브라운 동력학 시뮬레이션에 의한 미세기공에서 단일한 다가전해질 사슬의 제한확산 연구

전명석,곽현욱 한국막학회 2002 멤브레인 Vol.12 No.4

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. The hindered diffusion in confined spaces is an important phenomenon to understand in a micro-scale the filtration mechanism determined by the particle motion in membrane pores. Compared to the case of spherical colloids, both the theoretical investigations and the experiments on the hindered diffusion of polyelectrolytes is actually more difficult, due to lots of relevant parameters resulting from the complicated conformational properties of the polyelectrolyte chain. We have successfully performed the Brownian dynamics simulations upon a single polyeiectrolyte confined in a slit-like pore, where a coarse-grained bead-spring model incorporated with Debye-Huckel interaction is properly adopted. For the given sizes of both the polyelectrolyte and the pore width, the hindered diffusion coefficient decreases as the solution ionic concentration decreases. It is evident that a charge effect of the pore wall enhances the hindered diffusion of polyelectrolyte. Simulation results allow us to make sense of the diffusive transport through the micro-pore, which is restricted by the influences of the steric hindrance of polyelectrolytes as well as the electrostatic repulsion between the polyelectrolytes and pore wall.

Exploring the interactions in binary mixtures of polyelectrolytes: Influence of mixture composition, concentration, and temperature on counterion condensation

De, Ranjit,Lee, Hohjai,Das, Bijan Elsevier 2018 Journal of molecular liquids Vol.251 No.-

<P><B>Abstract</B></P> <P>The counterion condensation in the binary mixtures of like-charged polyelectrolytes with two different molecular weights, where both are negatively charged, has been studied by conductance measurement in aqueous medium. Sodium polystyrenesulfonate with two different chain lengths have been selected as model polyelectrolyte and the investigation has been carried out in the absence of any added salt. The specific conductance-polyelectrolyte concentration data were analyzed in the light of the scaling argument for the conformation of polyion chains in solutions to quantify the fractions of free counterions. Effects of polyelectrolyte concentration, molecular weights of the components of the mixture, and solution temperature on the condensation of counterions have been investigated to explore polyion–counterion interaction, and inter- and intra-chain interactions in these polyelectrolyte mixtures. This investigation revealed that the extent of counterion condensation is significantly influenced by the mixture composition, the polyelectrolyte concentration and the temperature. Evaluation of the polyion transference numbers provided important information as to the direction of the motion of the counterions under the action of the applied electric field.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Counterion condensation in polyelectrolyte (PE) mixtures has been investigated. </LI> <LI> Scaling theory approach has been employed to quantify fraction of free counterions. </LI> <LI> More counterions get condensed in mixtures richer in higher molecular weight PE. </LI> <LI> Counterion condensation grows as the PE concentration and temperature increase. </LI> <LI> Polyion-counterion interactions vary with the composition of the PE mixtures. </LI> </UL> </P>

