scholarly journals Effect of Charge Regulation and Conformational Equilibria in the Stretching Properties of Weak Polyelectrolytes

2019 ◽  
Vol 52 (21) ◽  
pp. 8017-8031 ◽  
Author(s):  
Pablo M. Blanco ◽  
Sergio Madurga ◽  
Francesc Mas ◽  
Josep L. Garcés
Keyword(s):  
Charge Regulation ◽  
Conformational Equilibria ◽  
Weak Polyelectrolytes

scholarly journals Coupling of Charge Regulation and Conformational Equilibria in Linear Weak Polyelectrolytes: Treatment of Long Range Interactions via Effective Short-Ranged and pH-Dependent Interaction Parameters

2018 ◽  
Author(s):  
Pablo M. Blanco ◽  
Sergio Madurga ◽  
Francesc Mas ◽  
Josep L. Garcés
Keyword(s):  
Long Range ◽  
Ph Dependence ◽  
Effective Interaction ◽  
Interaction Parameters ◽  
Computational Time ◽  
Charge Regulation ◽  
Wide Range ◽  
Conformational Equilibria ◽  
Ph Dependent ◽  
Weak Polyelectrolytes

The classical Rotational Isomeric State (RIS) model, originally proposed by Flory, has been used to rationalize a wide range of physicochemical properties of neutral polymers. However, many weak polyelectrolytes of interest are able to regulate their charge depending on the conformational state of the bonds. Recently, it has been shown that the RIS model can be coupled with the Site Binding (SB) model, for which the ionizable sites can adopt two states: protonated or deprotonated. The resulting combined scheme, the SBRIS model, allows to analyse ionization and conformational equilibria on the same foot. In the present work this approach is extended to include pH-dependent electrostatic Long Range (LR) interactions, ubiquitous in weak polyelectrolytes at moderate and low ionic strengths. With this aim the original LR interactions are taken into account by defining effective Short Range (SR) and pH-dependent parameters, such as effective microscopic protonation constants and rotational bond energies. The new parameters are systematically calculated using variational methods. The machinery of statistical mechanics for SR interactions, including the powerful and fast transfer matrix methods, can then be applied. The resulting technique, to which we will refer as Local Effective Interaction Parameters (LEIP) method, is illustrated with a minimal model of a flexible linear polyelectrolyte containing only one type of rotating bonds. LEIP reproduces very well the pH dependence of the degree of protonation and bond probabilities obtained by semi-grand canonical Monte Carlo simulations, where LR interactions are taken explicitly into account. The reduction in the computational time in several orders of magnitude suggests that the LEIP technique could be useful in a range of areas involving linear weak polyelectrolytes, allowing direct fitting of the relevant physical parameters to the experimental quantities.

Thermodynamic non-ideality in charge regulation of weak polyelectrolytes

Soft Matter ◽  
2021 ◽  
Author(s):  
Alejandro Gallegos ◽  
Gary Min Chiang Ong ◽  
Jianzhong Wu
Keyword(s):  
Ionization Energy ◽  
Binding Model ◽  
Charge Regulation ◽  
Weak Polyelectrolytes ◽  
Site Binding

Polymer ionization differs from that for monomeric counterparts due to intramolecular correlations. Such effects are conventionally described in terms of the site-binding model that accounts for the ionization energy and...

Charge Regulation of Interacting Weak Polyelectrolytes

2004 ◽  
Vol 108 (15) ◽  
pp. 4840-4849 ◽  
Author(s):  
Yoram Burak ◽  
Roland R. Netz
Keyword(s):  
Charge Regulation ◽  
Weak Polyelectrolytes

scholarly journals Coupling of Charge Regulation and Conformational Equilibria in Linear Weak Polyelectrolytes: Treatment of Long-Range Interactions via Effective Short-Ranged and pH-Dependent Interaction Parameters

