Electrostatic Self-Assembly of Oppositely Charged Copolymers and Surfactants:  A Light, Neutron, and X-ray Scattering Study

Berret, Jean‐François; Vigolo, Brigitte; Eng, Ronny; Hervé, Pascal; Grillo, Isabelle; Yang, Lin

doi:10.1021/ma0498722

Cited by 119 publications

(239 citation statements)

References 41 publications

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“…In aqueous solutions at neutral pH, the chains are dispersed and in the state of unimers. Light scattering performed in the dilute regime have revealed a molecular weight M W = 35 000 ± 2000 g mol -1 and an hydrodynamic diameter D H = 11 ± 1 nm [8]. The polydispersity index was determined by size exclusion chromatography at 1.6.…”

Section: Ii1 -Polymersmentioning

confidence: 99%

Reorientation kinetics of superparamagnetic nanostructured rods

Fresnais¹,

Berret²,

Frka‐Petesic³

et al. 2008

J. Phys.: Condens. Matter

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The attractive interactions between oppositely charged species (colloids, macromolecules etc) dispersed in water are strong, and the direct mixing of solutions containing such species generally yields to a precipitation, or to a phase separation. We have recently developed means to control the electrostaticallydriven attractions between nanoparticles and polymers in water, and at the same time to preserve the stability of the dispersions. We give here an account of the formation of supracolloidal aggregates obtained by co-assembly of 7 nm particles with copolymers. Nanostructured rods of length comprised between 5 and 50 μm and diameter 500 nm were investigated. By application of a magnetic field, the rods were found to reorient along with the magnetic field lines. The kinetics of reorientation was investigated using step changes of the magnetic field of amplitude /2. From the various results obtained, among which an exponential decay of the tangent of the angle made between the rod and the field, we concluded that the rods are superparamagnetic. @ :

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Section: Ii1 -Polymersmentioning

confidence: 99%

Reorientation kinetics of superparamagnetic nanostructured rods

Fresnais¹,

Berret²,

Frka‐Petesic³

et al. 2008

J. Phys.: Condens. Matter

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“…In the present paper, we have re-examined neutron scattering data that were obtained on colloidal complexes resulting from the self-assembly between charged-neutral copolymers and oppositely charged surfactants [34][35][36][37]40 . Two block copolymers/surfactant systems are highlighted, on one hand 15 poly(acrylic acid)-b-poly(acrylamide) with dodecyltrimethylammonium bromide and on the other hand poly(trimethylammonium ethylacrylate methylsulfate)-b-poly(acrylamide) with sodium dodecyl sulfate.…”

Section: -Concluding Remarksmentioning

confidence: 99%

“…In the present survey, we report on two block copolymers/surfactant systems [34][35][36][37] . The first system is the anionic-neutral copolymer poly(acrylic acid)-b-poly(acrylamide) which is studied in Poly(acrylic acid) is a weak polyelectrolyte and its ionization state depends on the pH.…”

Section: Iii1 -Materials and Characterizationmentioning

confidence: 99%

Evidence of overcharging in the complexation between oppositely charged polymers and surfactants

Berret¹

2005

The Journal of Chemical Physics

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105

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:We report on the complexation between charged-neutral block copolymers and oppositely charged surfactants studied by small-angle neutron scattering. Two block copolymers/surfactant systems are investigated, poly(acrylic acid)-b-poly(acrylamide) with dodecyltrimethylammonium bromide and poly(trimethylammonium ethylacrylate methylsulfate)-b-poly(acrylamide) with sodium dodecyl sulfate. The two systems are similar in terms of structure and molecular weight but have different electrostatic charges. The neutron scattering data have been interpreted in terms of a model that assumes the formation of mixed polymersurfactant aggregates, also called colloidal complexes. These complexes exhibit a core-shell microstructure, where the core is a dense coacervate microphase of micelles surrounded by neutral blocks. Here, we are taking advantage of the fact that the complexation results in finitesize aggregates to shed some light on the complexation mechanisms. In order to analyze quantitatively the neutron data, we develop two different approaches to derive the number of surfactant micelles per polymer in the mixed aggregates and the distributions of aggregation numbers. With these results, we show that the formation of the colloidal complex is in agreement with overcharging predictions. In both systems, the amount of polyelectrolytes needed to build the core-shell colloids always exceeds the number that would be necessary to compensate the charge of the micelles. For the two polymer-surfactant systems investigated, the overcharging ratios are 0.66 ± 0.06 and 0.38 ± 0.02. I -IntroductionThe complexation between ion-containing polymers and oppositely charged macroions is currently attracting much attention in the field of soft condensed matter 1,2 . Associations based on the electrostatic Coulomb interactions are present in many applications and for highly charged systems the elementary mechanisms such as adsorption and self-assembly are only partially understood. The complexation between oppositely charged species is found e.g. in the treatment of waste water, the formulation of personal care products, the purification of proteins or in gene and drug delivery. In biophysics, comprehensive studies have been dedicated to the cooperative condensation of DNA with multivalent counterions [3][4][5] or with cationic liposomes 1,[6][7][8][9] . In material science, electrostatic layer-by-layer deposition yielding polyelectrolyte multilayers have been achieved for encapsulation purposes and colloidal stabilization [10][11][12] .When an ion-containing polymer solution is mixed to a dispersion of oppositely charged colloids, a phase separation usually follows [13][14][15][16][17][18][19][20][21][22][23] . At the mixing, the solution becomes turbid, and after centrifugation it displays two separated phases. The bottom phase appears as a precipitate and its chemical analysis reveals that it contains most of the polymers and colloids. The supernatant is fluid and transparent, and contains the solvent and the counterions released d...

