Block polyelectrolytes and colloidal stability

Turesson, Martin; Åkesson, Torbjörn; Forsman, Jan

doi:10.1016/j.jcis.2008.09.049

Cited by 9 publications

(11 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This might be a relevant way to model AFM/SFA "approach" measurements. Performing a similar theoretical restriction as the surfaces are moved apart, often leads to a considerable hysteresis, 61,71 in qualitative agreement with AFM/SFA experiments. There have been recent attempts to account for the effects of ion correlations in these systems.…”

Section: Theoretical Approachessupporting

confidence: 67%

“…As already mentioned, high-LCD polyions normally generates an "overcharged" surface, and at low salt, interactions at long range tends to be dominated by an electrostatic double-layer repulsion. 12,15,16,20,22,32,39,[60][61][62] Consequently, addition of salt will diminish the range of this repulsion.…”

Section: Addition Of Simple Saltmentioning

confidence: 99%

“…In agreement with our previous discussion, simulations have demonstrated that a triblock structure of the polyions (or a lower LCD of the chain), in which the central part contains neutral monomers, will lead to a smaller degree of overcharging. 61 Furthermore, with a neutral mid block the energetic cost of forming bridges is reduced.…”

Section: Theoretical Approachesmentioning

confidence: 99%

See 2 more Smart Citations

Surface forces in electrolytes containing polyions and oppositely charged surfaces

Forsman

2017

Current Opinion in Colloid & Interface Science

Self Cite

View full text Add to dashboard Cite

Studies of interactions between surfaces immersed in a solution containing oppositely charged polyions are reviewed. Experimental as well as theoretical progress is discussed, focusing on underlying molecular mechanisms. * To whom correspondence should be addressed 1 particle interactions, on account of the steric repulsion that results as the polymer layers are compressed when two such particles approach. However, as the solvent gets poorer, which often can be regulated by changing the temperature or adding salt, these interactions may turn attractive, often resulting in flocculation, or the formation of a gel. 7 Ungrafted and non-adsorbing polymers tend to generate depletion attractions between the particles. If these "free" (ungrafted) polymers instead adsorb at the particle surfaces, the scenario is a bit more complex. Equilibrium interactions then tend to be overall attractive, with a free energy minimum stemming from the entropic increase that results when adsorbed chains are able to bridge across to a neighbouring particle. However, the attraction is generally short-ranged, and there is often a considerable free energy barrier at larger separations. In other words, such a dispersion may in practice be apparently (kinetically) stabilized by polymer addition. This is reminiscent to the barriers provided by electrostatic repulsion for charged particles (at low salt). Non-equilibrium phenomena are relevant also to the very interactions that the polymer give rise to. We shall discuss this in more detail below, but for now we note that finite configurational relaxation times, as well as diffusion limitations, may lead to polymer-mediated interactions that differ from those at true equilibrium. If so, it should be noted that fully relaxed states by definition have a lower free energy than their non-equilibrium corre

show abstract

Section: Theoretical Approachessupporting

confidence: 67%

Section: Addition Of Simple Saltmentioning

confidence: 99%

Section: Theoretical Approachesmentioning

confidence: 99%

See 1 more Smart Citation

Surface forces in electrolytes containing polyions and oppositely charged surfaces

Forsman

2017

Current Opinion in Colloid & Interface Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, at some intermediate critical concentration value, there is a ''perfect surface neutralization'' point, whereby the long-range repulsive barrier is negligible. [12][13][14][15][16][21][22][23][24] Experimentally, this manifests itself as a specific salt concentration where the charged particle dispersion has minimal stability. The neutralization point can also be experimentally identified through a vanishing electrophoretic mobility.…”

Section: Introductionmentioning

confidence: 99%

Interactions between conducting surfaces in salt solutions

2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…One possible way to regulate the degree of overcharging, and thus the free energy barrier, is to insert a neutral midsection of the polyions. 38 …”

Section: Introductionmentioning

confidence: 99%

Overcharging and Free Energy Barriers for Equally Charged Surfaces Immersed in Salt Solutions

Stenberg

Forsman

2021

Langmuir

Self Cite

View full text Add to dashboard Cite

The stability of dispersions containing charged particles may obviously be regulated by salt. In some systems, the effective charge, as measured by the potential some small distance away from the particles, can have a sign opposite to the bare surface charge. If charge reversal takes place, there is typically a salt concentration regime within which colloidal stability increases with added salt. These experimental findings on dispersions have been corroborated by atomic force microscopy investigations, where an attraction is found at short separations. This attraction is stronger than expected from standard DLVO theory, and there has been considerable debate concerning its origin. In this work, we use simple coarse-grained models of these systems, where the bare surfaces carry a uniform charge density, and ion-specific adsorption is absent. Our hypothesis is that these experimental observations can be explained by such a simplistic pure Coulomb based model. Our approach entails grand canonical Metropolis Monte Carlo (MC) simulations as well as correlation-corrected Poisson-Boltzmann (cPB) calculations. In the former case, all ions have a common size, while the cPB utilizes a point-like model. We devote significant attention on apparent surface charge densities and interactions between large flat model surfaces immersed in either a 2:1 salt or a 3:1 salt. In contrast to most of the previous theoretical efforts in this area, we mainly focus on the weak long-ranged repulsion and its connection to an effective surface charge. We find a charge reversal and a concomitant development of a free energy barrier for both salts. The experimentally observed nonmonotonic dependence of colloidal stability on the salt concentration is reproduced using MC simulations as well as cPB calculations. A strong attraction is observed at short range for all investigated cases. We argue that in our model, all non-DLVO aspects can be traced to ion–ion correlations.

show abstract

Block polyelectrolytes and colloidal stability

Cited by 9 publications

References 26 publications

Surface forces in electrolytes containing polyions and oppositely charged surfaces

Surface forces in electrolytes containing polyions and oppositely charged surfaces

Interactions between conducting surfaces in salt solutions

Overcharging and Free Energy Barriers for Equally Charged Surfaces Immersed in Salt Solutions

Contact Info

Product

Resources

About