title: Local pH and effective pKAof weak polyelectrolytes - insights from computer simulations.
abstract: In this work we study the titration behavior of weak polyelectrolytes by computer simulations. We analyze the local pH near the chains at various conditions and provide molecular-level insight which complements the recent experimental determination of this quantity. Next, we analyze the non-ideal titration behaviour of weak polyelectrolytes in solution, calculate the effective ionization constant and compare the simulation results with theoretical predictions. In contrast with the universal behaviour with respect to chain length, we find non-universality and deviations from theory with respect to polymer concentration and permittivity of the solvent. The latter we explain in terms of counterion condensation and ion correlation effects, which lead to reversal of the non-ideal titration behaviour at very low permittivities. We discuss the impact of these findings on the interpretation of experimental results.
authors.affiliation: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00 Praha 2, Czech Republic. peter.kosovan@natur.cuni.cz.
authors.forename: Lucie
authors.initials: L
authors.lastname: Nová
authors.affiliation: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00 Praha 2, Czech Republic. peter.kosovan@natur.cuni.cz.
authors.forename: Filip
authors.initials: F
authors.lastname: Uhlík
authors.affiliation: Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, 128 00 Praha 2, Czech Republic. peter.kosovan@natur.cuni.cz.
authors.forename: Peter
authors.identifier: http://orcid.org/0000-0002-6708-3344
authors.initials: P
authors.lastname: Košovan