On the theory of weakly charged polyelectrolytes

The problem of the possible regimes of the qualitatively different behaviour of solutions of weakly charged polyelectrolytes in theta- and good solvents are considered. For both cases we constructed the diagram of states with the following variables: polymer concentration in solution and concentration of added low-molecular weight salt. We also describe the behaviour of a polyelectrolyte solution in each of the regimes. To obtain the diagram of states it was necessary to solve the problem of the Debye-Hückel screening by non-point-like objects. This problem is considered in the Appendix.     

Copolymerization of ethene and dimethanooctahydronaphthalene with aluminoxane containing catalysts

With homogeneous catalysts on the basis of chiral metallocenes and methylaluminoxane it has become possible to polymerize cyclic olefins like cyclobutene, cyclopentene, norbornene, or dimethanonaphthalene (DMON). No ring opening reaction occurs. The crystalline polycycloalkenes show extremely high melting points between 400 and 600°C. Copolymers of DMON with ethene are amorphous. They have molecular weights between 50000 and 150000 and high glass transition points up to 160°C. These copolymers could be used as materials for optical discs and fibers.     

Oscillatory shear rheology of dilute solutions of flexible polymers interacting with oppositely charged particles

Fluids with both attractions and repulsions among its constituents can exist in multiple states depending on nature of the interactions. An external flow can induce such systems to transition between the different states, such as the globule‐stretch transition for polymers in poor solvents. Brownian dynamics simulations of a dilute solution of polymers and colloids interacting via short‐ranged potentials are presented. For some values of the strength and range of interactions, compact structures of polymers and colloids are formed. An external flow is capable of pulling these globules apart, causing the polymers to stretch at a critical shear rate. In oscillatory shear, the shear rate can cycle between being above and below this critical shear rate leading to interesting dynamics. These dynamics are quantified using the rheological response in large amplitude oscillatory shear. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1365–1371, 2014     

Adhesion of charged particles

The adhesion properties of charged particles are of considerable importance in the electrophotographic process. Measurements on irregularly-shaped, pigmented particles, called toner in the electrophotographic industry, show that adhesion increases with toner charge but that the magnitude is much larger than expected from a simplified electrostatic image force model. An enhanced electrostatic adhesion is also seen in electric field detachment measurements on spherical charged particles. In both cases, this unexpected large adhesion can be attributed to a nonuniform distribution of charge on the surfaces of the particles.     

Flocculation by cationic polyelectrolytes: Relating efficiency with polyelectrolyte characteristics

A series of acrylamide/dimethylaminoethylacrylate methyl chloride copolymers (AM‐co‐DMAEA) was evaluated as flocculants for model Precipitated Calcium Carbonate (PCC) in distilled water. These cationic polyelectrolytes (PEL) differed by their AM/DMAEA ratio, i.e., their charge density, chain architecture (linear and branched), their intrinsic viscosity (IV), and zeta potential of their aqueous solutions. The IV being directly related to the hydrodynamic volume of the PEL and the zeta potential reflecting the effective charges in suspension were selected for practically useful correlations with flocculation performance. The fractal dimension (d_F) and the scattering exponent (SE) of the flocs, analyzed by the laser diffraction method, were taken as indication of primary particle and aggregate assembly. For the optimum PEL dosage, SE and d_F varied with the IV and zeta potential. It was observable that floc size, floc resistance, and floc reorganization correlate with the PEL characteristics. Copolymers with lower IV, which is here associated with PEL of similar molar mass but lower charge density, yielded larger and less resistant flocs. Copolymers with higher IV originated smaller more compact flocs being more resistant. In high shear situations, where floc breakage should be avoided, as it is the case in papermaking, polymers with high IV yielding large SE are advantageous. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dynamics and microstructure of charged soft nano-colloidal particles

