Polymer Salt Research Articles

Synergistic effect of ceramic filler in polymer salt complex for improved ion dissociation and migration mechanism

Abstract Use of Ceramic filler is one of the most common approaches to improve the conductivity and stability properties of a solid polymer electrolyte (SPE) cum separator. Among them, active fillers like Garnet have been extensively used to enhance the stability and conductivity of SPE. However, SPE suffers from limited ion migration at room temperature acting as a bottleneck for their application in all solid-state batteries. An extensive study on these fillers' role in ion dissociation and migration can be a stepping stone for advanced SPE. In the present work, an FTIR analysis has primarily been used to identify and evaluate cation coordinate site-cation, and ion pair interactions in a Li6.5La3Zr1.75Te0.25O12 loaded polyethylene oxide-LiCF3SO3 matrix with varying ceramic concentrations. Further, the Trukhan model has been used to calculate diffusion coefficient, mobility, and charge carrier density to interpret relaxation parameters, conductivity, and FTIR results in the SPE samples. Finally, an ion migration model has been proposed based on the results obtained in experimental studies.

Synthesis and Polymerization of Poly Acryl Imide and One of Their Derivatives Then Curing the Product with Alkyl Halide

The present work involved four steps: First step include reaction of acrylamide ,N-?-Methylen-bis(acryl amide) and N-tert Butyl acryl amide with poly acryloyl chloride in the presence of triethyl amine (Et3N) as catalyst, the second step include homopolymerization of all products of the first step by using benzoyl peroxide(BPO) as initiator in (80-90)Co in the presence of Nitrogen gas(N2). In the third step the poly acrylimide which prepare in second step was convert into potassium salt by using alcoholic potassium hydroxide solution. Fourth step include Alkylation of the prepared polymeric salts in third step by react it with different alkyl halides(benzyl chloride, allylbromide , methyl iodide) by using DMF as solvent for(10-12) hours. Structure Confirmation of all prepared polymers were proved using FT-IR, 1H-NMR and C13-NMR spectroscopy for some polymers. Other physical properties including softening and melting points of the polymers were also measured.

Hydrodynamic Analysis of Polymer–Salt Aqueous Two-Phase Systems in a Millifluidic Channel

Hydrodynamic Analysis of Polymer–Salt Aqueous Two-Phase Systems in a Millifluidic Channel

Dynamic density functional theory of polymers with salt in electric fields.

We present a dynamic density functional theory for modeling the effects of applied electric fields on the local structure of polymers with added salt (polymer electrolytes). Time-dependent equations for the local electrostatic potential and volume fractions of polymer, cation, and anion of added salt are developed using the principles of linear irreversible thermodynamics. For such a development, a field theoretic description of the free energy of polymer melts doped with salts is used, which captures the effects of local variations in the dielectric function. Connections of the dynamic density functional theory with experiments are established by relating the three phenomenological Onsager's transport coefficients of the theory to the mutual diffusion of electrolyte, ionic conductivity, and transference number of one of the ions. The theory is connected with a statistical mechanical model developed by Bearman and Kirkwood [J. Chem. Phys. 28, 136 (1958)] after relating the three transport coefficients to friction coefficients. The steady-state limit of the dynamic density functional theory is used to understand the effects of dielectric inhomogeneity on the phase separation in polymer electrolytes. The theory developed here provides not only a way to connect with experiments but also to develop multi-scale models for studying connections between local structure and ion transport in polymer electrolytes.

Flexible magnesium-ion-conducting solid poly-blend electrolyte films for magnesium-ion batteries

