• Polymer(Korea)
• /
• v.25 no.5
• /
• pp.754-758
• /
• 2001

In order to use vesicle as a space of polymerization, monomer and cross-linking agent were put into hydrophobic part of vesicle. The vesicle solution of dimethyldioctadecylammonium bromide was formed by ultrasonication. Styrene and divinylbenzene were put into this solution and polymerization was conducted by adding AIBN. The polymer with sphere-shaped structure was obtained by removing all of the surfactant by extraction of ethanol And using methyl methacrylate and ethylene glycol dimethacrylate, this sphere-shaped polymer structure was also formed.

• Macromolecular Research
• /
• v.15 no.2
• /
• pp.154-159
• /
• 2007

Polyaniline (PANI) nanospheres, 4 run in diameter, were fabricated by the microemulsion polymerization of octyltrimethyl ammonium bromide (OTAB). The size of the PANI nanoparticles could be controlled as functions of the surfactant concentration, surfactant spacer length and polymerization temperature. The diameter of the PANI nanospheres decreased with increasing surfactant concentration and decreasing temperature. The PANI nanoparticles revealed enhanced conductivity compared to conventional bulk PANIs. In addition, the PANI nanoparticles could be applied as optically transparent conducting materials due to their high conductivity and the nanosize effect. With 9 wt% PANI in the PC matrix, the PANI/PC film exhibited a conductivity of $8.9\times10^{-3}S/cm$ and transparency exceeding 95% over the entire visible light range.

• Macromolecular Research
• /
• v.15 no.1
• /
• pp.51-58
• /
• 2007

The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

• Polymer(Korea)
• /
• v.28 no.5
• /
• pp.374-381
• /
• 2004

Gas permeability of low density polyethylene (LDPE) film containing zeolite powder for $CO_2,\;O_2$ and $N_2$ were investigated. Zeolite powders modified by cations or surfactant were compounded with LDPE to produce $20 wt\%$ masterbatch. After blending the masterbatch with LDPE, zeolite filled films were prepared by the blown film process. Finally, the composite films containing zeolite loadings of 0, 3,5, and $10 wt\%$ were produced. A gas permeability apparatus based on the variable volume principle was designed to analyze the characteristics of films. Experiments showed a general trend that gas permeabilities first decreased and then increased as the zeolite content was increased. Surfactant modified zeolite showed a better interfacial adhesion with the matrix, but the film did not show a discernible difference in gas permeability compared with the other modified films. The difference of temperature dependences in the gas permeabilities of composite films was slightly smaller than that of LDPE film.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.416.1-416.1
• /
• 2002

Biodegradable PLGA microspheres(MS) have been widely studied for delivering antigens because PLGA has the characteristics of various degradation rate. In general. since MS have shown potential for single-dose vaccines. the degradation rate of PLGA is determined by their molecular weight. polymer composition, etc. We studied the influences of molecular weight of PLGA. polymer composition and surfactant on in vitro release and in vivo effects. (omitted)

• Macromolecular Research
• /
• v.17 no.12
• /
• pp.943-949
• /
• 2009

A highly dispersed W/O emulsion of silicone oil (cyclomethicone)/water system was prepared with a nonionic surfactant. The surface and interfacial tension between the oil and water were characterized in terms of the droplet size distribution and viscosity change of the emulsion. When the dispersed phase concentration was relatively high, the viscosity of the emulsion was rapidly increased and the droplet size of the emulsion was decreased. The rheological behavior of the emulsion system showed non-Newtonian and shear thinning phenomena depending upon the content of the dispersed phase. The droplet size of the emulsion was decreased with increasing surfactant content and water concentration. The relative viscosity of the emulsion was better predicted with the Choi-Schowalter model than with the Taylor model. The value of the complex modulus increased with increasing surfactant concentration. The linear viscoelastic region was expanded with a dispersed phase concentration. According to the change in the viscosity, the behavior was classified into three distinct regions: [I] linear viscoelastic, [II] partially viscoelastic, and [III] viscous. The creep/recovery behaviors in each region were characterized.

• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.523-530
• /
• 1999

Acrylic pressure-sensitive adhesive has been made utilizing organic solvents, but nowadays it is made by solvent-free system due to environmental problems. In this study, emulsion polymerization were carried out at $40^{\circ}C$ with methacrylic acid(MAA), n-butyl acrylate(n-BA) and 2-ethylhexyl acrylate(2-EHA) as monomers in the presence of anionic(sodium dodecyl sulfate, SDS) and nonionic(ethylene oxide types) surfactant mixtures. The overall conversion of the polymerization reaction in a mixed surfactant system was found to be higher than that in a single surfactant system. Emulsion stability in mixed or anionic surfactant systems was found to be over 12 week, which was better than that in nonionic surfactant system. Emulsion particle size decreased as surfactant content increased. The Tg and molecular weight of emulsion polymer were inependent of the type, the amount and the mixing ratio of surfactant. Based on the results of stability and peel strength, the optimum nonionic surfactant ratio in total 4 g of surfactant mixture systems is found to be 40~60% by weight where the nonionic surfactant has 50 ethylene oxide groups and 16~18 carbon atoms in hydrophobic alkyl chain.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.876-880
• /
• 1999

The surfactant self-diffusion coefficients of mixed micellar solutions of ionic and nonionic surfactants have been measured by the NMR pulsed field gradient spin echo(FT-PGSE) method. In addition, the line widths of $^1H$ NMR signal have been monitored. The system investgated are $C_{12}EO_5/SDS/D_2O$, $C_{12}EO_5/DTAC/D_2O$, and $C_{12}EO_8/SDS/D_2O$. In the sample series, the molar ratios of $D_2O$ to surfactant(ionic+nonionic) were kept constant while the surfactant mixing ratio was varied. For the $C_{12}EO_5$ system, the surfactant self-diffusion coefficient indicates minimum when the surfactant mixing ratio is about 20% ionic surfactant. The observed decrease in self-diffusion coefficients as nonionic surfactant was replaced by ionic surfactant is interpreted to mainly be due to an increased micelle-micelle repulsion. The increase in self-diffusion coefficients occurring at higher fraction of ionic surfactant is shown to be due to a decrease in micelle size. For the $C_{12}EO_8$ system, the effect of the surfactant mixing ratio is much weaker which can be understood by considering the molecular geometry and large headgroup area. The proton NMR line widths correlate well with the self-diffusion coefficients and broadening of the alkyl chain methylene signals is found when the self-diffusion coefficients is low.

• Elastomers and Composites
• /
• v.35 no.1
• /
• pp.19-28
• /
• 2000

The fundamental study of additional silicone impression material has been performed by comparing the other import products. In order to estimate the possibility of usage of the impression material developed in this study, the several techniques such as IR, EDX, DSC, TGA, rubber rheometer, and contact angle measurement were used. According to the results, there were not any product satisfying all properties required in the impression material. The impression material developed in this study showed best mechanical properties among the all impression materials. However. the wetting property should be studied more by an introduction of a hydrophilic surfactant or modification of a base polymer.

• Polymer(Korea)
• /
• v.28 no.2
• /
• pp.154-161
• /
• 2004

Modified poly(4-vinylpyridine) was obtained by partial quarternization of nitrogen atoms in pyridine rings of poly(4-vinylpyridine) with methyl group. By means of laser light scattering and fluorescence, it was found that this modified polymer chains were aggregated in the aqueous solution and its structure was core-shell type. The hydrophobic parts of the chains were densely condensed in core part and the hydrophilic part of quarternized amino with positive charge formed the shell part. In the mixed system of modified poly(4-vinylpyridine) and anionic surfactant, sodium dodecyl sulfate, it was observed that a critical aggregation concentration existed and that this critical concentration was suddenly decreased above 0.1 M NaCl. The size change of aggregates was also investigated by dynamic light scattering while sodium dodecyl sulfate was added into polymer solution upto the critical aggregation concentration.