Ionic Domains Research Articles

Enhancement of hydroxide conductivity by incorporating nanofiber-like palygorskite into quaternized polysulfone as anion exchange membranes

The natural hydrophilic nanofiber-like palygorskite (Pal) particles were incorporated into the quaternary ammonium functionalized polysulfone (QPSf) to prepare high performance anion exchange membranes. Due to the mutual compatibility between quaternary ammonium groups in quaternized polysulfone and hydrophilic Pal particles, a hydrophilic domain could aggregate, thereby forming a hydrophilic-hydrophobic microphase separation structure. Meanwhile, the small-angle X-ray scattering (SAXS) was utilized to characterize the hydrophilic ionic cluster domain in the composite membrane. The results showed that the corresponding average inter-domain spacing of the QPSf/Pal-0.5 membrane was about 30 nm. Then, the new composite membrane had not only highly efficient hydrophilic ion transport channels but also adjustable hydrophilic-hydrophobic microphase separation structures. Compared with original quaternized polysulfone membranes, the hydroxide conductivity of the QPSf/Pal-0.5 membrane reached 93.0 mS·cm−1 at 80 °C, increasing by 48%, while the methanol permeability was kept between 4.2 × 10−7 and 5.8 × 10−7 cm2·s−1.

Adaptive Deformation of Ionic Domains in Hydrogel Enforcing Dielectric Coupling for Sensitive Response to Mechanical Stretching

Understanding the role of ionic migration in salt‐doped hydrogels is crucial for designing and using ionic skins. This study systematically investigates a typical ionic skin in the aspects of variations in capacitance and conductance with respect to stretch ratio. The ionic skin exhibits a sensitive response to the stretch ratio and input frequency. The capacitance can increase by 145% with increasing stretch ratio, whereas the ratio of capacitance variation to stretch ratio can exceed ≈0.25. The capacitance decreases with increasing frequency, whereas conductance increases. Capacitance or conductance with respect to stretch ratio exhibits an inflection point when the input frequency is fixed. Herein, an ionic domain model is proposed in which the ionic domains deform adaptively with global strain and released active ions. A portion of movable ions strengthens dielectric coupling, thereby significantly enhancing capacitance, and some of them act as free ion channels to increase conductance. The dielectric coupling is weakened when the active ions arriving at the electrode are depleted by either a significantly high frequency or large strain. This study will be useful for signal handling in ionic skin with high flux and high sensitivity and may also assist in understanding computing and memory principles of biological bodies.

Peptide-Controlled Assembly of Anion Exchange Ionomer Thin Films on Electrode Surfaces for Promoting Microphase Separation and Ionic Conductivity

In electrochemical devices such as water electrolyzers and fuel cells, the network and morphology of the conductive ionomers within electrodes are critical for ion delivery and mass transport, significantly influencing the device performance. Most studies investigate these materials as bulk polymer electrolyte membranes and comparatively little attention has been given to their behavior on electrode surfaces as thin films. Anion exchange membrane fuel cells and water electrolyzers (AEMFCs and AEMWEs) would allow the use of non-precious group metals and enable low-cost systems, yet, even less is known about thin films of anion exchange ionomer (AEI). Protein engineering is emerging as a powerful nanomanufacturing tool to control the organization of components on electrodes. In this work, we propose that it can be applied to ionomer control, demonstrating that sequence defined elastin-like peptides assembled on electrode surfaces, and/or solvent vapor annealing processing, alters the microstructure configuration of assembled thin films of anion exchange ionomer. It is observed that peptides form a uniform monolayer on the metal surface, and moderately sized microphase separated ionic domains of the AEI are obtained either by modifying the electrode with peptides or solvent vapor annealing, which correlate with an increased in-plane ionic conductivity of the thin film. Interestingly, the use of peptide-modified electrodes in conjunction with solvent vapor annealing yields excessively large ionic grains that correlates with compromised ionic conductivity. Overall, we show that sequence defined peptides could serve as a tool for controlling electrode architecture, and judicious use of peptides, or solvent vapor annealing, have the potential to control the microstructure of thin AEI films and lead to structure-function understanding.