Solid biodegradable polymer electrolyte systems are considered the optimal choice for energy storage devices because they are both cost-effective and energy-efficient. A solid blend polymer electrolyte (SBPE) membrane capable of transporting magnesium ions was prepared using a mixture of 70 wt% methylcellulose, 30 wt% chitosan, and varying wt% magnesium perchlorate salt. X-ray diffraction analysis revealed an increase in the amorphous nature caused by the inclusion of Mg(ClO4)2 salt in the polymer blend matrix. A Fourier transform infrared spectroscopy study of samples containing varying salt concentrations revealed secondary interactions between polymer segments and salt, which provides the basis for energy density. Moreover, through impedance analysis, it was determined that the bulk resistance decreased with increasing salt concentration. The SBPE containing 30 wt% magnesium perchlorate exhibited the highest ionic conductivity, with a value of 2.49 × 10–6 S cm−1. A comprehensive evaluation of the ion transport parameters, including mobility, carrier density, and diffusion, was conducted for the prepared electrolyte samples. Notably, an ionic transference number (tion) of approximately 0.83 was observed for the SBPE sample with 30 wt% magnesium salt, indicating ions’ prevalence as the system’s primary charge carriers. Electrochemical analyses demonstrated that the SBPE with the highest ion conductivity possessed an electrochemical stability window (ESW) of 1.92 V. Additionally, the thermal characteristics of the samples were evaluated using thermogravimetric analysis (TGA) to assess the thermal stability of the electrolyte. Finally, the highest conducting polymer electrolyte was employed to construct a primary magnesium battery, and its discharge profile with different cathode materials was studied. Based on these findings, the current study suggests an environmentally friendly, biodegradable, and economically viable electrolyte option suitable for separator cum electrolytes in magnesium-ion batteries.

Model for predicting oil testing fluid rheological parameters of Bohai Bay oilfield in wide temperature and pressure range

The rheological parameters of oil testing fluids play a crucial role in safely conducting oil testing operations, protecting reservoirs, and maintaining wellbore integrity, which are greatly influenced by temperature and pressure. This article conducted rheological experiments on commonly used potassium salt polymer systems and organic salt systems for oil testing fluids in the Bohai Bay Oilfield under 4–200 °C and 30–150 MPa. The experiments revealed the variation of rheological parameters with temperature and pressure. Nine commonly used rheological models were evaluated for their applicability to the two types of oil testing fluids. It was found that the Ross model was suitable for the potassium salt polymer system, while the power-law model was suitable for organic salt oil testing fluids. A new rheological parameter prediction model suitable for wide range of temperature and pressure and different testing fluid systems was proposed based on the optimized results. The average error for the potassium salt polymer system for oil testing fluids was 0.101%, and the error for the organic salt system for oil testing fluids was 0.113%. Both were superior to known rheological models and can meet the requirements of oil testing operations within the wide temperature and pressure range in the Bohai Bay Oilfield.

Realizing highly conductive “polymer in salt” electrolytes through Li-ion-highway for room temperature all-solid-state Li-S batteries

“Polymer in salt” electrolytes (PISEs) have great application prospects because of their higher ionic conductivity than conventional solid polymer electrolytes (SPEs) at room temperature. However, it is still a challenge to realize both high ionic conduction and mechanical properties for PISEs. Here we address the issue by comprising interconnected ultra-long MnO2 nanowires modified with (3-Aminopropyl)trimethoxysilane (AMW) in PAN-LiTFSI-based PISEs. The presence of AMW reinforces the mechanical properties and aids Li-ion migration between ionic aggregates through a “hand-to-hand” mode. The resulting electrolyte (PIS-AMW) exhibits a high tensile strength of 2.77 MPa, ionic conductivity of 4.44 × 10−4 S cm−1 and Li-ion transference number of 0.61 at 25 °C. Li symmetric cells assembled with PIS-AMW demonstrate satisfactory cycling stability for up to 600 h. All-solid-state lithium‑sulfur batteries assembled with this electrolyte exhibit a capacity of 643 mAh g−1 at 0.05C and 25 °C after 80 cycles. The strategy effectively resolves the dilemma between long-range ionic conduction and mechanical properties in PISEs, which have potential applications in high-energy-density solid-state batteries.

Metal-Halogen Interactions Inducing Phase Separation for Self-Healing and Tough Ionogels with Tunable Thermoelectric Performance.

Ionic liquid-based thermoelectric gels become a compelling candidate for thermoelectric power generation and sensing due to their giant thermopower, good thermal stability, high flexibility, and low-cost production. However, the materials reported to date suffer from canonical trade-offs between self-healing ability, stretchability, strength, and ionic conductivity. Herein, a self-healing and tough ionogel (PEO/LiTFSI/EmimCl) with tunable thermoelectric properties by tailoring metal-halogen bonding interactions, is developed. Different affinities between polymer matrix and salts are exploited to induce phase separation, resulting in simultaneous enhancement of ionic conductivity and mechanical strength. Molecular dynamics (MD) simulations and spectroscopic analyses show that Cl- ions impair the lithium-ether oxygen coordination, leading to changes in chain conformation. The migration difference between cations and anions is thus widened and a transition from n-type to p-type thermoelectric ionogels is realized. Furthermore, the dynamic interactions of metal-ligand coordination and hydrogen bonding yield autonomously self-healing capability, large stretchability (2000%), and environment-friendly recyclability. Benefiting from these fascinating properties, the multifunctional PEO-based ionogels are applied in sensors, supercapacitors, and thermoelectric power generation modules. The strategy of tuning solvation dominance to address the trade-offs in thermoelectric ionogels and optimize their macroscopic properties offers new possibilities for the design of advanced ionogels.