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 811 ◽  
Author(s):  
Pablo Blanco ◽  
Sergio Madurga ◽  
Francesc Mas ◽  
Josep Garcés
Keyword(s):  
Long Range ◽  
Ph Dependence ◽  
Effective Interaction ◽  
Interaction Parameters ◽  
Computational Time ◽  
Physical Parameters ◽  
Wide Range ◽  
Conformational Equilibria ◽  
Ph Dependent ◽  
Weak Polyelectrolytes

The classical Rotational Isomeric State (RIS) model, originally proposed by Flory, has been used to rationalize a wide range of physicochemical properties of neutral polymers. However, many weak polyelectrolytes of interest are able to regulate their charge depending on the conformational state of the bonds. Recently, it has been shown that the RIS model can be coupled with the Site Binding (SB) model, for which the ionizable sites can adopt two states: protonated or deprotonated. The resulting combined scheme, the SBRIS model, allows for analyzing ionization and conformational equilibria on the same foot. In the present work, this approach is extended to include pH-dependent electrostatic Long-Range (LR) interactions, ubiquitous in weak polyelectrolytes at moderate and low ionic strengths. With this aim, the original LR interactions are taken into account by defining effective Short-Range (SR) and pH-dependent parameters, such as effective microscopic protonation constants and rotational bond energies. The new parameters are systematically calculated using variational methods. The machinery of statistical mechanics for SR interactions, including the powerful and fast transfer matrix methods, can then be applied. The resulting technique, which we will refer to as the Local Effective Interaction Parameters (LEIP) method, is illustrated with a minimal model of a flexible linear polyelectrolyte containing only one type of rotating bond. LEIP reproduces very well the pH dependence of the degree of protonation and bond probabilities obtained by semi-grand canonical Monte Carlo simulations, where LR interactions are explicitly taken into account. The reduction in the computational time in several orders of magnitude suggests that the LEIP technique could be useful in a range of areas involving linear weak polyelectrolytes, allowing direct fitting of the relevant physical parameters to the experimental quantities.

Grand-Reaction Method for Simulations of Ionization Equilibria and Ion Partitioning in a Broad Range of pH and Ionic Strength

2019 ◽  
Author(s):  
Jonas Landsgesell ◽  
Oleg Rud ◽  
Pascal Hebbeker ◽  
Raju Lunkad ◽  
Peter Košovan ◽  
...  
Keyword(s):  
Mean Field ◽  
Coarse Grained ◽  
Reactive System ◽  
Acid Base ◽  
Buffer Solution ◽  
Reaction Method ◽  
Ionization Equilibria ◽  
Coarse Grained Simulations ◽  
Ph Range ◽  
Weak Polyelectrolytes

We introduce the grand-reaction method for coarse-grained simulations of acid-base equilibria in a system coupled to a reservoir at a given pH and concentration of added salt. It can be viewed as an extension of the constant-pH method and the reaction ensemble, combining explicit simulations of reactions within the system, and grand-canonical exchange of particles with the reservoir. Unlike the previously introduced methods, the grand-reaction method is applicable to acid-base equilibria in the whole pH range because it avoids known artifacts. However, the method is more general, and can be used for simulations of any reactive system coupled to a reservoir of a known composition. To demonstrate the advantages of the grand-reaction method, we simulated a model system: A solution of weak polyelectrolytes in equilibrium with a buffer solution. By carefully accounting for the exchange of all constituents, the method ensures that all chemical potentials are equal in the system and in the multi-component reservoir. Thus, the grand-reaction method is able to predict non-monotonic swelling of weak polyelectrolytes as a function of pH, that has been known from mean-field predictions and from experiments but has never been observed in coarse-grained simulations. Finally, we outline possible extensions and further generalizations of the method, and provide a set of guidelines to enable safe usage of the method by a broad community of users.<br><br>

scholarly journals Charge Regulation at a Nanoporous Two-Dimensional Interface

ACS Omega ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 2487-2493
Author(s):  
Mandakranta Ghosh ◽  
Moritz A. Junker ◽  
Robert T. M. van Lent ◽  
Lukas Madauß ◽  
Marika Schleberger ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Charge Regulation
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