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“…In aqueous solutions at neutral pH, the chains are dispersed and in a state of unimers. Light scattering performed in the dilute regime have revealed a molecular weight MW = 35 000 g mol -1 and an hydrodynamic diameter DH = 11 nm [10,11]. Complexation schemes were realized using cerium oxide nanoparticles or surfactant micelles that were of opposite charge with respect to that of the polymers.…”

mentioning

confidence: 99%

Stability and Adsorption Properties of Electrostatic Complexes: Design of Hybrid Nanostructures for Coating Applications

Qi¹,

Chapel²,

Castaing³

et al. 2007

Langmuir

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We report the presence of a correlation between the bulk and interfacial properties of electrostatic coacervate complexes. Complexes were obtained by co-assembly between cationic-neutral diblocks and oppositely charged surfactant micelles or 7 nm cerium oxide nanoparticles. Light scattering and reflectometry measurements revealed that the hybrid nanoparticle aggregates were more stable both through dilution and rinsing (from either a polystyrene or a silica surfaces) than their surfactant counterparts. These findings were attributed to a marked difference in critical association concentration between the two systems and to the frozen state of the hybrid structures.The design of functional molecular architectures and materials has attracted much attention during the last decade. In particular, the controlled association of polymers and nanoparticles using covalent [1][2][3] and noncovalent [4][5][6] binding has appeared as a promising way to combine organic and inorganic moieties at a nanoscospic level. The development of hybrid nanostructures was also stimulated by industrial and biomedical applications, especially by applications in the realm of coating technologies. In order to modify the surface properties of materials, inorganic nanoparticles with unique physical features (such as magnetic, fluorescent, UV-absorbent, high dielectric constant or catalytic properties) are actually crucial ingredients. In association with macromolecules, these nanoparticles could be also used for coatings with improved stability and performances (wetting, antibiofouling).In 2004, Cohen Stuart and coworkers have shown that electrostatic complexes made from oppositely charged polyelectrolytes could be effectively adsorbed on hydrophilic and hydrophobic surfaces [7][8][9]. Experiments were conducted at the liquid-solid interfaces on electrostatic core-shell complexes resulting from the selfassembly of an anionic-neutral copolymer and a short cationic homopolymer. On silica and polystyrene substrates, it was found that the cores of the aggregates adsorbed on the surface whereas the shell formed a brush on the top of it. These authors also confirmed the stability of the deposited layer upon rinsing and its repellent effect with respect to proteins [7]. The approach followed in the present communication aimed to extend these measurements to two new types of electrostatic systems, namely to organic and hybrids coacervate complexes. Here, we show the existence of a correlation between the bulk and adsorption properties of surfactant/copolymer (organic) and nanoparticle/copolymer (hybrid) complexes. Using Stagnation Point Adsorption Reflectometry (SPAR), organic and hybrid complexes were found to adsorb readily on hydrophilic and hydrophobic substrates. However, upon rinsing the organic complexes were shown to disassemble and finally desorb from the solid surface, whereas the hybrids remained. These findings were interpreted in terms of a critical association concentration which is much higher for organic systems than for the hybrids.Fo...

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Electrostatic Self-Assembly of Oppositely Charged Copolymers and Surfactants: A Light, Neutron, and X-ray Scattering Study

Cited by 119 publications

References 41 publications

Reorientation kinetics of superparamagnetic nanostructured rods

Reorientation kinetics of superparamagnetic nanostructured rods

Evidence of overcharging in the complexation between oppositely charged polymers and surfactants

Stability and Adsorption Properties of Electrostatic Complexes: Design of Hybrid Nanostructures for Coating Applications

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