Effect of CdS on the Electrical Conductivity of Polyvinyl Alcohol (PVA) and Potassium Iodide (KI) thin films

In the past two decades, solid polymer electrolytes (SPEs) have attracted attention as a platform for electrochemical devices. Here polymer-based electrolytes have the advantage that they can be grown in a thin film, plus they are leak-proof. In the present work, we have used PVA:KI as the host polymer–salt complex with a composition of 85:15. Further, this PVA:KI complex dispersed with different wt% of CdS. Standard solution cast techniques have been used for thin film preparation. All prepared samples are characterized to study conductivity and structural changes. A maximum ionic conductivity of 2.47 X 10-7 S/cm was observed for 9wt% of CdS. Also, the band gap of these films was calculated and found to be between 2.4 to 2.9 eV. Also, the concentration and mobility of charge carriers were calculated to explain the change in conductivity pattern. This calculation was performed with the Schutt & Gerdes model. It is observed that the conductivity pattern mainly follows the concentration of charge carriers. DOI: https://doi.org/10.52783/pst.370

Silica-Poly(Vinyl Alcohol) Composite Aerogel: A Promising Electrolyte for Solid-State Sodium Batteries.

The transition from fossil fuels is in part limited by our inability to store energy at different scales. Batteries are therefore in high demand, and we need them to store more energy, be more reliable, durable and have less social and environmental impact. Silica-poly(vinyl alcohol) (PVA) composite aerogels doped with sodium perchlorate were synthesized as novel electrolytes for potential application in solid-state sodium batteries. The aerogels, synthesized by one-pot synthesis, are light (up to 214 kg m-3), porous (~85%), exhibit reduced shrinkage on drying (up to 12%) and a typical silica aerogel microstructure. The formation of a silica network and the presence of PVA and sodium perchlorate in the composite were confirmed by FTIR and TGA. The XRD analysis also shows that a predominantly amorphous structure is obtained, as crystalline phases of polymer and salt are present in a very reduced amount. The effects of increasing polymer and sodium salt concentrations on the ionic conductivity, assessed via electrochemical impedance spectroscopy, were studied. At a PVA concentration of 15% (w/w silica precursors), the sodium conduction improved significantly up to (1.1 ± 0.3) × 10-5 S cm-1. Thus, this novel material has promising properties for the envisaged application.

Structural investigation of solid biopolymer electrolytes: 2-hydroxyethyl cellulose doped ammonium formate as a promising proton conductor

Fabrication of solid biopolymer electrolytes (SBEs) was mainly to cater the drawbacks of lithium-ion electrolytes in terms of leakage, high cost, and toxic material. In this present work, solid biopolymer electrolytes system comprises of 2-Hydroxyethyl Cellulose (2-HEC) as polymer host, and various weight percentage (wt.%) of Ammonium Formate (AF) as ionic doping salt are produced by using solution casting technique. The relation between structural and ionic conductivity of 2-HEC/AF was analyzed and investigated by using X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Electrical Impedance Spectroscopy (EIS). Through the analysis of XRD, it can be observed that the amorphous region of SBEs increases as the concentration of AF salt increases. The amorphous region of SBEs can be confirmed due to the interaction of salt concentration and polymer. However, in this present work, the broadest peak in XRD of the sample does not necessarily correlate with the highest conductivity among the samples. The interaction between polymer-salt complexes is proved through FTIR spectrum at the range of 700 cm−1 to 1300 cm−1. The highest ionic conductivity of 2-HEC/AF achieved is 2.40 × 10−3 S/cm at room temperature for SBEs containing 40 wt.% of AF. The findings from this study made it clear that the concentration of Ammonium Formate salt affects the increase in ionic conductivity.

