• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.104-110
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• 2008

Poly(allylamine) hydrochloride is a weak cationic polyelectrolyte that exhibits different aggregation properties at different solution pH values and aging times. Specifically, after several days aging in a pH 3 buffer, less than 1 mg/mL poly(allylamine) hydrochloride became turbid, and the hydrodynamic radius increased with a single diffusion mode. However, the hydrodynamic radius did not change at high concentrations. The dynamic processes of polymer aggregations at different pH values were verified by a light scattering and zeta-potential apparatus. The major interaction was caused by the capturing of counterions by the polyelectrolyte, which generates electrostatic, hydrophobic and cation-p interactions.

• Macromolecular Research
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• v.13 no.3
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• pp.265-272
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• 2005

Polyelectrolyte membranes for humidity-sensing were fabricated using a layer-by-layer adsorption process based on the spontaneous self-assembly of alternating layers of cationic and anionic polymers on a silanized ITO patterned glass substrate. The substrate is dipped successively into dilute solutions of a polyanion and a polycation. The homopolymers and copoymers of diallyldimethylammonium chloride (DDA), allylamine hydrochloride (AA), 2-[(methacryloyloxy)ethyl]trimethyl ammonium chloride (METAC) and vinylbenzyl tributyl phosphonium chloride(VTBPC) were used as the polycations. In this experiment, it was found that the resistance varied according to the chemical structure of the polycation. The resistance varied from $10^7$ to $10^5$ $\Omega$, as the humidity was increased from 60 (relative humidity) to $95\%$RH, which is the range of RH values required for a dew sensor operating at high humidity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.815-822
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• 2016

The cationic biopolymer chitosan has several applications in medicine. Chitosan is the deacetylated derivative of chitin, the second most abundant naturally occurring polymer. Recent studies have investigated the relationship between chitosan and antibacterial activity. However, the molecular interactions and mechanisms have not been detailed. This study used molecular dynamics simulations to study interactions between chitosan and anionic bacterial membranes (POPE-POPG) and electrically neutral non-bacterial membranes (POPC). We calculated the free energy using umbrella sampling to compare the interactions between membranes and chitosan in different protonation states. Fully protonated chitosan interacted most strongly with the bacterial membranes, but weakly with non-bacterial membranes. These results suggest that electrostatic interactions are the main mechanism of the antibacterial activity of chitosan, and they provide insights into the design of novel antibacterial and antimicrobial agents.

• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.63-67
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• 2007

Biodegradable cationic poly(ester-amide) polymers were synthesized by double-monomer method, that showed excellent solubility in many organic solvents and water. Different degradation patterns were obtained by the regulation of monomer ratios and overall long period of time of DNA protection up to 12 days was shown by PicoGreen reagent assay. Good transfection profiles in the presence of serum and very low toxicity on mammalian cells may allow these polymers to become suitable for long-term gene delivery systems and therapeutic applications.

• Textile Coloration and Finishing
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• v.24 no.4
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• pp.239-246
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• 2012

The binding isotherms of ionic dyes with Poly(vinylpyrrolidone) in aqueous solution were determined by the dynamic dialysis technique. The shape of the isotherms of cationic dye, C. I. Basic Red 18 with poly(vinlypyrrolidone) showed a partition type. It suggests that the binding involves a non-cooperative mode. Isotherms of an anion dye, a synthesized dye by coupling of diazotized m-trifluoromethylaniline with 2-naphthol-6-sulfonic acid, were sigmoid type and showed multimode interaction. The results were interpreted by the McGhee von Hippel theory. The thermodynamic parameters for the complex formation of the dyes-polymer were calculated from their temperature dependences of the intrinsic binding constant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.930-933
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• 2003

