• Title/Summary/Keyword: Poly(N-isopropylacrylamide)

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Synthesis and Characterization of Thermo Sensitive Poly(styrene-co-N-isopropylacrylamide) Microgels (열 감응성 Poly(styrene-co-N-isopropylacrylamide) 마이크로겔의 합성 및 특성)

  • Cho, Suk Hyeong;Kim, Kong Soo;Jung, Tea Uk
    • Applied Chemistry for Engineering
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    • v.16 no.3
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    • pp.397-402
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    • 2005
  • Core-shell Poly(styrene-co-N-isopropylacrylamide) (poly(St-co-NIPAm) was prepared by soap-free emulsion polymerization of styrene (St) and N-isopropylacrylamide (NIPAm) in aqueous solution with potassium persulfate (KPS) as an initiator. The effects of St/NIPAm ratio, concentrations of monomer and crosslinker were studied. Also, Thermo sensitivity of microgels prepared was investigated. Particle size of microgels increased with increasing mol ratio of NIPAm to styrene. Transmittance of the microgel dispersion decreased rapidly when heated above a low critical solution temperature (near $32{\sim}34^{\circ}C$, cloud point). Swelling ratio of the microgel increased with increasing of the concentration of monomer (NIPAm) and decreased proportional to the concentration of crosslinker.

Temperature-Dependent Release of Drug from Copolymers of N-Isopropylacrylamide Containing Liposome (리포솜이 함유된 N-이소프로필아크릴아마이드의 공중합체로부터 온도에 따른 약물의 방출)

  • 박영심;한희동;홍성욱;김승수;신병철
    • Polymer(Korea)
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    • v.28 no.1
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    • pp.59-66
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    • 2004
  • Thermosensitive poly(N-isopropylacrylamide) gels containing temperature-sensitive liposomes showing temperature-dependent sol-gel transition were prepared. The surface of temperature-sensitive liposome was modified with copolymers of N-isopropylacrylamide and octadecylacrylate, which exhibited a lower critical solution temperature at around 30 $^{\circ}C$ After mixing the modified temperature-sensitive liposomes with poly(N-isopropylacrylamide) solution, the temperature-sensitive 1iposomes formed physically cross-linked gels through heating the solution above their lower critical solution temperatures. The release of drug from temperature-sensitive liposomes was determined by measuring fluorescence intensity. The drug release from temperature-sensitive liposomes in poly(N-isopropylacrylamide) gel gradually showed sustained-release with increasing temperature.

Syntheses and Swelling Behaviors of Poly(n-isopropylacrylamide-co-acrylonitrile) Hydrogels (Poly(N-isopropylacrylamide-co-acrylonitrile) 수화젤의 합성과 팽윤거동)

  • Piao, Zhe Fan;Ham, Myong-Jo;Kim, Young-Ho
    • Polymer(Korea)
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    • v.31 no.4
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    • pp.349-355
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    • 2007
  • Poly(N-isopropylacrylamide-co-acrylonitrile) [P(NIPAAm-co-AN)] copolymers with AN content of up to 10 mol% and their hydrogels were synthesized using water as a reaction medium, and the effects of AN unit incorporation on the critical gel transition temperature(CGTT) and swelling behaviors of the hydrogels were investigated. The CGTT of the copolymer hydrogel was $30{\sim}32\;^{\circ}C$, decreasing with increasing AN content. Below CGTT, swelling rate and equilibrium swelling ratio of the copolymer hydrogel decreased with increasing AN content. On the other hand, it exhibited faster deswelling and lower equilibrium deswelling ratio with increasing AN content above CGTT.

Velume Phase Transition of Poly (N-isopropylacrylamide-co-sodium methacrylate) Hydrogel Crosslinked with Poly(ethylene glycol) diacrylate (Poly(ethylene glyco1) diacrylate로 가교된 Poly(N-isopropylacrylamide) Hydrogel의 부피 상전이 특성)

  • 김선아;한영아;손성옥;지병철
    • Polymer(Korea)
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    • v.26 no.5
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    • pp.653-660
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    • 2002
  • The volume phase transition of poly(N-isopropylacrylamide) (PNIPAAm) and poly (N-isopropylacrylamide-co-sodium methacrylate) (P (NIPAAm-co-SMA)) hydrogels crosslinked with poly (ethylene glycol) diacrylate (PEGDA) was investigated in consideration of water content and surface area. The volume phase transition temperature of hydrogel was not affected by the concentration of crosslinking agent, which increased over 40$\^{C}$ by incorporating a small amount of SMA. Higher volume phase transition temperature was obtained when PEGAD was used as a crosslinking agent, suggesting that the chain length of crosslinking agent had a significant effect on the volume phase transition temperature. The surface area of PNIPAAm and P (NIPAAm-co-SMA) gels fell off around the volume phase transition temperature, resulting from the fact that the size of pores reduced remarkably in the course of the volume phase transition. Hence, the surface area and the pore size were considered to be important factors indicating the volume phase transition.