분자동력학과 몬테카를로의 혼성 분자시뮬레이션에 의한 다가전해질 복잡유체의 미세구조 특성 연구

이현수,전명석 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.5

분자동력학(molecular dynamics)과 몬테카를로(Monte Carlo)의 혼성(hybrid) 알고리즘을 이용하여 harmonic spring 사슬과 하전된 단분자(monomer)들 사이의 Debye-Hu¨ckel potential로 표현된 다가전해질(polyelectrolyte)의 미세구조 특성을 규명하였다. Polyelectrolyte의 단일 사슬에 대해서 기존에 제안된 분자동력학과 몬테카를로의 혼성 알고리즘을 개선하여, polyelectrolyte의 conformation 특성인 끝단거리(end-to-end distance), 선회반경(radius of gyration), 그리고 구조인자(structure factor)를 한층 효율적으로 구할 수 있는 새로운 모사 기법을 개발하였다. 본 연구에서 새로이 개발된 알고리즘에 의한 모사결과와 기존 문헌값과의 비교를 통해 해석 방법의 타당성과 정확성을 검증하였다. 끝단거리와 선회반경간 평균제곱의 비와 구조인자의 계산을 통해, polyelectrolyte 단분자의 하전율(charge fraction)을 대변하는 Bjerrum length λ_β와 용액의 이온화세기에서 결정되어 용매의 screening 정도를 나타내는 Debye length k^-1가 증가함에 따라 사슬이 신장되는 거동을 확인하였다. The microstructural properties of charged polyelectrolytes described by a potential model regarding both the harmonic springs and Debye-Hu¨ckel interaction were investigated by employing a hybrid scheme of molecular dynamics(MD) and Monte Carlo(MC) simulations. Based on the previous hybrid scheme, a novel hybrid scheme has been developed in the present study, with which computational efforts are effectively reduced. We present the conformational properties such as end-to-end distance, radius of gyration and structure factor. It is evident that the simulation results of the present study agree well with the previously reported results. The elongation behavior of the polyelectrolyte chain can successfully be observed by the calculations of the characteristic mean square ratio of end-to-end distance to radius of gyration as well as the structure factor. As the Bjerrum length λ_β and the Debye length k^-1 increase, the polyelectrolyte chain becomes elongated.

형광 공액화 고분자전해질과 DNA 앱타머의 복합체를 사용한 단백질 센서

손지혜,김충호,이택승,Son, Jihye,Kim, Choongho,Lee, Taek Seung 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.6

A water-soluble anionic conjugated polyelectrolyte was successfully synthesized via the Suzuki cross-coupling reaction in the presence of a palladium catalyst. Using this fluorescent polyelectrolyte, a new concept for a rapid, label-free lysozyme-sensing method is proposed via possible naked-eye detection of the emission color change. Intermolecular exciton migration in the conjugated polyelectrolyte-based complex was adopted to enhance the selectivity and sensitivity for lysozyme sensing by the formation and dissociation of the polymer-lysozyme assay complex in the absence and presence of the anti-lysozyme aptamer, respectively. The polymer-lysozyme complex showed red emission because of cooperative aggregation of the conjugated polyelectrolyte and lysozyme. Upon exposure to the aptamer, the complex dissociated into individual molecules, resulting in a transparent blue-emitting solution. This occurred because lysozyme is released from the complex by the aptamer via the more favorable binding between the two molecules (lysozyme and aptamer).

Interactions of nitrates with cationic polyelectrolytes in chelation/ultrafiltration systems for water treatment

Xinsheng Zhu,Hak-Soon Park,추광호 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.6

The interaction between poly(dimethylamine-co-epichlorohydrin-co-ethylene-diamine) with positive charges and nitrate ions in synthetic water was investigated during ultrafiltration (UF). The adsorption behaviour of nitrate onto cationic polyelectrolyte was evaluated with Langmuir and Freundlich isotherms in dilute polyelectrolyte solutions. During UF, ionic strength, Debye–Hu¨ ckel screening length, average electric potentials at the polyelectrolyte interface, and the amount of nitrates adsorbed per mole of polymeric functional groups were estimated at different concentration factors. The results indicated that polyelectrolyte skeletons tended to coil at a higher concentration factor. It was also discovered that adsorbed nitratewas released from the polyelectrolyteswhile making their surface charge more positive at high concentration factors. The coiling of polyelectrolyte chains caused negative effects on the lateral interactions of nitrate with the polyelectrolyte.

Fabrication of uniform hydrogel microparticles with complex polyelectrolyte/silica hybrid thin shells

정은숙,이근주,김진웅 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

We introduced a practical method that allows to provide a mechanically robust hybrid polyelectrolyte/silica thin shell on the uniform hydrogel microparticles. Monodisperse hydrogel particles were fabricated by using the versatile microfluidic technique and consecutive photo-polymerization. Sodium 4-vinylbenzene sulfonate was incorporated to generate negative charges on the hydrogel surface. Then, we coated the hydrogel particles with polyelectrolyte layers by layer-by-layer deposition. Finally a thin silica layer was formed by reduction of silicate on the polyelectrolyte layer. It is expected that these complex hybrid particles have potentials for encapsulation of biomacromolecules and their controlled release.