The electrochemical oxidation of ascorbic acid(AA), serotonin(StT) and epinephrine(EP) have been performed ae poly N,N-dimethylanliline(PDMA) film coated diamond electrode. This cationic polymer film is electrochemically deposited on boron-doped diamond electrode surface. Unlike the bard electrode, the polyaer film-coated diamond electrode can well separate the oxidation potential of AA by 330mV. Thus this electrode can be successfully used for the simultaneoud detection of both species. Increases in the concentration of AA donot affect the reponse of EP and ST.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1195-1199
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• 1999

2-(2,4,5-Trimethoxyphenyl)-4-methylene-1,3-dioxolane (1b), 2-(2,4,6-trimethoxyphenyl)-4-methylene-1,3-di-oxolane (2b), and 2-(3,4,5-trimethoxyphenyl)-4-methylene-1,3-dioxolane (3b) were prepared and polymerized with boron trifluoride. Boron trifluoride catalyzed reaction proceeded via mainly ring-opening polymerization and cyclization reaction to yield poly(keto ether) and 3(2H)-dihydrofuranone. The yields of polymer and cyclized product exhibited a dependency on the position of the methoxy substituents in the benzene ring of 2-phenyl-4-methylene-1,3-dioxolane derivatives. Electrophilic attack of methylene or oxygen atom on 4-meth-ylene-1,3-dioxolane ring were suggested for the polymerization and cyclization.

• Polymer(Korea)
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• v.36 no.6
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• pp.727-732
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• 2012

Baroplastic poly(butyl acrylate) (PBA)/polystyrene (PS) blends were prepared by mixing PBA and PS emulsions synthesized by cationic and anionic surfactant, respectively. Interestingly, the heterocoagulation of nanoparticles have found to be affected strongly by emulsion concentration but the blends have been prepared with almost same compositions regardless of the amount of reactants. Utilizing this method, PBA/PS/Si hybrid nano-blends were prepared successfully via electrostatic attraction forces between PBA, PS and silica nanoparticles. The hybrid nano-blend having 2 or 5 wt% of silica was then processed to a semi-transparent film at $25^{\circ}C$ under 13.8 MPa for 10 min, which showed 3.0 MPa of tensile strength and 25 MPa of elastic modulus. Therefore, the heterocoagulation technique can be used for preparing baroplastics with uniform compositions of polymer and silica nanoparticles.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.149-154
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• 1998

The characteristics of drag reduction and rheological behaviors were investigated using cationic surfactants, whose microstructures are known to change when concentration of the surfactant exceeds CMC. The firstly formed spherical micelles change to rodlike or disklike micelles because of packing between surfactants micells, and of thermodynamic perference. The drag reduction becomes significant when the concentration increases over this micellar transient point. Drag reductions were measured as a function of concentration, and rheological characteristics of the surfactant were further investigated to understand the correlation between their rheological properties and drag reduction. Micelles show the non-Newtonian behavior, and shear thickening behaviors were observed due to the structural development. In addition, structural developments were determined by adding the counter-ion in case of DOBON-G.

• Journal of Adhesion and Interface
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• v.15 no.4
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• pp.151-160
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• 2014

A series of terpolymers based on stearyl methacrylate (SMA), n-methyol acrylamide (n-MAM), and 2-(perfluorooctyl) ethyl acrylate (PFOEA) were synthesized by changing PFOEA contents up to 8 wt% in order to obtain optimal water-repellent properties. In addition, various contents of m-isopropenyl-${\alpha}$,${\alpha}^{\prime}$-dimethylbenzyl isocyanate (TMI) from 1 to 4 wt% were added to the above terpolymers with 4 wt% of PFOEA content. The emulsion polymerization was carried out using tridecyl alcohol (EO)7 (TDA-7) as a nonionic surfactant, alkyl dimethyl amine derivatives (ADAD) as a cationic surfactant, and 2,2'-azobis(2-amidinopropane dihydrochoride) (AAPDL) as an initiator. The synthesized copolymers were characterized by FT-IR spectroscopies, contact angle, surface energy, and water-repellency. Surface and thermal properties were analyzed by SEM, TGA, and DSC. It was found that water repellency increased with increasing the contents of PFOEA and TMI.