On the physico-chemical basis of self-nanosegregation giving magnetically-induced birefringence in dibutyl phosphate/bis(2-ethylhexyl) amine systems

Dibutyl phosphate (DBP)/bis(2-ethylhexyl) amine (BEEA) liquid mixtures can show optical birefringence when exposed to a magnetic field. It has been hypothesized that this is a consequence of self-segregation characterizing these systems giving formation of anisotropic local assemblies which are able to re-orient under magnetic field. In this work, an ab-initio Density Functional Theory computer modeling coupled with synchrotron X-Ray Scattering (XRS) experiments carried out at various BEEA molar ratio (X) and temperatures (10 ≤ T ≤ 60 °C) permitted to highlight the physical origin of this effect: a DBP-to-BEEA proton transfer with formation of an inherently anisotropic DBP-BEEA ion pair constituting the building block of highly structured ionic liquid nanodomains. At non-equimolar compositions (X ≠ 0.5) such ionic liquids domains are dispersed in the component in excess. At X > 0.5 the ionic liquids nanodomains are dispersed in excess of poorly structured BEEA, creating the ideal assumptions for the formation of a two-phase dispersed system, as confirmed by Guinier analysis in the small angle regime of the XRS spectra, explaining the system capability to become birefringent in reaction to external magnetic field.These information can be transferred to other amphiphiles-based mixtures for the piloted design of new magnetic field responsive materials with advanced applications.

Morphology Changes in Perfluorosulfonated Ionomer from Thickness and Thermal Treatment Conditions.

The morphological changes of Nafion thin films with thicknesses from 10 to 200 nm on Pt substrate with various annealing histories (unannealed to 240 °C) were systematically investigated using grazing incidence small-angle X-ray scattering (GISAXS) and grazing incidence wide-angle X-ray scattering (GIWAXS). The results revealed that the hydrophilic ionic domain and hydrophobic backbone in Nafion thin films changed significantly when the annealing treatment exceeded the cluster transition temperature, which decreased proton conductivity, due to the constrained hydrophilic/hydrophobic phase separation, and increased the crystalline-rich domain. This research contributed to the understanding of ionomer thermal stability in the catalyst layer, which is subjected to thermal annealing during the hot-pressing process.

Barrier properties of sulfonated polysulfone/layered double hydroxides nanocomposite membrane for direct methanol fuel cell operating at high methanol concentrations

High performing and cost effective nanocomposite membranes for DMFC application are synthesized by incorporating hygroscopic layered double hydroxides (LDH) particles into sulfonated polysulfone (sPSU). A significant improvement in the dimensional stability as well as in the water and methanol molecular dynamics of the sPSU_LDH composite membrane is observed in comparison with both pristine sPSU and Nafion 212. The strong electrostatic interaction occurring between positively charged LDH platelets and negatively charged polymer chains of sPSU alters the microstructure of the ionic domains, allowing an effective reduction of the methanol permeability whilst improving the proton conductivity. The methanol crossover measurements confirmed that sPSU_LDH membranes are able to withstand high methanol concentration without significant aftermath on the chemical stability of the electrolyte. The features enable the single DMFC assembled with the sPSU_LDH nanocomposite to achieve the remarkable power density of 150 mW cm−2 at 80 °C in 5 M methanol solution.

Comb-shaped fluorene-based poly(arylene ether sulfone nitrile) as anion exchange membrane

A series of comb-shaped fluorene-based poly (arylene ether sulfone nitrile) (CFPESN–x) was synthesized as anion exchange membranes (AEMs). The well-designed architecture of fluorene-based main chains and comb-shaped C8 long alkyl side chains containing quaternary ammonium groups was responsible for the clear microphase-separated morphologies, as confirmed by small angle X-ray scattering and atomic force microscopy. Moreover, nitrile groups on main chains also showed a profound influence on membrane morphology and properties. CFPESN–x exhibited more interconnected ionic domains with increasing the nitrile group content resulting in higher conductivities and anti-swelling property. Then CFPESN–x exhibited high ionic conductivities in the range of 27.1–91.5 mS cm−1 from 30 to 80 °C and superior ratios of conductivity to swelling ratio at 80 °C at moderate IECs. Moreover, CFPESN–x also showed good mechanical properties and thermal stability, and optimizable alkaline stability and single cell performance.

