• Membrane Journal
• /
• v.23 no.2
• /
• pp.112-118
• /
• 2013

Polyancrylonitrile nanofiber membrane (PAM) was prepared by using the electrospinning method with a solution of polyacrylonitrile (PAN) in DMF. The pore-diameter of PAMs and the number of PAM's layer were controlled for the microfiltration (MF) application. In addition, in order to improve the water-flux, AN-PEGMA copolymers have been synthesized via free radical polymerization with poly (ethylene glycol) methyl ether methacrylate and azobisisobutylronitrile (AIBN), and then PAN/AN-PEGMA nanofiber membranes (PAM/APM) were prepared by electrospinning with a mixture of PAN (9 wt%) and AN-PEGMA (3 wt%) in DMF (88 wt%). The prepared membranes were investigated with FT-IR and E.D.S. It was confirmed through scanning electron microscope (SEM), porometer, and porosity analysis that the porous membrane with a uniform diameter (400~600 nm) and a uniform pore characteristics (0.5~0.4 ${\mu}m$) was prepared. For the MF application, water-flux measurements were investigated and then the result was shown that the water permeability value of PAM/APMs introduced AN-PEGMA copolymers was relatively higher than that of the PVdF commercial membrane. From these results, PAN nanofiber membranes prepared by electrospinning could be utilized as a MF membrane.

• Journal of the Korean Chemical Society
• /
• v.60 no.3
• /
• pp.181-186
• /
• 2016

The hydrophilic ophthalmic lens with addition of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA) and Ag nanoparticles were manufactured. And also, the cross-linker ethylene glycol dimethacrylate (EGDMA) and the initiator azobisisobutyronitrile (AIBN) were used for polymerization. The polymerization of the hydrogel lens material was conducted through thermal polymerization in 100 ℃ for 1h. The optical and physical characteristics of hydrogel lens were evaluated by measuring water content, refractive index and optical transmittance. The water content of sample containing HEA, HEMA and HPMA was in the average of 82.12%, 37.06% and 21.57%, respectively. And also, refractive index of the sample containing HEA, HEMA and HPMA was in the average of 1.3540, 1.4330 and 1.4649, respectively. In case of the optical properties of the sample, the results showed that the near-UV transmittance was 82.67%, 80.32% and 79.83%, and the visible transmittance was 89.72%, 88.24% and 86.89%, respectively. And also, optical transmittance of the sample containing Ag nanoparticles showed that the near-UV transmittance of 10.59% and visible transmittance of 43.74% were obtained. From the results, the molecular length influenced on the water content and refractive index of the polymerized material.

• Polymer(Korea)
• /
• v.30 no.6
• /
• pp.505-511
• /
• 2006

We tried to prepare polystyrene composite particles containing carbon black by suspension polymerization with water as a reaction medium. Hydrophobic silica was selected as a stabilizer and oil-soluble azobisisobutyronitrile (AIBN), as an initiator. All polymerization reactions were carried out at a fixed temperature of $75^{\circ}C$. Stabilizer concentration was varied from $0.17{\sim}3.33wt%$ compared to water, where particles with $7.96{\mu}m$ in average diameter were obtained at 1.57 wt% of stabilizer. Increase in divinylbenzene concentration, as a crosslinking agent, from $0.1{\sim}1.0 wt%$ compared to monomer exhibited a large increase in average particle diameter Incorporation of 1wt% of carbon black compared to monomer produced an increase in average diameter It is speculated that viscosity lower than that necessary to induce even dispersion of carbon black particles led to poor dispersion, and as a result, large particles. For a styrene mixture containing 3 wt% carton black compared to monomer, enhanced dispersion due to an increase in carbon black concentration reduced average particle diameters. For styrene mixtures containing 1 and 3 wt% carbon black compared to monomer, preparticles before polymerization and polymer composite particles after polymerization showed a similar tendency towards particle formation. When carbon black concentration compared to monomer was increased to 5 and 7 wt%, styrene mixtures exhibited a large increase in viscosity and thus better dispersion of carbon black particles, which led to a decrease in preparticle diameters. However, these particles experienced agglomeration in the polymerization process, and polystyrene composite particles increased in average diameter.