Relative Parameter Contributions for Encapsulating Silica-Gold Nanoshells by Poly(N-isopropylacrylamide-co-acrylic acid) Hydrogels

  • Park, Min-Yim;Lim, Se-Ra;Lee, Sang-Wha;Park, Sang-Eun
    • Macromolecular Research
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    • v.17 no.5
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    • pp.307-312
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    • 2009
  • Core-shell hydrogel nanocomposite was fabricated by encapsulating a silica-gold nanoshell (SGNS) with poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) copolymer. The oleylamine-functionalized SONS was used as a nanotemplate for the shell-layer growth of hydrogel copolymer. APS (ammonium persulfate) was used as a polymerization initiator to produce a hydrogel-encapsulated SGNS (H-SGNS). The amounts of NIPAM (N-isopropylacrylamide) monomers were optimized to reproduce the hydrogel-encapsulated SGNS. The shell-layer thickness was increased with the increase of polymerization time and no further increase in the shell-layer thickness was clearly observed over 16 h. H-SGNS exhibited the systematic changes of particle size corresponding to the variation of pH and temperature, which was originated from hydrogen-bonding interaction between PNIPAM amide groups and water, as well as electrostatic forces attributed by the ionization of carboxylic groups in acrylic acid.

Synthesis and Thermo-responsive Properties of Amino Group Terminated Poly(N-isopropylacrylamide) and Sodium Alginate-g-Poly(N-isopropylacrylamide) (말단 아민기를 갖는 폴리(N-이소프로필아크릴아미드) 및 알긴산 나트륨-g-폴리(N-이소프로필아크릴아미드)의 합성과 열응답 특성)

  • Lee, Eun Ju;Kim, Young Ho
    • Polymer(Korea)
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    • v.37 no.4
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    • pp.539-546
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    • 2013
  • Amino group-terminated poly(N-isopropylacrylamide) (PNIPAAm-$NH_2$) was synthesized via a radical polymerization of N-isopropylacrylamide (NIPAAm) using 2-aminoethanethiol hydrochloride (AESH) as a chain transfer agent. The molecular weight of the PNIPAAm-$NH_2$ was controlled by changing the concentration of AESH. The LCST of the aqueous solution of PNIPAAm-$NH_2$ increased slightly with increasing the AESH concentration. Alginate-g-PNIPAAm copolymer was synthesized by grafting PNIPAAm-$NH_2$ onto sodium alginate using N-(3-dimethylaminopropyl)-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 behavior. 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.

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

  • Pierson, R.;Basavaraja, C.;Kim, Na-Ri;Jo, Eun-Ae;Huh, Do-Sung
    • Bulletin of the Korean Chemical Society
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    • v.30 no.9
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    • pp.2057-2060
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    • 2009
  • 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.

Drug Release from Thermo-Responsive Self-assembled Polymeric Micelles Composed of Cholic Acid and Poly(N-isopropylacrylamide)

  • Kim, In-Sook;Jeong, Young-Il;Lee, Yun-Ho;Kim, Sung-Ho
    • Archives of Pharmacal Research
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    • v.23 no.4
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    • pp.367-373
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    • 2000
  • Cholic acid, conjugated with amine-terminated poly(W-isopropylacrylamide) (abbreviated as CA/ATPNIPAAm), was synthesized by a N, N'-dicyclohexyl carbodiimide (DCC)-mediated coupling reaction. Self-assembled CA/ATPNIPAAm micelles were prepared by a diafiltration method in aqueous media. The CA/ATPNIPAAm micelles exhibited a lower critical solution temperature (LCST) at $31.5^{\circ}C$. Micelle sizes measured by photon correlation spectroscopy (PCS) were approximately 31.6 $\times$$\times$ 5.8 nm. The CA/ATPNIPAAm micelles were spherical and their thermal size transition was observed by transmission electron microscope (TEM). A fluorescence probe technique was used for determining the micelle formation behavior of CA/ATPNIPAAm in aqueous solutions using Pyrene as a hydrophobic Probe. The critical micelle concentration (CMC) was evaluated as $8.9{\times}0^{-2}$ g/L. A drug release study was performed using indomethacin (IN) as a hydrophobic model drug. The release kinetics of IN from the CA/ATPNIPAAm micelles revealed a thermo-sensitivity by the unique character of poly(N-isopropylacrylamide) i.e. the release rate was higher at $25^{\circ}C$ than at $37^{\circ}C$.

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Synthesis and Characterization of Poly(N-isopropylacrylamide) Containing Polydimethylsiloxane (Polydimethylsiloxane을 함유한 poly(N-isopropylacrylamide)? 합성 및 성질)

  • Kim, Young-Sung;Bae, Min-Ae;Yoon, Koo-Sik
    • Journal of the Korean Chemical Society
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    • v.45 no.3
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    • pp.230-235
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    • 2001
  • Poly(N-isopropylacrylamide) (PNIPAAm) containing polydimethylsiloxane (PDMS) was synthesized using PDMS as crosslinking agent, and characterized by IR and DSC. It seems that the copolymer has separated phases, PNIPAAm and PDMS. The $T_g$ of PNIPAAm was decreased in accordance with the increase of PDMS-contents. The swelling behavior of polymer in water was examined with the function of temperature and PDMS-contents as well. The equilibrium swelling ratio of polymer in water was decreased with increasing PDMS-contents, but lower critical solution temperature (LCST) was not significantly affected by the incorporated PDMS-contents.

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