The microstructure and rheological properties of swellable nano-particles consisting of cross-link methacrylic acid/ethyl acrylate were examined using dynamic light scattering (DLS) and rheological techniques. A unified semi-empirical approach for predicting the viscosity of dilute and concentrated systems was proposed, where a variable specific volume, k was introduced to convert the mass concentration to effective volume fraction. The viscosity data for four different microgel systems showed excellent agreement with the modified Krieger-Dougherty model. The parameters, c₀ and m for the expression, k−k_min/k₀−k_min=[1+(c/c₀)²]^−m as a function of degree of neutralization (α) were determined. We observed that c₀ decreases with α, while m increases with α. The validity of the new approach was compared against the theoretical model for determining the effective volume fraction, and excellent agreement was observed.     

Transfer characterization of charged particles through charged conductive membrane via dialysis process

In this work the effects of applied electrical charge on mechanism and transfer rate of charged particles through conductive membrane have been elucidated. Another individual parameter which plays a vital role in assigning mechanism and rate of transport is absolute concentration. This is independent from the effect of concentration gradient which is the driving force for mass transfer. In the experimental section, the transfer of sodium dodecyl sulphate (SDS) micelles through charged membrane was investigated. The membrane consisted of a commercial microfiltration (GVHP) membrane as the support coated with a conductive polymer i.e. polypyrrole. A wide range of electrical charges (voltages) were applied on the surface of the conductive membrane. The electrical charge qualitatively and quantitatively influences the mass transfer rate. The difference between transport mechanisms of charged particles at low and high concentrations is more evident in the presence of electrical surface charge. In summary, initial feed concentration, electrical charge and their interactions affect the transport rate and mechanism.     

Attapulgite@polymer particles with double‐layer polymer shell via soapless seeded emulsion polymerization

Attapulgite needle encapsulated with double‐layer polymer shell (ATP@DP) were prepared by the soapless seeded emulsion polymerization of the second monomer styrene in the dispersion of the attapulgite needle encapsulated with poly(methyl methacrylate) (ATP@PMMA), which was also conducted by the soapless seeded emulsion polymerization of the first monomer methyl methacrylate with the cetyltrimethylammonium bromide (CTAB) modified attapulgite needle (org‐ATP) as seeds. The different morphologies of ATP, ATP@PMMA particles, and ATP@DP particles were characterized by transmission electron microscopy, and the encapsulation mechanism was also discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of well‐defined poly(vinyl ether)‐based macromonomers having pendant glycerols via living cationic polymerization and their application to the preparation of core−shell polymer particles

A new vinyl ether monomer bearing a glycerol pendant moiety protected with an isopropylidene group (2‐(2,2‐dimethyl‐[1,3]dioxolan‐4‐ylmethoxy)‐ethyl vinyl ether, IpGEVE) was designed as the precursor of a novel type of hydrophilic poly(vinyl ether) containing glycerol pendants. It was found that the polymerization of IpGEVE proceeded in a controlled manner, and the protecting groups of isopropylidene moieties could be cleaved with trifluoroacetic acid. Living cationic polymerization of IpGEVE with an initiator bearing a methacryloyl group (VEM‐HCl) and subsequent deprotection of the pendant isopropylidene groups of the resultant precursor afforded a glycerol‐substituted hydrophilic macromonomer MA‐PGEVE. Nearly monodispersed polymer particles in the submicron size range were successfully obtained via dispersion copolymerization of MA‐PGEVE with styrene.© 2013 Society of Chemical Industry     

Self-Assembly of Pyridine-Modified Lipoic Acid Derivatives on Gold and Their Interaction with Thyroxine (T4)

