• 상하수도학회지
• /
• 제18권5호
• /
• pp.608-618
• /
• 2004

Since polyelectrolytes have been used as conditioners, conventionally only a single polyelectrolyte has been added for sludge conditioning. However, the amount of polyelectrolyte needed for optimal conditioning of sludge is very critical. Overdosing reduces the sludge dewaterbility. In this experimental study, sludge conditioning with single or dual polyelectrolyte was conducted to avoid problems associated with overdosing. Single polyelectrolyte conditioning was conducted by one of cationic, nonionic, and anionic polyelectrolytes. The dual polyelectrolyte conditioning was performed by adding one polyelectrolyte and another one in sequence. The dewaterbility of sludges were measured by SRF(specific resistance to filtration), TTF(time to filter), CST(capillary suction time) respectively. Additionally, parameters such as turbidity, zeta potential, viscosity of conditioned sludges or supematant were measured to evaluate the changed characteristics of sludge by addition of polyelectrolytes. From the experiment results, it was concluded that single polyelectrolyte conditioning had a high probability of overdosing, whereas dual polyelectrolyte conditioning resulted in a better dewaterbility and less chance of overdosing. But, it was also found that dosing sequence in dual conditioning was very important according to the characteristics of sludge. Parameters such as viscosity, turbidity, zeta potential were found to be useful as a means of evaluating sludge dewaterbility.

• 멤브레인
• /
• 제12권4호
• /
• pp.207-215
• /
• 2002

한정된 미세공간에서의 제한확산(hindered diffusion)은 멤브레인 기공(pore)에서 입자들의 운동에 의해 결정되는 여과 메카니즘을 매우 미세한 수준에서 이해하는데 중요한 현상이다. 구형(spherical) 콜로이드 입자에 비해 보다 복잡한 형태(conformation)인 고분자사슬 구조를 갖는 다가전해질(polyelectrolyte)의 제한확산 거동에는 다양한 인자들이 관련되어 있기 때문에, 이론 접근은 물론 실험적 접근도 한층 어려운 것이 사실이다. 본 연구에서는, 슬릿형 미세기공에 한정되어 있는 단일한 다가전해질(single polyelectrolyte)에 coarse-grained bead spring model과 먼거리(long-range) 정전상호작용(electrostatic interaction)인 Debye-Huckel potential을 적용하여 분자시뮬레이션 기법인 브라운 동력학 모사를 수행하였다. 기공과 다가전해질 사슬(Polyelectrolyte chain)의 주어진 크기에서, 용액의 전해질 이온농도가 감소함에 따른 사슬의 신장(extension)효과는 제한확산계수를 감소시켰고, 기공 벽면의 하전성은 제한확산계수를 더욱 감소시켰다. 이는, 다가전해질 사슬(polyelectrolyte chain)의 입체적 장애(steric hindrance)와 함께 정전반발력이 미세기공에서의 확산이동을 억제함을 의미한다.

• KSBB Journal
• /
• 제24권6호
• /
• pp.515-520
• /
• 2009

This study presented facile method of cell patterning using fabricated PDMS patterns on polyelectrolyte coated surface. This basic principle is the fabrication of functional surface presenting two orthogonal surfaces such as cell adhesive and repellent properties. Cell adhesive surface was firstly fabricated with simple coating of polyelectrolyte multilayer. And then, the desired patterns of PDMS for the prevention of nonspecific binding of cells were transferred onto the previously formed thin film of polyelectrolyte multilayer. Thus, we could prepare novel functional surface simultaneously containing PDMS and polyelectrolyte region. As expected, the PDMS regions showed effective prevention of nonspecific binding of cell and the other region, exposed polyelectrolyte area, provided cell adhesive environment. The height of formed PDMS structure was about 100 nm. Based on this method, cell patterning can be successfully obtained with various pattern shapes and sizes. Therefore, we expect that this simple method will be useful platform technology for the development of cell chip, cell based assay system, and biochip.

• Macromolecular Research
• /
• 제16권4호
• /
• pp.373-378
• /
• 2008

A simple chemical fixation method for the fabrication of layer-by-layer (LbL) polyelectrolyte multilayer (PEM) has been developed to create a large area, highly uniform film for various applications. PEM of weak poly-electrolytes, i.e., polyallylamine hydrogen chloride (PAH) and poly(acrylic acid)(PAA), was assembled on polymer substrates such as poly(methyl methacrylate)(PMMA) and polycarbonate (PC). In the case of a weak polyelectrolyte, the fabricated thin film thickness of the polyelectrolyte multilayers was strongly dependent on the pH of the processing solution, which enabled the film thickness or optical properties to be controlled. On the other hand, the environmental stability for device application was poor. In this study, we utilized the chemical fixation method using glutaraldehyde (GA)-amine reaction in order to stabilize the polyelectrolyte multilayers. By simple treatment of GA on the PEM film, the inherent morphology was fixed and the adhesion and mechanical strength were improved. Both surface tension and FT-IR measurements supported the chemical cross-linking reaction. The surface property of the polyelectrolyte films was altered and converted from hydrophilic to hydrophobic by chemical modification. The possible application to antireflection coating on PMMA and PC was demonstrated.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1422-1424
• /
• 2009

Modified self-assembled $TiO_2$ and polyelectrolyte multilayer film have been used as OTFT insulator. Both films were used as gate insulator and their thickness were reduced to the order of 10nm. The operating voltage of OTFT was substantially reduced due to nanoscale thickness of titanium oxide and polyelectrolyte multilayer. Pentacene-based OTFT characteristics will be discussed.

