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방승훈,김정안,권난현,김형철,Abu Bakkar Siddique,강호중,이재열,김주훈,김세훈 한국고분자학회 2014 Macromolecular Research Vol.22 No.4
Versatile and direct synthesis of water-dispersible titanium dioxide (TiO2) nanoparticles in the presenceof functionalized poly(ethylene oxide)s (PEO) having carboxylic acid groups is presented. The functionalized PEOs,such as PEO-folate conjugate and PEO-b-poly(maleic acid) (PEO-b-PMAc) as polymeric surfactants, were employedfor in situ synthesis of TiO2 nanoparticles through hydrolytic sol-gel process of titanium tetrachloride as a precursorin eco-friendly alcoholic media at a relatively low temperature. Both of the two polymers were found to be very effectivefor stabilizing TiO2 nanocrystals, exhibiting not only fairly good photocatalytic activities but also water-dispersibleproperty. The core TiO2 crystallites in the size range of 8~11 nm could be readily controlled in ethanol at a relativelylow reaction temperature (70 oC), irrespective of the incipient reaction condition, which showed mixed polymorphs. The TiO2 nanoparticles consist of a few percentages (<10%) of brookite and mostly anatase phases. This processprovides a simple and useful in situ preparative route to obtain water-dispersible TiO2 nanoparticles.
남주현,김정안,최우석,이재혁,권난현,강호정,이재열,김세훈 한국고분자학회 2012 Macromolecular Research Vol.20 No.11
In this paper, the important and useful method for manufacturing superparamagnetic iron oxide nanoparticles stabilized by water-soluble poly(ethylene oxide) (PEO)-based triblock copolymers showing stimuli-responsive phase transition is introduced. Triblock copolymers, such as poly(ethylene oxide-b-N-vinylimidazole-b-3-(methacrylamino)phenylboronic acid) (PEO-b-PVIm-b-PMAPBA), poly(ethylene oxide-b-N-vinylpyrrolidone-b-3-(methacrylamino)phenylboronic acid) (PEO-b-PVP-b-PMAPBA), and poly(ethylene oxide-b-N-vinylimidazoleb-maleic acid) (PEO-b-PVIm-b-PMAc), were synthesized using the sequential monomer addition method via reversible addition fragmentation chain transfer (RAFT) radical block copolymerizations of the corresponding monomers, using PEO-based RAFT agent. After complete polymerization of N-vinylimidazole or N-vinylpyrrolidone in dimethylformamide (DMF) at 110 oC, 3-(methacrylamino)phenylboronic acid (MAPBA) was polymerized in DMF at 90 oC for 24 h, and N-phenylmaleimide was polymerized in dimethylsulfoxide (DMSO) at 110 oC for 28 h. All the block copolymers were water-soluble and efficient enough to stabilize the surface of nano-sized iron oxide particles in water. The nanoparticles were stable in neutral aqueous media for at least one month. The resulting products were characterized by a combination of 1H nuclear magnetic resonance spectroscopy (NMR), size exclusion chromatography, transmission electron microscopy (TEM), electron diffraction pattern, and phase transition behavior of the block copolymers using UV/visible spectrophotometer.