Pyridyl derivatives of lipoic acid were prepared as ligands for the study of the interaction with thyroxine (T4). Thin self-assembled films of the ligands were prepared in 70% ethanol on gold and their interaction with T4 was studied by titration experiments in an aqueous buffer solution using Surface Plasmon Resonance (SPR). The thickness and refractive index of the ligand layers were calculated from SPR spectra recorded in two media, also allowing for surface coverage and the density of the layers to be estimated. Two ligands, a 4-pyridyl and a bis(2-hydroxyethyl) derivative of lipoic acid, were selected to investigate the feasibility for producing molecularly imprinted self-assembled layers on gold for T4. The methodology was to co-assemble T4 and the ligand onto the gold surface, elute the T4 from the layer under alkaline conditions, and study the rebinding of T4 to the layer. Multiple elution/rebinding cycles were conducted in different buffer solutions, and rebinding of T4 could be observed, with a moderate binding affinity that depended greatly on the solvent used. More optimal binding was observed in HBS buffer, and the affinity of the interaction could be slightly increased when the 4-pyridyl and bis(2-hydroxy-ethyl) derivatives of lipoic acid were combined in the imprinted layer.     

A bio-based adhesive composed of polyelectrolyte complexes of lignosulfonate and cationic polyelectrolytes

Abstract

Polyelectrolyte complexes composed of lignosulfonate and cationic polyelectrolytes were used as bio-based adhesives. Sodium lignosulfonate (L-SO₃Na), a wood-derived anionic polyelectrolyte, was combined with three different cationic polyelectrolytes and the adhesive strength of the resulting complexes was evaluated on various substrates. Higher adhesive strength was observed with polar substrates (stainless steel, aluminum, and wood) compared to a nonpolar substrate (polypropylene). Complexes L-SO₃Na/poly(allylamine) and L-SO₃Na/ε-poly-l-lysine exhibited higher adhesive strength than the other polyelectrolyte complexes on aluminum and a commercial polyvinyl acetate adhesive on wood. In addition, our adhesives do not require any additional chemical reagents, such as organic solvents, crosslinkers, or condensation agents. The L-SO₃Na/ε-poly-l-lysine complex is a strong and completely biodegradable adhesive. This study demonstrates the use of lignosulfonate in the development of low-toxicity, sustainable, and biodegradable adhesives with excellent adhesive strength.     

Helix formation of charged polypeptides in polyion complexes with weak and strong polyelectrolytes prepared in aqueous alcohols

Using circular dichroism, the helix contents of sodium poly(L -glutamate) (PLGNa) and poly(L -lysine) hydrobromide (PLLHBr) in their weak and strong polyelectrolyte complexes have been estimated in aqueous alcohol solutions. Helix (de)stabilization observed in the systems is compared with earlier results on the PLGNa/PLLHBr polyion complex.     

Induced-charge electrophoretic motion of ideally polarizable particles

The induced-charge electrophoretic (ICEP) motion of ideally polarizable particles is numerically studied in this paper. A complete three-dimensional multi-physics model is set up to simulate the transient ICEP motion of ideally polarizable, spherical particles in an unbounded liquid. The study shows the nonlinear induced zeta potential on the particle's surface causing a varying slipping (electroosmotic flow) velocity along the particle's surface, and hence producing microvortexes in the liquid. ICEP particle-particle interactions are also studied. The simulations show that a low pressure zone between the two polarizable conducting particles will be induced if the external electric field is applied parallel along the imaginary line connecting the two particles, resulting in an attracting effect between the two particles. Oppositely, a high pressure zone is induced between the two particles if the applied field is perpendicular to the imaginary line connecting the two particles, giving a repelling effect. The ICEP attracting or repelling effects depend on the particles’ separation distance, the electric field strength and the particle size.     

交联聚合物颗粒深部调驱技术的应用

为提高交联聚合物颗粒在高含水、非均质性严重的油藏中深部调驱的应用效果,通过粒径分析、岩心驱替等实验对交联聚合物颗粒分散体系的调驱适应性进行了研究,得到了孤岛污水配制的交联聚合物分散体系在60℃条件下溶涨10 d后粒径中值增大了34倍;其单管岩心封堵率大于92%,双管岩心驱油实验提高采收率大于11%,在由6 口水井和17口油井组成的现场试验中平均注入油压上升了1.2 MPa,对应中心油井见效高峰期含水率下降了5.6%,平均增产原油5 t/d.表明了交联聚合物颗粒分散体系完全能够满足孤岛高渗透油藏深部调驱的要求,交联聚合物颗粒深部调驱技术是改善注水剖面和降低油井含水率的有效方式.     

