Dielectric discontinuity in equilibrium block copolymer micelles

Abstract

The surface tension between the hydrophobic core and the solvent is known to play a major role in the self-assembly of diblock copolymer micelles in solution. Coulombic forces are also very important in the case of aggregates with weakly charged coronas. The aggregation number and morphology are often tuned by the addition of electrolytes to the solution via electrostatic screening and an eventual change in solvent quality. However, when the surface tension is low enough, dielectric discontinuity between the core and the solvent becomes important enough in comparison to other mechanisms, driving the surface tension at the same time it screens electrostatic interactions in the corona. Below, we demonstrate the importance of this effect for micelles with neutral and weakly charged coronas.

The electrostatic co-assembly in non-stoichiometric aqueous mixtures of copolymers composed of one neutral water-soluble and one polyelectrolyte (either positively or negatively charged) block: a dissipative particle dynamics study

“…This shape of the distribution function indicates the ''closed association scheme'' observed in experimental studies of analogous electrostatic self-assemblies. 1,6 A non-negligible half-width of the peak of associates (slightly less than 20) can be attributed to the relatively short length of the studied coarse-grained chains and is in agreement with other simulation papers 36 studying polymer self-assembly processes using coarse-grained simulations. 33,62 A pronounced oscillatory character of the curve preferring even to odd association numbers reflects the fact that neutral associates with fully compensated charge are more stable than those with an excess of (positive or negative) charge.…”

“…Simulations show that the small negative ions accumulate mainly in a relatively thick outer layer of the core, but their average density in the core is higher than that in the bulk solvent in systems without added salt. A number of experimental papers on electrostatic self-assembly 1,4,6,12,73,74 indicate that the counterions are usually compatible to some extent with the core-forming polymer blocks. Investigation of the role of ions in electrostatic self-assembly is therefore very important.…”

“…have been studied experimentally with respect to their potential use in biomedical and environmental fields. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]82,83 Several interesting multifunctional PIC-based systems, which certainly deserve to be mentioned, have been synthesized, carefully characterized and studied in detail recently. [84][85][86] However, experimentalists are limited by the feasibility of the synthesis of suitable samples and their main interest is in the development and optimization of stable systems with targeted functional properties and therefore systematic studies of systems differing in composition, in the strength of interactions between components, etc.…”

“…It is impossible to mention all the relevant studies and therefore we have included only the most important reviews and a few interesting recent papers. [1][2][3][4][5][6][7][8][9][10] The popularity of electrostatically stabilized interpolyelectrolyte complexes (IPECs) is derived from the fact that they can be used as carriers of different compounds solubilized in their cores, similarly to aqueous dispersions of amphiphilic block copolymer micelles. However, in contrast to common block copolymer micelles with nonpolar cores, IPECs can solubilize a number of quite polar compounds.…”

On Capacitance and Energy Storage of Supercapacitor with Dielectric Constant Discontinuity

“…Understanding the surface polarization effect can increase our ability to control the EDL structure and disclose work mechanisms for many practical applications, such as the design of a supercapacitor (SC) [ 25 , 26 , 27 , 28 ], modulating three-dimensional conformation of polyelectrolyte brush [ 29 ], self-assembly [ 30 , 31 ], ionic profiles [ 22 , 23 , 32 ], and surface force [ 21 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”