Theoretical Study for the Separation of Polyelectrolytes by Electrophoresis in the Chromatography

Park, Young G.,Lim, Hwa E. 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.5

Electrophoretic separation was theoretically performed for large polyelectrolytes in the column packed with polymeric gel particles. This paper dealed with the computer simulation based on the Langevin equation of motion and the governing equation for the mass transfer in the presence of an electric field, the theoretical calculation of migration of polyelectrolyte in gel contributed to the understandings of mass transfer in the column. Theoretical studies were investigated in order to establish a relationship providing intraparticle convection effects as a function of an electric field, since a polyelectrolyte quickly orients through the pores of gel in the field direction. Dimensionless transient equations were derived considering mobility for the separation of polyelectrolytes and they were studied by two different dimensionless numbers in the fluid and solid phases in the column, showing how the concentration profiles of polyelectrolyte inside a particle varied in the column according to values of dimensionless number of individual polyelectrolyte. Langevin and governing equations were solved using the numerical method and an operator theory.

Fabrication of Graphene oxide and polyelectrolyte complex hollow capsules

황효찬,허인석,박수영 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Hollow Grahene oxide and polyelectrolyte capsules were produced by using micro fluidics method. In micro fluidics method, oil phase was Quaternized poly(4-pyridine)-b-polystyrene (QP4VP-b-PS) in Chloroform and continuous phase was surfactant. The QP4VP-b-PS droplets put into Graphene oxide solution to fabricate the layer-by-layer by electrostatic interaction. Finally, fabricated hollow capsule by drying inner of the layer-by-layer droplets. Also, fabricated multi layer-by-layer by using other polyelectrolytes. Generally, weak polyelectrolyte depends on pH. Hollow capsule expected pH responsibility because of weak polyelectrolyte.

Fabrication of polyelectrolyte-derived versatile liquid transporter for sustainability

김유진,오석민,김은미,장재형 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

Nature is a valuable source of inspiration for the development of new structures in pursuit of sustainability. Diverse organisms in nature, such as eggs, have a biodegradable multi-layer that surrounds the liquid core. Here, we developed a concentric polymer capsule to create an outstanding membrane capable of encapsulating liquid formulations that can be applied as a sustainable container tool. A polyelectrolyte- derived dynamic membrane can induce a multilayer that exhibits pH-responsive characteristics, protecting internal nutrients against external acidic pH and promoting rapid disassembly by exposure to basic pH. Moreover, the remarkable coacervate induced properties of the capsules demonstrated their great potency to be utilized as versatile scaffolds in biomedical applications.

Ionic charge-selective electron transfer on self-assembled polyelectrolyte-modified ITO electrode

Yun-Ho Kim,Gangri Cai,이원주,Kyung-Hee Hyung,조병원,이중기,한성환 한국물리학회 2009 Current Applied Physics Vol.9 No.11

We report the observation of the ionic charge-selective electron transfer on the polyelectrolytes-modified indium–tin oxide (ITO) electrode. The polyelectrolytes multilayers are formed on ITO by a layer-by-layer deposition of polyethyleneimine (PEI) and polyacrylic acid (PAA). Indium oxide of the ITO surface provides adsorption sites to the amine functional groups to form stable polyelectrolyte layers on ITO. Then, PAA layers and multilayers of both polyelectrolytes are successfully constructed on ITO. The charge of the top layers controls the electron transfer from the electrode to the redox species in solution. The PEI-modified electrodes at the top layers have positive charges and good affinity toward negatively charged complex, Fe(CN)3- 6 . Whereas, the PAA-modified electrodes at its top layers has negative charges and demonstrates good affinity toward positively charged complex, Ru(NH3)3- 6 . The coulombic charge interaction critically controls the electron transfer at the liquid–solid interface.