Complexation behavior of proteins with polyelectrolytes and random acrylic polyampholytes using turbidimetric titration

The complexation behavior of proteins with dilute solutions of a polyelectrolyte (polyacrylic acid) and a random acrylic polyampholyte composed of acrylic acid, dimethylaminoethyl methacrylate and methyl methacrylate was experimentally investigated using turbidimetric titration. The random polyampholyte had a number-average molecular weight of 70,000 and a polydispersity index of only 1·3. Polyampholyte–polyampholyte interaction (self-aggregation) and polyampholyte–protein complexation behavior was studied as a function of pH (3–9) and polymer dosage (50–400, 5000 mg polymer per g protein). Large increases in turbidity (>500%) were observed for protein–polyampholyte mixtures (compared with polyampholyte alone). However, protein analysis of the supernatant and precipitate after centrifugation revealed that only about 10% of the protein precipitated with the random polyampholyte while 90% of the protein remained in the equilibrium liquid. This implies that a very small degree of protein–polymer interaction can lead to unusually large increases in turbidity. Experiments with a single polyelectrolyte (polyacrylic acid) and oppositely-charged protein showed the opposite trend with 90% precipitation of protein. Hence, great care needs to be taken in interpretation of turbidimetric titration data.     

Characterization of synthetic and activated sludge and conditioning with cationic polyelectrolytes

This study investigates the effect of cationic polyelectrolytes on the final properties of synthetic and activated sludge. Synthetic sludge was prepared according to established procedures. Activated sludge was produced in a labscale, continuous-flow reactor which was fed with live activated sludge from a waste-water treatment plant. Capillary suction time (CST) was used to evaluate the sludge dewatering behaviour. The results from experiments indicated that the cationic polyelectrolytes had a critical effect on sludge dewatering, and made an improvement in the final properties of sludge. The two types of sludge have very similar dewatering characteristics after cationic polymer conditioning. The development of synthetic sludge is suggested also to be a possible surrogate for studying the final properties of activated sludge.     

Characterization of crosslinked,macroporous, monosized polymer particles

Macroporous, monosized poly(meta‐divinylbenzene) and poly(para‐divinylbenzene) beads have been prepared by the two‐step activated swelling method with toluene or 2‐ethylhexanoic acid as pore‐forming agents. The type of divinylbenzene isomer as well as the type of porogen has a large effect on both physical and chemical properties of the monodisperse beads. Large pores are obtained with 2‐ethylhexanoic acid as porogen while beads prepared in the presence of toluene consist of only small pores and exhibit a shrinking behavior upon drying. The beads have considerable amounts of residual vinyl groups at the end of polymerization, as determined by bromination and Fourier transform IR analysis. The morphology and texture of the particles have been investigated by scanning electron microscopy and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 152–169, 2000     

Research progress on the preparation and application of monodisperse cationic polymer latex particles

This review is focused on the features, preparation and applications of uniform cationic polymer latex particles, as well as on the formation mechanism of uniform latex particles. Substantial progress in the size and shape control of polymer latex particles has been made using several methods such as dispersion polymerization, conventional emulsion polymerization, surfactant‐free emulsion polymerization and seeded emulsion polymerization. Uniform cationic polymer latex particles have wide applications such as drug carriers, diagnostics, templates and additives. However, two major problems are the inhomogeneous size and low surface charge density, which limit further functionalization and the application of cationic polymer latex particles. Finally, the future trends and perspectives are described. Copyright © 2012 Society of Chemical Industry