The osmotic coefficient of spherical polyelectrolyte brushes in aqueous salt-free solution

Das, B. K.; Guo, Xiaoai; Ballauff, Matthias

doi:10.1007/3-540-47822-1_7

Cited by 49 publications

(25 citation statements)

References 23 publications

(67 reference statements)

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“…This is effectively avoided by the brush due to a territorial binding of counterions, which results in a neutralization of more than 90% of its charges. 4 However, the nature of the polyelectrolyte turns the shell into a responsive compartment acting on salinity and presence of specifically interacting cations and solvent quality. These properties make SPBs highly interesting objects.…”

Section: ■ Introductionmentioning

confidence: 99%

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations

Ezhova

Huber

2016

Macromolecules

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Unlike Na + cations, which interact with fully neutralized poly(acrylic acid) as purely electrostatic entities, cations like Ag + , Mg 2+ , and Ca 2+ exhibit specific interactions with the COO − residues of anionic polyacrylates. The present work analyzes the interaction of all four cations with a layer of polyacrylate chains grafted onto spherical polystyrene core as an outer shell. First and foremost the analysis answers the question on how these specific interactions influence the nature of the shell and solution behavior of the spherical polyelectrolyte brushes. It could be unambiguously demonstrated that Ag + , Mg 2+ , and Ca 2+ cations induce a drastic shrinking of the polyacrylate shells at cation concentrations lower by 2−3 orders of magnitude compared to the transition of a fully stretched osmotic brush to a shrunken salted brush accomplished with Na + cations. Ag + induces a particularly abrupt contraction, which comes close to the annealing of such brushes achieved with a neutralization by protons. Finally, the solution behavior of the brushes in the presence of Ag + and Ca 2+ cations is compared with the respective pattern of molecularly dissolved linear polyacrylate chains in terms of phase diagrams.

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Section: ■ Introductionmentioning

confidence: 99%

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations

Ezhova

Huber

2016

Macromolecules

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“…Different kinds of nanoparticles (NPs) [ 17 , 18 ], such as liposomes [ 19 , 20 ], hydrogels [ 21 ], silica [ 22 , 23 ], and calcium salt [ 4 ], can be used as the templates to obtain the multilayer structures. Spherical polyelectrolyte brushes (SPBs) [ 24 , 25 , 26 , 27 , 28 , 29 ], in which polyelectrolyte chains are attached onto the surface of spherical cores covalently by one end, were also reported as one of the ideal templates of polyelectrolyte multilayer nanoparticles [ 16 ]. Compared with other conventional templates for multilayer structures, SPBs have a unique brush structure to enable a larger loading rate of the functional molecules or nanoparticles, and the brush layers are very sensitive to the environmental factors, such as pH, ionic strength or temperature, which makes it easy to control the exchange of substances inside and outside the multilayer system, providing an immense potential in the applications of controlled drug release, high-efficiency nano-reactors, and high-selectivity biosensors.…”

Section: Introductionmentioning

confidence: 99%

Modification of Spherical Polyelectrolyte Brushes by Layer-by-Layer Self-Assembly as Observed by Small Angle X-ray Scattering

Tian

Han

et al. 2016

Polymers

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Abstract:Multilayer modified spherical polyelectrolyte brushes were prepared through alternate deposition of positively charged poly(allylamine hydrochloride) (PAH) and negatively charged poly-L-aspartic acid (PAsp) onto negatively charged spherical poly(acrylic acid) (PAA) brushes (SPBs) on a poly(styrene) core. The charge reversal determined by the zeta potential indicated the success of layer-by-layer (LBL) deposition. The change of the structure during the construction of multilayer modified SPBs was observed by small-angle X-ray scattering (SAXS). SAXS results indicated that some PAH chains were able to penetrate into the PAA brush for the PAA-PAH double-layer modified SPBs whereas part of the PAH moved towards the outer layer when the PAsp layer was loaded to form a PAA-PAH-PAsp triple-layer system. The multilayer modified SPBs were stable upon changing the pH (5 to 9) and ionic strength (1 to 100 mM). The triple-layer modified SPBs were more tolerated to high pH (even at 11) compared to the double-layer ones. SAXS is proved to be a powerful tool for studying the inner structure of multilayer modified SPBs, which can establish guidelines for the a range of potential applications of multilayer modified SPBs.

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“…As an application of the method for monovalent counterions, we calculate the osmotic coefficient which is defined as the fraction between the pressure and ideal pressure given by φ osm = ρ bulk /ρ id , where ρ bulk is the counterion bulk concentration and ρ id = N c /V , where V is the volume accessible to the N c counterions 68 . In Fig.…”

Section: Resultsmentioning

confidence: 99%

Effect of dielectric discontinuity on a spherical polyelectrolyte brush

Tergolina

Santos

2017

The Journal of Chemical Physics

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In this paper we perform molecular dynamics simulations of a spherical polyelectrolyte brush and counterions in a salt-free medium. The dielectric discontinuity on the grafted nanoparticle surface is taken into account by the method of image charges. Properties of the polyelectrolyte brush are obtained for different parameters, including valency of the counterions, radius of the nanoparticle, and the brush total charge. The monovalent counterions density profiles are obtained and compared with a simple mean-field theoretical approach. The theory allows us to obtain osmotic properties of the system.

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The osmotic coefficient of spherical polyelectrolyte brushes in aqueous salt-free solution

Cited by 49 publications

References 23 publications

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations

Modification of Spherical Polyelectrolyte Brushes by Layer-by-Layer Self-Assembly as Observed by Small Angle X-ray Scattering

Effect of dielectric discontinuity on a spherical polyelectrolyte brush

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The osmotic coefficient of spherical polyelectrolyte brushes in aqueous salt-free solution

Cited by 49 publications

References 23 publications

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag+, Mg2+, and Ca2+ Cations

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag+, Mg2+, and Ca2+ Cations

Modification of Spherical Polyelectrolyte Brushes by Layer-by-Layer Self-Assembly as Observed by Small Angle X-ray Scattering

Effect of dielectric discontinuity on a spherical polyelectrolyte brush

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Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations

Contraction and Coagulation of Spherical Polyelectrolyte Brushes in the Presence of Ag⁺, Mg²⁺, and Ca²⁺ Cations