Adsorption Of Cationic Polymer Research Articles

Single-particle electrophoresis for studying the adsorption of cationic polymers onto anionic particles.

Understanding the adsorption of polymers onto particles is crucial for many technological and biomedical applications. Even though polymer adsorption on particles is a dynamic process, most experimental techniques can only study the adsorption indirectly, in equilibrium and on the ensemble level. New analysis methods are required to overcome these limitations. We investigated the use of single-particle electrophoresis to study the adsorption kinetics of cationic polymers onto anionic particles and compared the resulting data to a theoretical model. In this approach, the electrophoretic mobility of single polystyrene (PS) particles, exposed to different concentrations of poly(2-guanidinoethyl methacrylate), was measured as a function of time. The polymer adsorption leads to an electrophoretic mobility change of the PS particle over time, from the initial negative value to a positive value at equilibrium. By fitting the kinetics data to the Langmuir model, the adsorption rate, desorption rate and equilibrium constant were determined. Finally, the adsorption kinetics of several other polymers was investigated. This showed that the presented technique enables direct analysis and comparison of the kinetics of polymer adsorption on the single-particlelevel.

Selective Water Shutoff Mechanism of Double-Crosslinked Gel-Type Selective Plugging Agent (Org)

In this paper, the selective plugging capacity of ORG plugging agent under different temperatures, different permeabilities and the same injection pressure was studied by using a self-made selective plugging simulation device. With the increase of core permeability, the water plugging rate and oil plugging rate increased, while the water plugging rate and oil plugging rate were low due to the low permeability core, but all showed good selective water plugging capacity. And the theory of molecular action of cationic polymer adsorption on rock surface was studied in the ORG plugging agent. The plugging mechanism of ORG plugging agent in the rock pore was studied.

Understanding Cationic Polymer Adsorption on Mineral Surfaces: Kaolinite in Cement Aggregates

We present a joint experimental and theoretical investigation into the adsorption of polycationic quaternary ammonium polymers on the clay mineral kaolinite. Within the cement and concrete manufacturing industries such polymers are used to improve the final product by inerting the adsorption capacity of the clay minerals for more expensive additives. The adsorption of the presently used polymer (FL22) was compared with both a similar variant, but without a hydroxyl group (Fl22mod) and uncharged polyvinyl alcohol (PVA). Experimental results show that adsorption of FL22 is higher than that of FL22mod at both pH 6 and at pH > 10 and that the adsorption of PVA is the highest. Theoretical density functional theory (DFT) results and simplified models consisting of the basal surfaces of kaolinite, with monomers of FL22, FL22mod and PVA gave monomer coverage per unit surface area of kaolinite, a comparison of the configurations of the relaxed models, formation energies and Mulliken charges. These results show that the polycationic polymers interact with the basal surfaces of kaolinite electrostatically, explaining the high affinity of these polymers for kaolinite surfaces in the experimental results. The hydroxyl groups of FL22 and PVA form hydrogen bonds with the basal surfaces of kaolinite in conditions of pH 6. The joint experimental and theoretical results suggest that, due to the presence of the hydroxyl group, the conformation of FL22 changes under pH, where at neutral pH it lies relatively flat to the kaolinite surfaces, but at higher pH, conformational changes of the polymer occur, thereby increasing the adsorbed quantity of FL22.

Effect of structure of cationic comb copolymers on their adsorption and stabilization of titania nanoparticles.

Cationic linear polymer poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride) p(METAC), neutral brush polymer poly(poly(ethylene glycol) methyl ether methacrylate) p(PEO22MEMA), and cationic comb copolymers p(METAC-PEO(x)MEMA) were used for the stabilization of titania dispersions under neutral and alkaline conditions. Random comb copolymers p(METAC-PEO(x)MEMA) differing in charge density and length of PEO side chains were synthesized by RAFT. The adsorption of cationic polymers on titania nanoparticles was evaluated by thermogravimetric analysis; changes in surface potential, by measuring the zeta potential; and the stability of the treated TiO2 dispersions, by laser diffraction and DLS. Cationic linear and comb copolymers containing relatively short PEO side chains promoted the inversion of nanoparticle surface potential from strongly negative (-60 mV) to moderately positive (10-35 mV). Cationic comb copolymers containing longer PEO side chains increased the zeta potential of the treated nanoparticles but did not invert it to positive. Aqueous dispersions of titania nanoparticles stabilized by cationic comb copolymers under alkaline conditions (pH 10) were dispersed by high-energy planetary ball milling up to a primary particle size of 20 nm and were stable for at least 2 days.

