Polyelectrolyte complex formation at the interface of solutions

Dautzenberg, H.; Arnold, George B.; Tiersch, Brigitte; Lukanoff, B.; Eckert, Uwe

doi:10.1007/bfb0114461

Cited by 29 publications

(24 citation statements)

References 7 publications

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“…Stoichiometric 1 : 1 composition is reported for some systems 32,62,63,121,130,203,351,401) , whereas indications for nonstoichiometric compositions were reported for others 30,32,187,353,398,400,403,441) . This is not surprising, as the adsorption of the newly adsorbed polyion at the interface resulting in charge overcompensation resembles the formation of non-stoichiometric polyelectrolyte complexes in solution [442][443][444] . In particular for polymers with pHdependent ionic groups, the composition will depend on the conditions chosen, such as pH or salt content.…”

Section: The Structure Of Polymer Films Made By Esamentioning

confidence: 94%

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Bertrand

Jonas

Laschewsky³

et al. 2000

Macromol. Rapid Commun.

1,169

1,184

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A bit of historyThe key role of surfaces for many material properties as well as for many biological processes has been recognized now. Therefore, new strategies aim at the tailoring of the material's surface only -or of a thin surface layer, respectively -, while preserving the bulk properties of the underlying support. Particular emphasis has been given to the surface modification by polymers, in an attempt to extend the known versatility of polymer bulk materials to ultrathin films and coatings, and to prepare bulk-surface composite materials. The self-organization of polymers has been increasingly explored for the preparation of well-defined surfaces and interfaces in recent years, extending the use of the established methods of low molar mass compounds (for comparative reviews, see ref. 1-3)). With such techniques, polymer films are formed spontaneously on substrates, due to balanced interactions between substrate, polymer (or its precursor) and medium. Typically, very thin, often monomolecular layers are produced. Repetitive deposition steps provide a precise control over the total thickness of the coatings, in the range from a few angstroms up to the micrometer range. Moreover, the step-by-step procedures allow for a fine structuring in the third dimension. In addition to the preparation of uniform and homogeneous coatings, gratings, gradients or steps of defined height in molecular dimensions can be easily constructed.The most recent of the self-organization techniques is the alternating physisorption of oppositely charged polyelectrolytes, the so-called "layer-by-layer" method or "electrostatic self-assembly" (ESA) [3][4][5][6][7][8][9][10] . Although some early, singular studies of self-assembly by alternating adsorption of oppositely charged polyions are reported [11][12][13] , a practical method for ESA was developed Feature Article: The article presents the state-of-the-art of alternating physisorption of oppositely charged polyelectrolytes, the so-called "layer-by-layer" method or "electrostatic self-assembly" (ESA), for the preparation of thin polymer coatings. In comparison to other, more established self-organization techniques, this recent method is distinguished by its simplicity, versatility, and speed. In particular, the tendency for self-healing is unique. Emphasis is given to the role of the molecular structure of the polyelectrolytes, and to the nature of the support. Also, various parameters for the preparation of multilayer films are highlighted, which are very important due to the kinetic control of the build-up process. The structure of the resulting coatings, their quality and stability, chemical reactions in the films, and potential applications are discussed.Macromol. Rapid Commun. 21, No. 7

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Section: The Structure Of Polymer Films Made By Esamentioning

confidence: 94%

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Bertrand

Jonas

Laschewsky³

et al. 2000

Macromol. Rapid Commun.

1,169

1,184

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“…Such an interfacial complexation reaction is well-established for macroscopic contact of two solutions containing oppositely charged polyelectrolytes and may lead, for example, to symplex microcapsules or symplex membranes. [20,21] Remarkably, the large excess of one type of polyelectrolyte in the surrounding solution, compared to the minimal amount present in the hypothetical lamella, does not result in soluble, non-stoichiometric polyelectrolyte complexes. The symplex film probably accrues by diffusion of polyelectrolyte chains from both sides to the liquid±liquid surface, followed by formation of a polyelectrolyte network.…”

mentioning

confidence: 99%

Direct Access to Stable, Freestanding Polymer Membranes by Layer‐by‐Layer Assembly of Polyelectrolytes