Poly(vinyl benzoate)-b-poly(diallyldimethyl ammonium TFSI)-b-poly(vinyl benzoate) Triblock Copolymer Electrolytes for Sodium Batteries

Block copolymers (BCPs) as solid electrolytes for batteries are usually designed to have an ion-solvating block for ion conduction and an ionophobic block for providing mechanical strength. Here, we show a novel solid polymer electrolyte (SPE) for sodium batteries based on a poly(vinyl benzoate)-b-poly(diallyldimethyl ammonium bis(trifluoromethanesulfonyl)imide) PVBx-b-PDADMATFSIy-b-PVBx ABA triblock copolymer. The SPE triblock copolymer comprises a polymerized ionic liquid (PIL) ion-solvating block combined with NaFSI salt as an internal block and an ionophilic PVB as an external block. Four distinct compositions with varying chain lengths of the blocks were synthesized by reversible addition−fragmentation chain-transfer (RAFT) polymerization. The neat copolymers were subsequently mixed with NaFSI in a 2:1 mol ratio of Na to ionic monomer units. Through comprehensive analysis using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR), it was revealed that the ion coordination within the polymer–salt mixtures undergoes changes based on the composition of the starting neat polymer. Electrochemical evaluations identified the optimal composition for practical application as PVB11.5K-b-PDADMATFSI33K-b-PVB11.5K, showing an ionic conductivity at 70 °C of 4.2 × 10−5 S cm−1. This polymer electrolyte formulation was investigated for sodium in Na|Na symmetrical cells, showing an overpotential of 200 mV at 70 °C at 0.1 mA cm−2. When applied in a sodium–air battery, the polymer electrolyte membrane achieved a discharge capacity of 1.59 mAh cm−2 at 50 °C.

Anion-modulated Ion Conductor with Chain Conformational Transformation for stabilizing Interfacial Phase of High-Voltage Lithium Metal Batteries.

In solid-state lithium metal batteries (SSLMBs), the inhomogeneous electrolyte-electrode interphase layer aggravates the interfacial stability, leading to discontinuous interfacial ion/charge transport and continuous degradation of the electrolyte. Herein, we constructed an anion-modulated ionic conductor (AMIC) that enables in situ construction of electrolyte/electrode interphases for high-voltage SSLMBs by exploiting conformational transitions under multiple interactions between polymer and lithium salt anions. Anions modulate the decomposition behavior of supramolecular poly (vinylene carbonate) (PVC) at the electrode interface by changing the spatial conformation of the polymer chains, which further enhances ion transport and stabilizes the interfacial morphology. In addition, the AMIC weakens the "Li+-solvation" and increases Li+ vehicle sites, thereby enhancing the lithium-ion transport number (tLi +=~0.67). Consequently, Li || LiNi0.8Co0.1Mn0.1O2 cell maintains about 85 % capacity retention and Coulombic efficiency >99.8 % in 200 cycles at a charge cut-off voltage of 4.5 V. This study provides a new understanding of lithium salt anions regulating polymer chain segment behavior in the solid-state polymer electrolyte (SPE) and highlights the importance of the ion environment in the construction of interfacial phases and ionic conduction.

A Biomimetic "Salting Out-Alignment-Locking" Tactic to Design Strong and Tough Hydrogel.

Recently, hydrogel-based soft materials have demonstrated huge potential in soft robotics, flexible electronics as well as artificial skins. Although various methods are developed to prepare tough and strong hydrogels, it is still challenging to simultaneously enhance the strength and toughness of hydrogels, especially for protein-based hydrogels. Herein, a biomimetic "salting out-alignment-locking" tactic (SALT) is introduced for enhancing mechanical properties through the synergy of alignment and the salting out effect. As a typical example, tensile strength and modulus of initially brittle gelatin hydrogels increase 940 folds to 10.12±0.50MPa and 2830 folds to 34.26±3.94MPa, respectively, and the toughness increases up to 1785 folds to 14.28±3.13MJ m-3. The obtained strength and toughness hold records for the previously reported gelatin-based hydrogel and are close to the tendons. It is further elucidated that the salting out effect engenders hydrophobic domains, while prestretching facilitates chain alignment, both synergistically contributing to the outstanding mechanical properties. It is noteworthy that the SALT demonstrates remarkable versatility across different salt types and polymer systems, thus opening up new avenues for engineering strong, tough, and stiff hydrogels.

Highly Macroporous Polyimide with Chemical Versatility Prepared from Poly(amic acid) Salt-Stabilized High Internal Phase Emulsion Template.