The investigation of a new moderate water shutoff agent: Cationic polymer and anionic polymer

ABSTRACTCationic polymers and anionic polymers were selected as a moderate water shutoff agent for water production control. Due to the adsorption of polymers on the sand surface, the adsorption capacity under static condition, in porous media, and adsorption morphology on mica were investigated through starch–cadmium iodide method, core flow test, and atomic force microscopy measurement. The adsorption quantity on the sand surface increased with the high polymer concentrations and long adsorption time. With the increase of temperature and shearing time, the adsorption capacity slightly decreased. In addition, the adsorption capacity under water wettability condition was significantly larger than that under oil wettability condition. Alternate injection of cationic polymer and anionic polymer caused larger adsorption capacity in the core test. An adsorption multilayer was formed through alternate adsorption of cationic polymer and anionic polymer confirmed by atomic force microscopy. The visual simulation experiment was also conducted to illustrate adsorption and enhanced oil recovery mechanism. The polymers preferentially entered the high permeability zone and adsorbed on the sand surface, thus enhanced oil recovery. Furthermore, alternate injection of cationic and anionic polymers as a moderate water shutoff agent was successfully applied for water production control in oilfield test. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39462.

Adsorption of cationic polymers on the surfaces of anionic glass microspheres

The adsorption of cationic copolymers prepared by the quaternization of poly(4-vinylpyridine) with bromoacetic acid and/or ethyl bromide on the surface of anionic glass microspheres and the stability of the as-prepared complexes against dissociation in water-salt solutions are studied. Experiments are performed with the use of two types of copolymers: copolymers carrying cationic and hydrophobic units and copolymers carrying cationic and zwitterionic (electroneutral) units in main chains. For hydrophobic copolymers, the limiting adsorption decreases as the molar fraction of cationic groups in the copolymer, α, increases. In the case of hydrophilic copolymers, the dependence of limiting adsorption on α has a bellshaped pattern with a maximum at α = 0.15 and a horizontal segment at α > 0.4. Hydrophobic copolymers feature irreversible binding with microspheres at α > 0.24; hydrophilic copolymers, at α ≥ 0.15. The obtained data may be used for creation of biocidal polymer coatings and sorption layers that reversibly desorb from the surface with a change in the salt concentration in the surrounding aqueous solution.

Cationic polymer adsorption on bilayer membrane containing anionic and cationic lipids

Microelectrophoresis, dynamic light scattering, fluorescence, and microcalorimetry are used to study the adsorption of a synthetic polycation, poly-N-ethyl-4-vinylpyridinium bromide, on the surface of three-component liposomes formed from electrically neutral phosphatidylcholine, anionic diphosphatidylglycerol (cardiolipin), and cationic dicetyldimethylammonium bromide, with the two latter being taken in equal amounts. The adsorption of the polycation on the liposomal membrane results in the generation of a positive charge, which provides the polycation-liposome complex with aggregation stability. Increasing salt concentration in the suspension causes the complex to dissociate into its components. According to the microcalorimetry data, the membranes of the initial three-component liposomes consist of two microphases, with one of them being enriched with the neutral lipid and another one, with the ionic components. The polycation adsorption does not lead to noticeable structural rearrangements in the liposomal membranes.

Formation and characteristics of cationic-polymer/bentonite complexes as adsorbents for dyes