Mallwitz

Laschewsky

2005

Advanced Materials

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The alternating, layer-by-layer assembly of oppositely charged polyelectrolytes, often referred to as electrostatic self-assembly (ESA), has been well-established in the past decade for the preparation of ultrathin polymer films with precise thicknesses of between 1 and 1000 nm. [1,2] The method is based on the formation of water-insoluble, nearly stoichiometric complexes of polycations and polyanions (so-called ªsymplexesº) at an interface. Characteristically, the preparation of ESA films involves the use of an appropriate substrate onto which the polymers are adsorbed layer by layer. Consequently, the ESA method results, first of all, in the surface modification of a given substrate. However, ultrathin polymer films are often desirable as freestanding films. [3,4] In fact, numerous examples have been reported in which the substrate was removed after film preparation in order to prepare substrate-free films, particularly in cases where colloidal supports have been used. [5,6] In these cases, hollow polyelectrolyte capsules dispersed in liquid are produced by the dissolution or decomposition of the substrate. [5,7] Following the same strategy, planar films without a supporting substrate have also been prepared in exceptional cases, either by removing the entire support or by dissolving a thin buffer coating between the primary substrate and the stable ESA film. [3,8±14] In all these examples, the preparation of freestanding, ultrathin polymer films required two steps: first, film growth on a substrate and second, the removal of the substrate. This twostep approach is not only cumbersome, but may also damage the ultrathin polymer films as a result of, for example, chemical and mechanical stresses during the removal of the substrate. In fact, nearly all examples of freestanding films have been made using charged colloidal particles, which have been used to improve the mechanical stability of the films. [3,10±13] Therefore, direct access to freestanding ESA films, which is suited for organic, flexible polyelectrolytes, appears very attractive. In this communication, we present a strategy to prepare ultrathin, freestanding ESA films directlyÐi.e., without using a substrateÐwith a thickness/width ratio of up to 1:10 000, by appropriately choosing the polyelectrolyte pair and conditions for self-assembly. We also investigate the response of the freestanding films to chemical stimuli before and after their stabilization by chemical crosslinking.In order to prepare freestanding films, we used electron microscopy (EM) grids, with typical hole sizes of 100 lm 100 lm, as supports. Although the formation of films which successfully span pores has been reported occasionally using supports with very small pores (< 50 nm), [15,16] so far, the use of supports with larger pores has resulted in coating of the pore walls.[8,9,17±19] Indeed, when we used the classical experimental conditions during the dipping cyclesÐ namely, washing between subsequent dipping steps and drying in ambient atmosphereÐall our attempts to obtain f...

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“…They have also been successfully applied as ecient binders of dispersed systems such as soils and sands to protect them from water and/or wind erosion [5]. IPECs were shown to be suitable for the construction of enzymatic systems with controllable activity and stability [9,10], for the preparation of membranes [11,12] and microcapsules [12,13], for the immobilization of microorganisms [14], for the surface modi®cation of solid materials [15,16], etc. The biocompatibility of IPECs is a unique feature that opens many possibilities for their application as coatings for medical materials used in a contact with blood and other biological liquids [17,18].…”

mentioning

confidence: 99%

Effect of a low-molecular-weight salt on colloidal dispersions of interpolyelectrolyte complexes

Pergushov

Buchhammer²,

Lunkwitz³

1999

Colloid Polym Sci

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IntroductionIt is well known that electrostatic interaction between oppositely charged macromolecules leads to the formation of interpolyelectrolyte complexes (IPECs) [1]. Such macromolecular assemblies are predominantly stabilized by a cooperative system of interpolymer salt bonds although other intermacromolecular interactions, for example, hydrogen bonding, hydrophobic interactions, charge-transfer interactions, and van der Waals forces, can also play a signi®cant role. The structure and properties of IPECs are determined by a number of factors: the characteristics of the polyelectrolyte components (e.g., nature of ionic groups, degree of polymerization, charge density, etc.) and their concentrations, the ratio between amounts of oppositely charged groups of polyelectrolytes, the conditions of the surrounding medium (e.g., ionic strength, pH, temperAbstract Colloidal dispersions of an interpolyelectrolyte complex were prepared by mixing dilute aqueous solutions of poly(dimethyldiallylammonium chloride) and the sodium salt of the alternating copolymer of maleic acid propene in amounts providing about a threefold excess of the charged groups of the cationic polyelectrolyte over those of the anionic polyelectrolyte. These dispersions were examined by means of analytical sedimentation, quasielastic light scattering, and laser Doppler microelectrophoresis. The experimental results obtained suggest that the particles of the interpolyelectrolyte complex are multicomplex aggregates bearing cationic charge. Such aggregates were assumed to consist of a hydrophobic core formed by coupled oppositely charged macromolecules and a hydrophilic shell formed by cationic macromolecules. Hydrodynamic and electrophoretic properties of these aggregates were found to be rather sensitive to variations in the ionic strength of the surrounding medium: with rising salt concentration, their sedimentation coecient and hydrodynamic size increase, these increases becoming more strongly pronounced at higher salt concentrations, whereas their electrophoretic mobility gradually decreases. The salt eects revealed suggest that the aggregation level of the particles of the interpolyelectrolyte complex rises in response to an increase in the ionic strength of the surrounding medium. This phenomenon was associated with the salt-induced decrease of the stabilizing eect of the hydrophilic shells that protect such particles from progressive aggregation.

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Polyelectrolyte complex formation at the interface of solutions

Cited by 29 publications

References 7 publications

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

Direct Access to Stable, Freestanding Polymer Membranes by Layer‐by‐Layer Assembly of Polyelectrolytes

Effect of a low-molecular-weight salt on colloidal dispersions of interpolyelectrolyte complexes

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