Macroporous polymers have gained significant attention due to their unique mass transport and size-selective properties. In this study, we focused on Polyimide (PI), a high-performance polymer, as an ideal candidate for macroporous structures. Despite various attempts to create macroporous PI (Macro PI) using emulsion templates, challenges remained, including limited chemical diversity and poor control over pore size and porosity. To address these issues, we systematically investigated the role of poly(amic acid) salt (PAAS) polymers as macrosurfactants and matrices. By designing 12 different PAAS polymers with diverse chemical structures, we achieved stable high internal phase emulsions (HIPEs) with >80 vol % internal volume. The resulting Macro PIs exhibited exceptional porosity (>99 vol %) after thermal imidization. We explored the structure-property relationships of these Macro PIs, emphasizing the importance of controlling pore size distribution. Furthermore, our study demonstrated the utility of these Macro PIs as separators in Li-metal batteries, providing stable charging-discharging cycles. Our findings not only enhance the understanding of emulsion-based macroporous polymers but also pave the way for their applications in advanced energy storage systems and beyond.

A Partial Metal Coordination Strategy toward High‐Performance and Cost‐Effective Electron Transporting Layer for Organic Solar Cells

Additives are frequently employed in the active layer of organic solar cells (OSCs) to fine‐tune morphology and improve overall device performance. The use of additive in electron transporting layer (ETL) has garnered less attention. In this study, poly(2‐vinyl pyridine) (P2VP) based cost‐effective ETLs are developed for OSCs. Addition of CoCl2 to the P2VP affords ETLs with enhanced conductivity and optimized work function. OSCs employing this ETL demonstrate prolonged carrier lifetime, suppressed charge recombination, and achieve higher power conversion efficiencies (PCEc) than the commonly used ETLs such as PFNBr and Phen‐NaDPO. The cost of the P2VP‐Co is merely one‐twentieth of that associated with Phen‐NaDPO or PFNBr. Mechanism studies and density functional theory (DFT) calculations reveal that the partial metal salt coordination of P2VP leaves free pyridine rings for dipole interactions with the Ag electrode, and provides higher electrostatic potentials and larger dipole moments compared to the polymer alone, thereby increasing conductivity. The polymer and metal salt additive strategy demonstrates its effectiveness in boosting device performance, offering valuable possibility for designing novel electronic materials and expanding the applications of widely available polymers.

Anion‐modulated Ion Conductor with Chain Conformational Transformation for Enhanced Interfacial Phase Stabilization of High‐Voltage Lithium Metal Batteries

In solid‐state lithium metal batteries (SSLMBs), the inhomogeneous electrolyte‐electrode interphase layer aggravates the interfacial stability, leading to discontinuous interfacial ion/charge transport and continuous degradation of the electrolyte. Herein, we constructed an anion‐modulated ionic conductor (AMIC) that enables in‐situ construction of electrolyte/electrode interphases for high‐voltage SSLMBs by exploiting conformational transitions under multiple interactions between polymer and lithium salt anions. Anions modulate the decomposition behavior of supramolecular poly(vinylidene chloride) (PVC) at the electrode interface by changing the spatial conformation of the polymer chains, which further enhances ion transport and stabilizes the interfacial morphology. In addition, the AMIC weakens the “Li+‐solvation” and increases Li+ vehicle sites, thereby enhancing the lithium‐ion transport number (tLi+ = ~0.67). Consequently, Li||LiNi0.8Co0.1Mn0.1O2 cell maintains about 85% capacity retention and Coulombic efficiency > 99.8% in 200 cycles at a charge cut‐off voltage of 4.5V. This study provides a new understanding of lithium salt anions regulating polymer chain segment behavior in the SPE and highlights the importance of the ion environment in participating in the construction of interfacial phases and ionic conduction.

