Manipulation of Confined Polyelectrolyte Conformations through Dielectric Mismatch

Abstract

We demonstrate that a highly charged polyelectrolyte confined in a spherical cavity undergoes reversible transformations between amorphous conformations to a four-fold symmetry morphology as a function of dielectric mismatch between the media inside and outside the cavity. Surface polarization due to dielectric mismatch exhibits an extra "confinement" effect, which are most pronounced within a certain range of the cavity radius and the electrostatic strength between the monomers and counterions and multivalent counterions. For cavities with a charged surface, surface polarization leads to an increased amount of counterions adsorbed in the outer side, further compressing the confined polyelectrolyte into a four-fold symmetry morphology. The equilibrium conformation of the chain is dependent upon several key factors including the relative permittivities of the media inside and outside the cavity, multivalent counterion concentration, cavity radius relative to the chain length, and interface charge density. Our findings offer insights into the effects of dielectric mismatch in packaging and delivery of polyelectrolytes across media with different relative permittivities. Moreover, the reversible transformation of the polyelectrolyte conformations in response to environmental permittivity allows for potential applications in biosensing and medical monitoring.

Theoretical and Computational Insight into Solvent and Specific Ion Effects for Polyelectrolytes: The Importance of Local Molecular Interactions

“…In contrast to bulk solutions, polyelectrolytes in confinement and in presence of dielectric mismatch conditions show a transitional behavior into various conformations. Here, surface polarization mechanisms as induced by a dielectric mismatch in combination with the electrostatic interactions between the monomers and multivalent counterions favor changes in the conformational behavior when compared to bulk conditions [102]. The corresponding findings reveal that specifically also the conformational properties of the polyelectrolyte are modified by distinct charge states, multivalent ions, dielectric mismatch conditions as well as the presence of confinement effects and high salt and polyelectrolyte concentrations.…”

Influence of Calcium Binding on Conformations and Motions of Anionic Polyamino Acids. Effect of Side Chain Length

“…Polymers 2020, 12, x FOR PEER REVIEW 5 of 22 We have reported results regarding simulations of PGA and PASA in water already earlier [57]. The addition of divalent CaCl2 salt in solution causes changes in chain conformations due to ion adsorption (Figure 2).…”

“…Conformations of polyelectrolyte chains play an important functional role [ 20 , 21 , 22 ]. Adsorption of multivalent cations on a polyelectrolyte chain may lead to significant changes in their sizes and conformations [ 23 , 24 , 25 , 26 , 27 , 28 ].…”

Surface polarization effects in confined polyelectrolyte solutions

“…However, for many biological settings as well as in supercapacitor applications, molecular electrolytes confined by dielectric materials, such as graphene, are of interest. Recent studies on dielectric confinement of polyelectrolyte by a spherical cavity showed that dielectric mismatch leads to unexpected symmetry-breaking conformations, as the surface charge density increases (20). The focus of the present study is the collective effects of spatial confinement by two parallel surfaces and dielectric mismatch on the structural features of a polyelectrolyte solution.…”