Charged copolymers at an interface : a model

Bringuier, E.

doi:10.1051/jphyslet:01984004503010700

Cited by 6 publications

(5 citation statements)

References 7 publications

(10 reference statements)

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“…The best fit gives β = 1 ± 0.1. For this exponent value, the prefactor is equal to A = (9 ± 0.5) × 10 -19 N m. This agrees well with Bringuier's predictions for quenched polyelectrolyte brushes . Indeed, for quenched systems in a salt-free solution, he showed that the surface pressure is proportional to the surface concentration of the counterions ( kT α N )/σ, where k is the Boltzmann constant, T is the temperature, α is the charge fraction, N is the chains degree of polymerization, and σ is the area per chain.…”

Section: Resultssupporting

confidence: 85%

Langmuir Isotherms of Quenched and Annealed Polyelectrolyte Brushes

2000

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We report here Langmuir isotherms of diblock copolymers containing a short neutral hydrophobic sequence (polystyrene) and a long water-soluble polyelectrolyte sequence (polyvinyl-2-pyridine). This study focuses on the polyelectrolyte sequence, which is a weak polyelectrolyte when unmodified and strong polyelectrolyte when quaternized. In pure water, the surface pressure of the quenched brush is proportional to the osmotic pressure of the counterions. In water at pH 2, the annealed brush isotherms are those of a polyelectrolyte brush in the strong screening limit. In water at pH 3, a plateau appears in the annealed layer isotherms, revealing a transition from a state where the polyelectrolyte sequence is adsorbed at the interface to a strong polyelectrolyte brush state. It is not clear whether this transition is a first-order transition or a continuous compression-induced solubility of the PVP chains.

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Section: Resultssupporting

confidence: 85%

Langmuir Isotherms of Quenched and Annealed Polyelectrolyte Brushes

2000

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“…The subtleties arising in this system, such as the nature of electrostatic effects of prone vs edge-on VP/R+ rings and backbone reorientation, require more complex modeling conditions than are inherent in previous approaches. [20][21] For the methylated material, as shown in Figure 8, subphase 0.1 N KI greatly reduces the values of Aon (22 nm2/molecule with KI vs 130 nm2/molecule for pure H20) and expands the condensed phase. Both changes are consistent with this material existing in a jellyfish state.…”

Section: Resultsmentioning

confidence: 99%

Interfacial behavior of block polyelectrolytes. 6. Properties of surface micelles as a function of R and X in P(S260-b-VP240/RX)

Zhu¹,

Eisenberg²,

Lennox³

1992

Macromolecules

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The interfacial properties of AB diblock polyelectrolytes PfS;&r£>-VP2.jo/RX), where PS = polystyrene, PVP = poly(4-vinylpyridinium), R = Ci to C]8, and X = I and Br, have been studied in detail at the air-water interface using the Langmuir film balance technique. Previous studies12 have been extended to explore the scope of the surface micellization phenomenon by varying the length of the pyridinium alkylating agent (R), studying the temperature dependence of surface pressure vs mean molecular area (i.e., ir-A), and controlling the speciation and concentration of the counterion (Z_) in the aqueous subphase. Surface micelle formation is a general phenomenon for all the materials measured, as shown using transmission electron microscopy (TEM) of the corresponding Langmuir-Blodgett (LB) films. It is shown that both the counterion and the hydrophobicity of R affect the relative balance between a surface micelle whose polyelectrolyte chains are surface-adsorbed (starfish morphology) and a surface micelle whose polyelectrolyte chains are subphasesolubilized (jellyfish morphology). Plateaus observed in ir-A curves for diblocks with moderate to strong hydrophobic R groups are associated with a compression-induced solubilization of the alkylated polyelectrolyte chains. The balance between surface-adsorbed and solubilized PVP/R+ chains can be readily altered by changing the counterion from CT to Br" to I" or by changing the concentration of the counterion. The size, aggregation number, and conformation of the surface micelles derived from P(S26o-h-VP24o/RX) diblocks are shown to be readily tunable by a judicious choice of R, X, and the experimental conditions.

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“…Bringuier showed that the surface pressure of such brushes is proportional to the osmotic pressure of the counterions π ci (h 0 ). 35 Furthermore, in the osmotic regime, upon strong normal compression, the brush compression energy has been found to be equal simply to the osmotic pressure π ci (h) of the counterions (see eq 2). 11 Zhulina et al developed a self-consistent-field theory (SCF) for the osmotic brush.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…The surface pressure of a salted brush is given by 35,36 3. Annealed Polyelectrolyte Brushes in the Osmotic Regime.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Annealed Polyelectrolyte Brushes under Normal and Lateral Compressions

2000

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We report here compression force measurements of diblock copolymers containing a short neutral hydrophobic sequence (polystyrene) and a long water-soluble weak polyelectrolyte sequence (poly-(2-vinylpyridine)). This study focuses on the polyelectrolyte sequence and has been restricted to the case where the subphase is at pH 2. The lateral compressions were done using a Langmuir trough whereas the normal compressions were carried out with an atomic force microscope with a spherical particle attached to the tip. The thickness of the brush is considered as a function of the grafting density and is determined from the AFM force curves without reference to any theoretical model. At high grafting densities an "anomalous" behavior is observed, where the thickness of the brush decreases with increasing the grafting density. This is attributed to the annealed character of the polyelectrolyte.

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Charged copolymers at an interface : a model

Cited by 6 publications

References 7 publications

Langmuir Isotherms of Quenched and Annealed Polyelectrolyte Brushes

Langmuir Isotherms of Quenched and Annealed Polyelectrolyte Brushes

Interfacial behavior of block polyelectrolytes. 6. Properties of surface micelles as a function of R and X in P(S260-b-VP240/RX)

Annealed Polyelectrolyte Brushes under Normal and Lateral Compressions

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