The adsorption of cationic polymer, i.e., epicholorohydrin-dimethylamine polyamine (EPI-DMA), on bentonite particles was investigated under various conditions of bulk polymer concentration, pH, inorganic salts, and temperature. The resulting high adsorption rate and alkaline solution (pH = 7–11) effect indicated a strong electrostatic interaction between the clay particles and EPI-DMA molecules. Addition of salt can also influence the adsorption of EPI-DMA onto bentonite by affecting the clay particle sizes, the polymer zeta potential and etc. The Freundlich and Langmuir isotherm models were employed and fit the experimental data well in the low EPI-DMA concentration range 0.5–5.0 mg L − 1 . The enthalpy implied by the temperature dependence of adsorption of EPI-DMA on bentonite is 7.93 kJ mol − 1 , suggesting that neither coordination exchange nor chemical bond forces exit in this system. In addition, at high temperatures, larger amounts of EPI-DMA were adsorbed by bentonite, which indicated that increased entropy in the dissolved EPI-DMA molecules contributes to adsorption. The X-ray diffraction (XRD) analysis showed that besides the EPI-DMA molecules intercalated between the layers of bentonite, excess polymer molecules were adsorbed onto polymer loops protruding from the surface of the complex. The TGA and corresponding DSC plots demonstrated that the EPI-DMA polymer had intercalated into the clay layers and thus the EPI-DMA/bentonite was more hydrophobic than natural bentonite. With the addition of EPI-DMA polymer, the negatively charged clay particles increased to a net positive charge and the capacity for dye removal also went up with increasing polymer contents in EPI-DMA/bentonite complexes.

Comparison of cationic demand between olive wood organosolv pulp and eucaliptus kraft pulp

The present work has evaluated the variation of cationic demand in function of refining degree for two unbleached cellulosic pulps: a eucalyptus pulp proceeding from a kraft process and an olive wood pulp proceeding from an organosolv process. In the organosolv process, a mixture of ethanolamine, sodium hydroxide and water has been used. For each kind of pulp, fines percentage, weighted medium length of fines, specific surface, carboxyl group's content, water retention value and cationic demand in function of refining degree have been obtained. Cationic demand has been evaluated by means of colloidal titration. Results obtained suggest the use of olive wood organosolv pulp for industrial purposes need to be enhanced. To achieve the same refining degree than eucalyptus pulp, a lot of refining time was needed. It has been observed also that in eucalyptus pulp, polymer fixation by ionic exchange is higher than adsorption. On the other hand in olive pulp, adsorption of cationic polymers prevailed over electrostatic interactions. The great content of fines in olive pulp and its higher values of carboxyl group's density could explain this behaviour.

PH triggered release of protective poly(ethylene glycol)-b-polycation copolymers from liposomes

Triggered release of adsorbed polymers from liposomes enables protection against immune recognition during circulation and subsequent intracellular delivery of DNA. Polycationic blocks, poly[2-(dimethylamino) ethyl methacrylate] (DMAEMA) (0.8, 3.1, 4.9, or 9.8 kg/mol) or polylysine (K) (3 kg/mol), act as anchors for poly(ethylene glycol) (PEG) (2 or 5 kg/mol) protective blocks. In addition, a copolymer with 15 strictly alternating blocks of PEG (2 kg/mol) and cationic amine sites was evaluated as a protective coating. Incorporation of 1,2-dioleoyl-3-dimethylammonium-propane, a titratable lipid with a pKa of ∼6.7, allows the liposome's net charge to increase as the pH shifts from 7.4 in the bloodstream to 5.5 in the endosome. The increased net liposome cationicity results in decreased cationic polymer adsorption. The EMPEG113–DMAEMA31 and EMPEG113–DMAEMA62 association constants decrease from 3.1 and 6.2 (mg/m 2)/(mg/ml) at pH 7.4 to 1.7 and 3.2 (mg/m 2)/(mg/ml) at pH 5.5, respectively. However, EMPEG45–DMAEMA5, EMPEG45–DMAEMA20, and EMPEG45–N–DP15 did not show a strong response to changes in pH. Cationic polymer adsorption exceeds calculated values for liposome neutralization, resulting in adsorption profiles in the brush regime.

New insights into the fundamental nature of lignocellulosic fiber surface charge

The surface and total charge density of industrially manufactured hardwood and softwood grade kraft lignocellulosic fibers can mainly be attributed to carboxylic acid functionalities as determined from topochemical adsorption of a cationic polymer (methyl glycol chitosan) and the use of conductometric titration. These charge density measurement methods have led to a powerful and accurate photometric method for the quantitative analysis of surface charge. The method is based on directly monitoring the iodide ion, the counterion of the chitosan polymer, which is released upon electroneutralization between a chitosan cationic site and an anionic site at the fiber surface, thereby directly providing the concentration of surface charge. The stoichiometry for the chitosan adsorption onto the fiber surfaces is unity despite pulp types and adsorption quantity of cationic polymer. Given the high charge density of the chitosan molecule and the determined physical charge density limitations for its distribution onto the surface of pulps, a new and heretofore unused concept referred to as the subsurface was posited to adequately describe the surface charge determination after the adsorption of cationic polymer on the fibers. More specifically, within the subsurface of the suspended fibers in solution, carboxylates (COO −) were neutralized by the cationic sites of chitosan. The COO − sites in the subsurface can electrically attract positive sites of the cationic polymer, resulting in the complete release of counterions. To account for the charge density measurements, the charge measurement of the fibers includes not only nominal topochemical surface charges but also charges below this surface (subsurface).