• Elastomers and Composites
• /
• v.40 no.3
• /
• pp.188-195
• /
• 2005

Chemical and physical changes and the contents of functional groups in the carbon black surface after the ozone treatment was investigated using elemental analysis, pH, tint strength, DBP, $N_2SA$, IA, and acid-base reaction. As the treatment time was increased, surface structure, particle size and surface area of carbon black did not change, while surface oxygen contents increased, and pH decreased and then saturated after $1{\sim}2$ hour. The contents of carboxylic, lactone, hydroxyl, and carbonyl groups were analyzed with four bases such as $NaHCO_3,\;Na_2CO_3,\;NaOH$, and $NaOC_2H_5$. Before oxidation, the carbonyl group was dominantly present on the surface, but by increasing the treatment time, the contents of the carboxylic and carbonyl groups increased to a saturated level after $1{\sim}2$ hour. Before and after the oxidation, the lactone and hydroxyl groups were nearly absent. These results showed that the reaction mechanism of carbon black and ozone is similar to that of ethylene and ozone. Weight of oxidized carbon black was increased after treating AIBN, while free radical was slightly decreased by ESR analysis. When carbon black was treated with organic compounds containing mercapto- groups, the results of ESR showed that free radical peak intensity was almost diminished compared to original carbon black.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.4
• /
• pp.437-443
• /
• 2015

Purpose: This study evaluated the optical and physical and characteristics of soft contact lens polymerized with addition of 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid in the basic hydrogel contact lens material. In particular, the utility of 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine- 4-carboxylic acid as a hydrogel contact lens material was investigated. Methods: In this study, 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid were used as additives. Also, 2-hydroxyethyl methacrylate, acrylic acid, methyl methacrylate and a cross-linker EGDMA were co-polymerized in the presence of AIBN as an initiator. Results: The physical properties of the produced polymers were measured as followings. The water content of 34.54~37.15%, refractive index of 1.4320~1.4342, tensile strength of 0.2872~0.3608 kgf and contact angle of $57.82{\sim}79.57^{\circ}$, UV-B transmittance of 76.8~82.4% and UV-A transmittance of 84.6~86.6% were obtained respectively. Conclusions: Based on the results of this study, contact lens material containing 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid is expected to be able to used as a material for high wettability and UV-block hydrogel contact lens.

• Composites Research
• /
• v.35 no.2
• /
• pp.115-119
• /
• 2022

The performance of carbon fiber is important for the production of these high-quality polymer composite materials such as CFRP (Carbon Fiber Reinforced Plastic). For this purpose, it is essential to use an optimized spinning process for improving the mechanical, physical, and structural properties of the precursor fiber, which greatly affects the properties of the carbon fiber, and the use of a suitable precursor polymer. In this study, the content of MAA (Methacrylic Acid), MAA injection time, and concentration of AIBN (2,2'-Azobis(2-methylpropionitrile)) were set as parameters for the polymer synthesis process, and Poly(AN-co-MAA) (poly(acrylonitrile-co-methacrylic acid)) was polymerized by solution polymerization. Poly(AN-co-MAA) with a molecular weight of 305,138 g/mol and an MAA ratio of 4.2% was dissolved in DMF (N,N-dimethylformamide) at a concentration of 16.0 wt%, and then a precursor fiber was prepared through dry-jet-wet spinning. The precursor fiber had a tensile strength of ~1.06 GPa and a tensile modulus of ~22.01 GPa, and no voids and structural defects were observed on the fiber.

• Applied Chemistry for Engineering
• /
• v.21 no.1
• /
• pp.34-39
• /
• 2010

Methacryloxypropyltrimethoxysilane (MPTMS) was used for the surface modification of silica nanoparticles in the toluene dispersion system for 8 h (MPSN). Then, methacryloxypropyl-modified silica nanoparticles were successfully prepared by solutioun polymerization in the ethanol solution at $60^{\circ}C$ for 14 h with adding AIBN initiator. The modification of ultra-fine particles (SiOx-PAA nanospheres) was investigated via EA, XPS, FTIR, TGA, SEM and TEM. The mean diameter of the bare silica nanoparticles, MPSN and SiOx-PAA monodisperse nanoparticles was about 25, 30 and 35 nm, respectively.