• Korean Membrane Journal
• /
• 제10권1호
• /
• pp.39-45
• /
• 2008

Polyelectrolyte complex based on two anionic polysaccharides, composed of sodium alginate and carrageenan, were prepared by interacting with divalent calcium ions in solution. The effects of annealing on the structural deformation of polyelectrolyte complex and on their characteristics at removing water from a methanol mixture from the point of molecular sieve were investigated and discussed. The result showed that the structural deformation of the annealed polyelectrolyte complex has an effect on the free volume between these polymer chains and the chelate segments such a shrinking of the overall morphology, which act as a molecular sieve in the separation of methanol and water mixtures.

• Macromolecular Research
• /
• 제10권6호
• /
• pp.297-303
• /
• 2002

We have investigated the microstructural properties of a weakly charged polyelectrolyte modeled with both Hookean spring and Debye-Huckel potential, by employing a novel hybrid scheme of molecular dynamics (MD) and Monte Carlo (MC) simulations. Although the off-lattice pivot step facilitates the earlier computations stage, it gives rise to oscillations and hinders the stable equilibrium state. In order to overcome this problem, we adopt the MC off-lattice pivot step in early stage only, and then switch the computation to a pure MD step. The result shows that the computational speed-up compared to the previous method is entirely above 10 to 50, without loss of the accuracy. We examined the conformations of polyelectrolyte in solvents in terms of the end-to-end distance, radius of gyration, and structure factor with variations of the screening effects of solvent and the monomer charges. The emphasis can favorably be given on the elongation behavior of a polyelectrolyte chain, with observing the simultaneous snapshots.

• Macromolecular Research
• /
• 제8권1호
• /
• pp.26-33
• /
• 2000

A series of pH/temperature sensitive polymers were synthesized by copolymerizing N-isopro-pyl acrylamide(NIPAAm) and acrylic acid(AAc) . The influence of polyelectrolyte between poly(allyl amine) (PAA) and poly(L-lysine)(PLL) on the lower critical solution temperature(LCST) of pH/temperature sensitive polymer was compared in the range of pH 2∼12. The LCST of PNIPAAm/water in aqueous poly(NIPAAm-co-AAc) solution was determined by cloud point measurements. A polyelectrolyte complex was prepared by mixing poly(NIPAAm-co-AAc) with poly(allyl amine) (PAA) or poly(L-lysine) (PLL) solutions as anionic and cationic polyelectrolytes, respectively. The effect of polyelectrolyte complex formation on the conformation of PLL was studied as a function of temperature by means of circular dichroism(CD). The cloud points of PNIPAAm in the aqueous copolymers solutions were stongly affected by pH, the presence of polyelectrolyte solute, AAc content, and charge density. The polyelectrolyte complex was formed at neutral condition. The influence of more hydrophobic PLL as a polyelectrolyte on the cloud point of PNIPAAm in the aqueous copolymer solution was stronger than that of poly(allyl amine)(PAA). Although polymer-polymer complex was formed between poly(NIPAAm-co-AAc) and PLL, the conformational change of PLL did not occur due to steric hinderance of bulky N-isopropyl groups of PNIPAAm.

• 펄프종이기술
• /
• 제41권4호
• /
• pp.65-72
• /
• 2009

We investigated the effect of polyelectrolyte types in Layer-by-Layer multilayering and furnish combination on physical properties of paper. Handsheets were made from pulp fibers with different polyelectrolytes composition, and their density, formation, tensile strength, strain, tear strength and burst strength were evaluated. The density of handsheet was slightly decreased by polyelectrolyte multilayering. Formation did not show a significant change, but all mechanical properties were increased by polyelectrolyte multilayering. Remarkable improvement in tensile and tear strengths was obtained when pulp fibers were treated with cationic starch and poly styrene 4-sulfonate. Irrespectively of final ionicity of pulp fiber, tensile index, strain and tear strength of paper could be improved simultaneously by polyelectrolyte multilayering.

• 펄프종이기술
• /
• 제40권3호
• /
• pp.15-22
• /
• 2008

Properties of pulp fibers can be modified by LbL multilayering technology. We evaluated the effect of stock composition on the polyelectrolyte multilayering performance of pulp fibers in this study. Stock composition was varied with pulp type and fines content. Three types of pulp-Hw-BKP, BCTMP and KOCC-were treated with polyelectrolytes of poly-DADMAC and PSS. Fines content of stock were controlled at 0, 10, 20, 30, and 40%. Zeta potential of pulp fibers and charge demand of filtrate were evaluated. The highest adsorption ratio was obtained for BCTMP because of its shortest fiber length and highest specific surface area. Higher fines content in the stock increased the adsorption ratio of polyelectrolyte onto pulp fiber and it required a higher amount of polyelectrolyte for charge neutralization. For the pulp stock with higher fines content, a higher level of polyelectrolyte and the increased layer number were required to modify and stabilize the electrochemical properties of pulp fibers.