가 공중합체에 도입된 경우, pH 3보다 낮은 pH에서는 T$^{p}$ 의 변화가 거의 없었지만, pH 3에서 5까지는 T$^{p}$ 가 매우 급격히 증가하였다가 pH 6이상에서는 공중합체의 T$^{p}$ 가 ionic screen effect에 의해 pH 3에서 pH 5일 때보다 오히려 더 낮아졌다. 또한 이 같은 ionic screen effect는 강산성 공단량체로 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)가 도입된 공중합체 의 경우에서도 관찰되었다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2007년도 학술발표회 논문집
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• pp.349-350
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• 2007

• 폴리머
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• 제24권2호
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• pp.168-173
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• 2000

자유 라디칼 개시제인 2,2'-azobisisobutyronitrile (AIBN)을 사용하여 1,4-dioxane 용매하에서 N-isopropylacrylamide (NIPAAM)와 methyl methacrylate (MMA)를 공중합하였다. 온도에 따른 NIPAAM과 MMA의 반응성비를 알아보기 위해 각각 50, 60, 7$0^{\circ}C$에서 중합하여 전환율이 10 wt%이하가 되도록 반응을 정지시켰다. 단량체 반응성비는 Finemann-Ross법으로 구하였으며, 그 값은 5$0^{\circ}C$에서는 ${\gamma}$$_2$=0.259, ${\gamma}$$_2$=2.782, 6$0^{\circ}C$에서는 ${\gamma}$$_1$=0.271, ${\gamma}$$^2$=0.819, 그리고 7$0^{\circ}C$에서는 ${\gamma}$$_1$=0.286, ${\gamma}$$_2$=2.915로 나타나, 반응온도가 높아질수록 ${\gamma}$$_1$, ${\gamma}$$_2$ 값이 증가함을 알 수 있었다. 또한 반응온도와 반응성비와의 관계로부터 활성화에너지의 차를 구할 수 있었으며, 그 결과 반응성비는 온도 의존성이 있는 것으로 나타났다.

• Biomaterials and Biomechanics in Bioengineering
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• 제1권2호
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• pp.105-116
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• 2014

Synthesis of interpenetrating polymer network (IPN) of chitosan-gelatin (Cs-Ge) (as a primary network) and N-isopropylacrylamide (NIPAAm) monomer (as the secondary network) was carried out with different ratio. Its structure was characterized by FT-IR, which indicated that the IPN was formed. The memberanes were studied by swelling, weight loss with time. The interior morphology of the IPN hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a interpenetrated network of NIPAAm/chitosan has layers with more minute stoma and canals compared to interpenetrated network of NIPAAm/gelatin. Lower critical solution temperature (LCST), equilibrium swelling ratio (ESR) and deswelling kinetics were measured. The DSC results noticed that LCST of IPN hydrogels with different ratio of Cs/Ge/PNIPAAm are around $33{\pm}2^{\circ}C$. The ESR obtained results showed that with a ratio of Cs/Ge/NIPAAm: 1/1/6, the swelling ratio increased drastically from room temperature to $36^{\circ}C$ but with a ratio of Cs/Ge/PNIPAAm: 1/3/6, decrease significantly at the same condition. Therefore the hydrogels have been changed from a hydrophilic structure to a hydrophobic structure. Furthermore with an increase in temperature from room to the LCST, the ESR of IPN with higher concentration of (PNIPAAm) and (Ge) decreases but de-swelling kinetics of them are faster. Due to the suitable and different kinetics of de-swelling and the equilibrium swelling ratio (ESR) in various proportions, and because of the morphology inside the mass which confirms other tests, these hydrogels are very appropriate as a smart thermosensitive hydrogels with rapid response.

• Macromolecular Research
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• 제14권1호
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• pp.87-93
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• 2006

Copolymers composed of hyaluronic acid (HA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to create temperature-sensitive injectable gels for use in controlled drug delivery applications. Semi-telechelic PNIPAAm, with amino groups at the end of each main chain, was synthesized by radical polymerization using 2-aminoethanethiol hydrochloride (AESH) as the chain transfer agent, and was then grafted onto the carboxyl groups of HA using carbodiimide chemistry. The result of the thermo-optical analysis revealed that the phase transition of the PNIPAAm-grafted HA solution occurred at around 30$\∼$33$^{circ}C$. As the graft yield of PNIPAAm onto the HA backbone increased, the HA-g-PNIPAAm copolymer solution exhibited sharper phase transition. The short chain PNIPAAm-grafted HA ($M_{w}$=6,100) showed a narrower temperature range for optical turbidity changes than the long chain PNIPAAm-grafted HA ($M_{w}$=13,100). PNIPAAm-grafted HA exhibited an increase in viscosity above 35$^{circ}C$, thus allowing the gels to maintain their shape for 24 h after in vivo administration. From the in vitro riboflavin release study, the HA-g-PNIPAAm gel showed a more sustained release behavior when the grafting yield of PNIPAAm onto the HA backbone was increased. In addition, BSA released from the PNIPAAm-g-HA gels showed a maximum concentration in the blood 12 h after being injected into the dorsal surface of a rabbit, followed by a sustained release profile after 60 h.