The usual understanding in polymer electrolyte design is that increasing the polymer dielectric constant results in reduced ion aggregation and therefore increased ionic conductivity. We demonstrate here that in a class of polymers with extensive metal-ligand coordination and tunable dielectric properties, the extent of ionic aggregation is delinked from the ionic conductivity. The polymer systems considered here comprise ether, butadiene, and siloxane backbones with grafted imidazole side-chains, with dissolved Li + , Cu 2+ , or Zn 2+ salts. The nature of ion aggregation is probed using a combination of X-ray scattering, electron paramagnetic resonance (in the case where the metal cation is Cu 2+ ), and polymer field theorybased simulations. Polymers with less polar backbones (butadiene, and siloxane) show stronger ion aggregation in X-ray scattering compared to those with the more polar ether backbone. The Tg-normalized ionic conductivities were however unaffected by extent of aggregation. The results are explained on the basis of simulations which indicate that polymer backbone polarizability does impact the microstructure and the extent of ion aggregation, but does not impact percolation, leading to similar ionic conductivity regardless of the extent of ion aggregation. The results emphasize the ability to design for low polymer Tg through backbone modulation, separately from controlling ion-polymer interaction dynamics through ligand choice.

Microphase separation in a binary blend of oppositely charged polymers can in principle be stabilized electrostatically without the need for connected block polymer architectures. This provides a route to control microstructure via parameters such as polymer charge density, salt concentration, and dielectric constant. Here, we use an equilibrium self-consistent field theory to study the phase behavior of such a binary blend, with or without counterions and added salt, and show that it exhibits the canonical ordered phases of a diblock copolymer melt. We demonstrate how differences in the charge density and the dielectric constant of the two polymers affect phase behavior in this system. In particular, we find that the phase windows for sphere phases are dramatically affected and that the Frank–Kasper phases σ and A15 can be stabilized when the minority component has a higher dielectric constant than the surrounding matrix. Since the domain length scale in this system is determined electrostatically and is not subject to chain-stretching limitations imposed by block architectures, our results suggest a possible route to large-unit-cell complex-sphere phases. These predictions will be most easily tested in oppositely charged polymeric ionic liquids, where the bulky and de-localized charges should aid equilibration in a solvent-free environment.

We study a salt-doped polarizable symmetric diblock copolymer using a recently developed field theory that self-consistently embeds dielectric response, ion solvation energies, and van der Waals (vdW) attractions via the incorporation of segment polarizabilities and fixed dipoles. This field theory is amenable to direct simulation via the complex Langevin sampling technique and, thus, requires no approximations beyond the phenomenology of the underlying molecular model. We measure the shift in the order−disorder transition (ODT) of a diblock copolymer with salt-loading in field-theoretic simulations and observe rich behavior in which solvation, dilution and charge screening effects compete to determine whether the ordered or disordered phase is stabilized. At low salt concentrations, the salt behaves as a selective solvent, localizing into the high-dielectric domains and stabilizing the ordered phase. At high salt concentrations, however, the salt localization vanishes due to charge screening effects, and the salt behaves as a nonselective solvent that screens vdW attractions and stabilizes the disordered phase.

We derive the effective Flory-Huggins parameter in polarizable polymeric systems, within a recently introduced polarizable field theory framework. The incorporation of bead polarizabilities in the model self-consistently embeds dielectric response, as well as van der Waals interactions. The latter generate a χ parameter (denoted χ̃) between any two species with polarizability contrast. Using one-loop perturbation theory, we compute corrections to the structure factor Sk and the dielectric function ϵ^(k) for a polarizable binary homopolymer blend in the one-phase region of the phase diagram. The electrostatic corrections to S(k) can be entirely accounted for by a renormalization of the excluded volume parameter B into three van der Waals-corrected parameters B, B, and B, which then determine χ̃. The one-loop theory not only enables the quantitative prediction of χ̃ but also provides useful insight into the dependence of χ̃ on the electrostatic environment (for example, its sensitivity to electrostatic screening). The unapproximated polarizable field theory is amenable to direct simulation via complex Langevin sampling, which we employ here to test the validity of the one-loop results. From simulations of S(k) and ϵ^(k) for a system of polarizable homopolymers, we find that the one-loop theory is best suited to high concentrations, where it performs very well. Finally, we measure χ̃N in simulations of a polarizable diblock copolymer melt and obtain excellent agreement with the one-loop theory. These constitute the first fully fluctuating simulations conducted within the polarizable field theory framework.

The small specific entropy of mixing of high molecular weight polymers implies that most blends of dissimilar polymers are immiscible with poor physical properties. Historically, a wide range of compatibilization strategies have been pursued, including the addition of copolymers or emulsifiers or installing complementary reactive groups that can promote the in situ formation of block or graft copolymers during blending operations. Typically, such reactive blending exploits reversible or irreversible covalent or hydrogen bonds to produce the desired copolymer, but there are other options. Here, we argue that ionic bonds and electrostatic correlations represent an underutilized tool for polymer compatibilization and in tailoring materials for applications ranging from sustainable polymer alloys to organic electronics and solid polymer electrolytes. The theoretical basis for ionic compatibilization is surveyed and placed in the context of existing experimental literature and emerging classes of functional polymer materials. We conclude with a perspective on how electrostatic interactions might be exploited in plastic waste upcycling.