The effect of short-chain cationic polymers on the deposition of wood resin emulsion droplets on silica surfaces

The objective of this work was to understand the mechanisms involved in the deposition of dispersed wood resin on solid surfaces. A hydrophilic silica surface, and a silica surface coated with adsorbed cationic polymer was exposed to an aqueous dispersion of wood resin. Deposition of wood resin as well as adsorption of cationic polymer were monitored by reflectometry in stagnation point flow. The deposition efficiency as well as the final deposited amount at pH 4.5 and 6.5 were measured as a function of NaCl and CaCl 2 concentration. Droplets _of wood resin do not deposit on hydrophilic silica surface even from solutions of high ionic strength. If the silica surface is covered with a layer of cationic polyelectrolyte, droplets from an electrostatically stabilised dispersion deposit on the collector surface. In this case the deposition efficiency roughly agrees with barrier-less deposition. When the ionic strength is increased to render the dispersion somewhat unstable, the rate of deposition decreases. No deposition occurs if the dispersion is rendered completely unstable by addition of electrolyte. The dependence of the final deposited amount on ionic strength and added polyelectrolyte can be understood on the basis of the electrokinetic properties of the resin droplets.

Adsorption of Cationic Polymer onto Negatively Charged Surfaces in the Presence of Anionic Surfactant

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdsorption of Cationic Polymer onto Negatively Charged Surfaces in the Presence of Anionic SurfactantVictor ShubinCite this: Langmuir 1994, 10, 4, 1093–1100Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://doi.org/10.1021/la00016a022RIGHTS & PERMISSIONSArticle Views567Altmetric-Citations88LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Impact of polycation adsorption on efficiency and electroosmotically driven transport in capillary electrophoresis

Adsorption of analytes to the walls of fused silica capillaries is common. This paper examines the quantitative impact of cationic polymer adsorption on electroosmotically driven transport, peak symmetry, and efficiency in capillary zone electrophoresis (CZE). Polycationic species were more strongly absorbed than polymers with a small number of positive charges. Recovery of proteins generally varied inversely with the isoelectric point pI). Adsorption of positively-charged species occurred preferentially at the capillary inet, generally within a few centimeters

A tensammetric study of the adsorption of cationic polymers and copolymers

The tensammograms of several sets of cationic polyacrylamide copolymers are discussed and compared. Tensammograms are not affected by molecular weight, but plots of capacitive current at a chosen potential versus charge density give regular curves. Key words: tensammetry, cationic, polyacrylamide, charge density.

The effect of the amphiprotic nature of human hair keratin on the adsorption of high charge density cationic polyelectrolytes

Adsorption of the cationic polymers poly(methacrylamidopropyltrimethyl ammonium chloride) (PMAPTAC) and poly(1,1-dimethylpiperidinium-3,5-diallylmethylene chloride) (PDMPDAMC) on human hair was studied by measurements of the amount of polymer adsorbed and by the streaming potential method. Results reflect the amphoteric nature of the keratin surface and show that the excess of anionic sites at pH values above 4 is the main driving force for the adsorption of cationic polyelectrolytes. Lowering the pH below 4 or addition of neutral salt (KCl) reduces the amount of adsorbed polymer. It was shown that the adsorption of cationic polymer in the concentration range 0.01 to 0.1 % and at neutral pH reverses the overall character of the surface from anionic to cationic. Keratin fibers modified in this manner do not exhibit amphoteric character and bear excess positive charge in the pH range 2–9.5. The value of the amount of the polymer adsorbed at saturation concentration (∼2 mg/g) as well as the lack of molecular weight effect in the range (5 · 104 − 106) on the amount of polymer adsorbed suggest that polymer chains adopt a rather extended conformation on the fiber surface. Some data concerning the formation of a complex between adsorbed cationic polymer and anionic detergents or polyelectrolytes are also presented.