Hybrid Electrolyte Based on PEO and Ionic Liquid with In Situ Produced and Dispersed Silica for Sustainable Solid-State Battery

This work introduces the synthesis of hybrid polymer electrolytes based on polyethylene oxide (PEO) and electrolyte solution bis(trifluoromethane)sulfonimide lithium salt/ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (LiTFSI/EMIMTFSI) with in situ produced and dispersed silica particles by the sol–gel method. Conventional preparation of solid polymer electrolytes was followed by desolvation of lithium salt in a polymer matrix of PEO, which, in some cases, additionally contains plasticizers. This one-pot synthesis is an alternative route for fabricating a solid polymer electrolyte for solid-state batteries. The presence of TFSI- reduces the crystallinity of the PEO matrix (plasticizing effect), increases the dissociation and solubility of LiTFSI in the PEO matrix because of a highly delocalized charge distribution, and reveals excellent thermal, chemical, and electrochemical stability. Tetraethylorthosilicate (TEOS) was chosen due to the slow reaction rate, with the addition of (3-glycidyoxypropyl)trimethoxysilane (GLYMO), which contributes to the formation of a silica network. FTIR studies confirmed the interactions between the silica, the polymer salt, and EMIMTFSI. Impedance spectroscopy measurements were performed in a wide range of temperatures from 25 to 70 °C. The electrochemical performance was explored by assembling electrolytes in LiCoO2 (LCO), NMC(811), and LiFePO4 (LFP) coin half-cells. The HPEf15 shows a discharge capacity of 143 mA/g for NMC(811) at 0.1 C, 134 mA/g for LCO, and 139 mA/g for LFP half-cells at 0.1 C and 55 °C. The LFP half-cell with a discharge capacity of 135 mA/g at 0.1 C (safety potential range of 2.8 to 3.8) obtained a cyclability of 97.5% at 55 °C after 100 cycles. Such a type of electrolyte with high safety and good electrochemical performance provides a potential approach for developing a safer lithium-ion battery.

Synergistic combination of ether-linkage and polymer-in-salt for electrolytes with facile Li+ conducting and high stability in solid-state lithium batteries

In developing solid polymer electrolytes (SPEs), networked SPE (NSPE) and polymer-in-salt (PiS) configurations are effective strategies to achieve high ionic conductivity. The ether linkage of poly(ethylene oxide) (PEO) effectively dissociates salts, among which salt Li[N(SO2F)2] (LiFSI) exhibits excellent Li+-conductive characteristics. The present study synthesizes a PiS-NSPE comprising 55 wt% LiFSI and 45 wt% PEO-based NSPE. The PiS configuration creates aggregated Li+n-FSI−m domains for Li+ transport through the decoupling ion-conductive mechanism and the NSPE, with high-voltage tolerance, dissociates LiFSI and segregates the Li+n-FSI−m domains into interconnected clusters for Li+ percolation. With such a synergistic combination, the PiS-NSPE exhibits an ionic conductivity of 2.3 × 10−3 S cm−1 and a Li+-transference number of 0.69 at 30 ℃. Protected by LiFSI, the PiS-NSPE is electrochemically stable until 4.6 V (vs. Li/Li+). The elastic feature enables the PiS-NSPE to withstand the Li-anode volume change and the lithiophilic FSI−-derived interlayer facilitates smooth Li deposition. The high compatibility between the PiS-NSPE and electrode materials results in the excellent performance of commercial-scale cathodes (∼10 mg cm−2 in active mass) in batteries. The synergy between PEO-based NSPEs and high-content LiFSI is promising in realizing the practical application of SPEs in all-solid-state batteries.

Segregative phase separation of strong polyelectrolyte complexes at high salt and high polymer concentrations.

The phase behavior of polyelectrolyte complexes and coacervates (PECs) at low salt concentrations has been well characterized, but their behavior at concentrations well above the binodal is not well understood. Here, we investigate the phase behavior of stoichiometric poly(styrene sulfonate)/poly(diallyldimethylammonium) mixtures at high salt and high polymer concentrations. Samples were prepared by direct mixing of PSS/PDADMA PECs, water, and salt (KBr). Phase separation was observed at salt concentrations approximately 1 M above the binodal. Characterization by thermogravimetric analysis, FTIR, and NMR revealed that both phases contained significant amounts of polymer, and that the polymer-rich phase was enriched in PSS, while the polymer-poor phase was enriched in PDADMA. These results suggest that high salt concentrations drive salting out of the more hydrophobic polyelectrolyte (PSS), consistent with behavior observed in weak polyelectrolyte systems. Interestingly, at the highest salt and polymer concentrations studied, the polymer-rich phase contained both PSS and PDADMA, suggesting that high salt concentrations can drive salting out of partially-neutralized complexes as well. Characterization of the behavior of PECs in the high concentration limit appears to be a fruitful avenue for deepening fundamental understanding of the molecular-scale factors driving phase separation in these systems.