Counterion distribution in a spherical charged sparse brush

Abstract

The counterion distribution within a spherical polyelectrolyte sparse brush was measured by small-angle X-ray scattering using contrast variation with different counterions by means of ion dialysis. The brush was made by self-association of charged diblock copolymers. Thanks to the contrast variation method, we were able to separate the signal due to the monomers and the signal due to the counterions. At a small length scale, it is demonstrated that the system behaves as independent charged rods whose counterion distribution follows the Poisson-Boltzmann model.

Small-angle X-ray and neutron scattering study of Nafion-SiO2 hybrid membranes prepared in different solvent media

“…Such finding relates the origin of the Nafion SANS pattern to the contrast between the polymer aggregates with a condensed layer of counterions and the solvent [21]. In this scenario, the presence of mixed amounts of protonated and deuterated water may change the distribution of condensed counterions and decreases the correlation existing between the polymer and the counterions, eventually suppressing the ionomer peak [21,25].…”

Oil-in-water microemulsions stabilized by charged diblock copolymers

“…[4][5][6][7][8] The recent possibility to obtain results on these systems by numerical simulations 9,10 is a motivation to study this system further. When considering charged copolymers, the situation is complicated by the presence of electrostatic interactions and the great number of counterions.…”

Thickness and Density Profiles of Polyelectrolyte Brushes: Dependence on Grafting Density and Salt Concentration

“…Much more recently, new theoretical approaches have appeared which rely on a more exact treatment of electrostatic interactions [9,10], often thanks to numerical simulations [11][12][13]. These recent works predict behaviors where the brush thickness varies with grafting density either because of a collapse due to virial interactions [9,14] or because of the counter-ion condensation [10], a feature recently detected in experiments [11,15]. Given the scarce number of experiments which have undertaken the study of a pure charged brush behavior, we present in this Letter an approach using Langmuir films of asymmetric charged copolymers associated to neutron reflectometry.…”