• Journal of the Korean Society of Visualization
• /
• v.9 no.4
• /
• pp.41-46
• /
• 2011

Oxygen sensitive functional particles(OSParticle) were fabricated by three different methods for using the particles as oxygen sensors and PIV tracers. The used methods were a physical coating method, an ion-exchange method and a dispersion polymerization method. The physical coating method is dipping $SiO_2$ hollow particles into dye solution then drying. This method is very simple, but particles are not uniform in diameter and luminescence. The particles fabricated by the ion-exchange method have very uniform diameter and well doped. However, it can not be used in water since the particles are hydrophobic. In case of the dispersion polymerization method, the diameter of OSParticles is quite uniform. The diameter of OSParticles can be changed by controlling the quantity of AIBN (2,2'-azobis isobutyronitrile). For the purpose of dissolved oxygen concentration measurement in micro scale water flows, the dispersion polymerized OSParticles turn out to be the most superior functional particles. The luminescent intensity of OSParticles was tested with the variation of dissolved oxygen concentration in water samples. As a result, the luminescent intensity of OSParticles is monotonically decreased with increasing DO (Dissolved oxygen) concentration of water.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.8
• /
• pp.1549-1553
• /
• 2008

A molecular imprinted polymer (MIP) using (+)catechin ((+)C) as a template and acrylamide (AM) as a functional monomer was prepared. Acetonitrile was used as the porogen with ethylene glycol dimethacrylate (EGDMA) as the crosslinker and 2,2'-azobis(isobutyronitrile) (AIBN) as the initiator. The adsorption isotherms in the MIP were measured and the parameters of the equilibrium isotherms were estimated by linear and nonlinear regression analyses. The linear equation for original concentration and adsorpted concentrations was then expressed, and the adsorption equilibrium data were correlated into Langmuir, Freundlich, quadratic, and Langmuir Extension isotherm models. The mixture compounds of (+)C and epicatechin (EC) show competitive adsorption on specific binding sites of the (+)catechin-MIP. The adsorption concentrations of (+)C, epicatechin (EC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG), on the (+)catechin-molecular imprinted polymer were compared. Through the analysis, the (+)catechin-molecular imprinted polymer showed higher adsorption ability than blank polymer which was synthesized molecular imprinted polymer without (+)catechin. Furthermore, the competitive Langmuir isotherms were applied to the mixture compounds of (+)C and EC.

• Proceedings of the IEEK Conference
• /
• 2004.08c
• /
• pp.675-679
• /
• 2004

The existing conjugated blue emitting material polymer which has been used for the two-wavelength method white-emission has good stability and low operating voltage as merits, but the imbalanced carrier transport has been indicated as problem area. We have introduced a novel blue emitting material having perylene moiety unit with hole transporting ability and blue emitting property and triazine moiety unit with electron transporting ability into the same host chain. We have synthesized N-[p-(perylen-3-y1)pheny1]methacry1 amide (PPMA) monomer and [N-(2,4-dipheny1-1,3,5-triazine)pheny1 methacry1 amide] (DTPM) monomer having blue light-emitting unit and electron transport unit, respectively by three steps. A novel non-conjugated blue emitting material Poly[N -[p­(perylene-3-y1) pheny1] methacry1 amide-co-N-[P-(4,6-dipheny1-1,3,5-triazine-2-y1]pheny1]methacry1 amide] (PPPMA-co-DTPM) copolymer having electron transporting unit was synthesized by the solution polymerization of PPMA and DTPM monomers with an AIBN initiator and showed high yield of $75{\%}$. It was very soluble in common organic solvents, and the fabrication of the thin film using a spin coating method was very simple. The PPPMA exhibited a good thermal stability.