• Membrane Journal
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• v.20 no.1
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• pp.1-7
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• 2010

A graft copolymer, i.e. poly(vinylidene fluoride-co-chlorotrifluoroethylene )-g-poly(styrene sulfonic acid) (P(VDF-co-CTFE)-g-PSSA) with 47 wt% of PSSA was synthesized via atom transfer radical polymerization (ATRP). This copolymer was combined with titanium isopropoxide (TTIP) to produce graft copolymer/$TiO_2$ nanocomposite membranes via sol-gel process. $TiO_2$ precursor (TTIP) was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grown to form $TiO_2$ nanoparticles, as confirmed by FT-IR and UV-visible spectroscopy. Water uptake and ion exchange capacity (IEC) decreased with TTIP contents due to the decrease in number of sulfonic acid in the membranes. At 5 wt% of TTIP, the mechanical properties of membranes increased while maintaining the proton conductivity.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.453-456
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• 1998

고분자들을 배합하여 기계적, 물리적, 화학적 성질이 우수한 새로운 고분자 재료를 제조할 때 이들 고분자의 상용성을 증가시켜 줄 수 있는 상용화제의 존재가 필수적인데, 주로 블록이나 그라프트 공중합체들이 많이 이용되고 있다. 이러한 공중합체들은 아주 최소량이 사용되고서도 소기의 목적을 달성할 수 있어야 하는데, 이를 위해서는 이러한 공중합체들은 분자구조상 몇 가지 조건을 만족해야 한다. 예를 들면 계면에 존재하면서 넓은 표면적을 감싸주어야 하고 블렌드되는 고분자들과 아주 잘 섞여야 한다는 것 등이 그것이다. (중략)

• Membrane Journal
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• v.31 no.4
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• pp.268-274
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• 2021

One of the chronic problems in the issue of global warming is the emission of greenhouse gases. Carbon dioxide (CO₂), which accounts for the highest proportion of various greenhouse gases, has been continuously researched by humans to separate it. From this point of view, a poly(vinyl alcohol) (PVA)-based copolymer with acrylic acid monomer was utilized in a gas separation membrane in this study. We employed a free radical polymerization to fabricate PVA-g-PAA (VAA) graft copolymer. It was utilized in the form of a composite membrane on a polysulfone substrate. The proper amount of acrylic acid reduced the crystallinity of PVA and increased CO₂ solubility in separation membranes. In this perspective, we suggest the novel approach in CO₂ separation membrane area by grafting and solution-diffusion.

• Membrane Journal
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• v.20 no.3
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• pp.203-209
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• 2010

Amphiphilic graft copolymers based on poly(epichlorohydrine) (PECH) were synthesized using atom transfer radical polymerization (ATRP). Successful graft polymerization of poly(methyl methacrylate)(PMMA) and poly(butyl methacrylate) (PBMA) from PECH was confirmed by nuclear magnetic resonance ($^1H$ NMR) and FT-IR spectroscopy. Upon the introduction of KI or LiI to the graft copolymers, the ether stretching bands were shifted to a lower wavenumber due to coordinative interactions. Ionic conductivities of PECH-g-PBMA complexes were always higher than those of PECH-g-PMMA complexes, resulting from higher mobility of rubbery PBMA chains. The maximum ionic conductivity of $2.7{\times}10^{-5}\;S/cm$ was obtained at 10 wt% of KI for PECH-g-PBMA electrolytes.

• Polymer(Korea)
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• v.31 no.4
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• pp.302-307
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• 2007

The resistive-type humidity sensors were prepared from the copolymers of [2-[(methacryloyloxy)ethyl]dimethyl]propylamonium bromide (MEPAB), [2-[(methacryloyloxy)ethyl]-2-hydroxyethyl]dimethylammonium bromide (MEHDAB), 2- [(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), and n-butyl methylacrylate (MBA). Four component copolymers MEPAB/BMA/MEHDAB/METAC=4/4/1/1, 3/5/1/1, 2/6/1/1, 1/7/1/1 crosslinked with blocked-isocyanate on Ag/Pd electrode/alumina substrate showed a good durability at high humidities. The various electrical properties such as frequency dependency, temperature dependency, hysteresis, response time and water durability were examined. In the case of copolymer composed of MEPAB/BMA/MEHDAB/METAC=2/6/1/1, the resistance varied from $1.4\;M{\Omega}$ to $2.9\;k{\Omega}$ at $25^{\circ}C$ in the range of $30{\sim}90\;%RH$ and this copolymers showed a good linearity and low hysteresis.

• Polymer(Korea)
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• v.31 no.3
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• pp.194-200
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• 2007

The resistive-type polymeric humidity sensors were prepared from the copolymers of [2- [(methacryloyloxy)ethyl] dimethyl] propylammonium bromide(MEPAB), [2- [(methacryloyloxy)ethyl]-2-hydroxyethyl]dimethylmonium bromide (MEHDAB), n-butyl methylacrylate(MBA), 2-hydroxyethyl methylacrylate(HEMA) and styrene. Four kinds of copolymers, ie, MEPAB/styrene/MEHDAB MEHDAB/BMA/HEMA, MEPAB/BMA/MEHDAB, and MEPAB/styrene/HEMA crosslinked with blocked-isocyanate on the Ag/Pd electrode/alumina substrate showed good durability at high humidities. The various electrical properties such as frequency dependency, temperature dependency, hysteresis, response time and water durability were examined. In the case of copolymer MEPAB/BMA/MEHDAB= 3/6/1, the resistance was varied from $2.9 M{\Omega}$ to $1.84k{\Omega}$ at $25^{\circ}C$ in the range of $30{\sim}90%RH$ and this copolymers showed a good linearity and low hysteresis.

• Polymer(Korea)
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• v.28 no.5
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• pp.367-373
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• 2004

Novel non-conjugated blue light-emitting copolymers containing perylene and triazine moieties as light emitting and electron transporting units, respectively in the polymer side chain were synthesized. The resulting copolymers were soluble in most organic solvents such as chlorobenzene, THF, chloroform and benzene. The single-layered electroluminescence (EL) device consisting of indium tin oxide (ITO) /copolymer/aluminium (Al) exhibited a maximum external quantum efficiency ($0.003\%$) and a good carrier balance when the triazine content was $30\%$. In particular, the device emitted blue light (479 nm) corresponding to the emission of perylene moiety. The drive voltage was observed at 5 V and the CIE coordinate was x=0.16, y=0.17.

• Polymer(Korea)
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• v.34 no.6
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• pp.501-506
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• 2010

Natural chitosan has high molecular weight and the poor solubility in water. Water-soluble chitosan with low molecular weight was prepared by the hydrolysis method. In order to develop an efficient gene delivery carrier, chitosan was conjugated with lipoic acid to form the comb-type copolymer. The copolymer with the amphiphilic property formed the self-assembled nanoparticles in the aqueous solution. The average size of nanoparticles was 217.6 nm and the average size of nanoparticles/DNA complex was 170 nm. New chitosan-lipoic acid copolymer showed the low cytotoxicity and 10 times higher transfection efficiency than that of the pure chitosan.

• Membrane Journal
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• v.19 no.2
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• pp.96-103
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• 2009

A series of organic-inorganic composite membranes from poly(vinyl chloride) (PVC) graft copolymer electrolyte and heteropolyacid (HPA) were prepared for proton conducting membranes. First, poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA) was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC. HPA nanoparticles were then incorporated into the PVC-g-PSSA graft copolymer though the hydrogen bonding interactions, as confirmed by FT-IR spectroscopy. The proton conductivity of the composite membranes increased from 0.049 to 0.068 S/cm at room temperature with HPA contents up to 0.3 weight traction of HPA, presumably due to both the intrinsic conductivity of HPA particles and the enhanced acidity of the sulfonic acid of the graft copolymer. The water uptake decreased from 130 to 84% with the increase of HPA contents up to 0.45 of HPA weight traction, resulting from the decrease in number of water absorption sites due to hydrogen bonding interaction between the HPA particles and the polymer matrix. Thermal gravimetric analysis (TGA) demonstrated the enhancement of thermal stabilities of the composite membranes with increasing concentration of HPA.

• Membrane Journal
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• v.29 no.6
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• pp.323-328
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• 2019

It is a highly important problem for mankind to supply sufficient energy, which has been connected to production and supply of electricity. In terms of the problems, this study fabricated a new sort of solid polymer electrolyte membrane for supercapacitors. The fabricated electrolyte employed grafting poly(oxyethylene methacrylate) (POEM) side chain on poly(vinyl alcohol) (PVA) main chain by free-radical polymerization. It is the first time to utilize PVA-g-POEM graft copolymer as an electrolyte membrane for supercapacitor. The chain behavior of PVA was transformed by grafting POEM side chains, which was analyzed by FT-IR spectra. Also, the capacitance performances of fabricated supercapacitors were explored by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and ragone plot. We suggest a new point, the grafting of the electrolyte of supercapacitor in this study.