Structure-property relationships of tailored imidazolium- and pyrrolidinium-based poly(ionic liquid)s. Solid-like vs. gel-like systems

In this paper, we present facile synthetic strategies enabling production of well-defined poly(ionic liquids) PILs based on 1-vinyl-4-benzyl-3-methylimidazolium- (VBIm) and 1-vinyl-4-benzyl-3-methylpyrrolidium (VBPy) ionic liquids (IL) possessing different counterions (chloride Cl−vs. bis(trifluoromethanesulfonyl)imide NTf2-) (VBIm/NTf2,VBIm/Cl, VBPy/NTf2,VBPy/Cl). The reaction routes have been selected to design two types of polyelectrolytes i) linear homopolymers showing solid-like behavior and ii) grafted copolymers composing of poly(siloxane) segments extended with analogous ionic domains that shows gel-like behavior. The former one has been produced via controlled radical polymerization methods (CRP) such as atom transfer radical polymerization (ATRP) or reversible addition fragmentation chain-transfer polymerization (RAFT), whereas the second one using thiol-ene coupling photo-polymerization. It was found that the glass transition temperature, Tg, of the synthesized herein linear homopolymer-based systems (both VBIm/NTf2 and VBPy/NTf2- -based) increases with their molecular weight, Mn, similarly as reported for its N-conjugated analogs described in our previous study [Maksym et al.,Polym. Chem., 2017, 8, 5433]. However, they are characterized by markedly lower conductivity, σdc (σdc~10−15 S/cm vs.σdc~10−16S/cm for PVBIm/NTf2vs. PVBPy/NTf2- at Tg determined from calorimetric experiments) when compared to N-conjugated one (σdc~10−9 S/cm for poly(N-vinyl-imidazole)/NTf2). Interestingly, the ionic conductivity value at Tg of grafted is similar to its corresponding linear analogs. Nevertheless, at T = 293K both anhydrous linear and grafted imidazolium-based PILs are characterized by high σdc, reaching values σdc~10−4S/cm and σdc~10−7S/cm, respectively.

Hydration Effects on the Permselectivity-Conductivity Trade-Off in Polymer Electrolytes

Polymer electrolytes, which are commonly used as separator materials in electrochemical devices, have ionic conductivity that is thought to be controlled by segmental mobility. Thus, any improvements made toward increasing ionic mobility come at the expense of mechanical integrity. However, selectively solvating the ionic domain, the region responsible for ion conduction, with water or polar organic solvents presents a potential opportunity to circumvent this physical constraint. Here, we explore the role of hydration on the transport properties of membranes formed from randomly sulfonated polystyrene (PS-r-sPS). We find that the water volume fraction underpins an intrinsic trade-off between separator permselectivity (Ψm) and ion conductivity (κ)—thus, improvements in ion diffusion because of increased water content come at the expense of charge density in the membrane which yields a reduced Ψm. We provide a summary of the Ψm–κ trade-off for a suite of commercially available separators to elucidate struct...

SAXS signature of the lamellar ordering of ionic domains of perfluorinated sulfonic-acid ionomers by electric and magnetic field-assisted casting.

At present, small angle X-ray scattering (SAXS) studies of perfluorinated sulfonic-acid ionomers (PFSAs) are unable to fully determine the true shape of their building blocks, as recent SAXS modelling predicts disk- and rod-like nanoionic domains as being equally possible. This scenario requires evidence-based findings to unravel the real shape of PFSA building blocks. Herein, a SAXS pattern signature for a lamellar nanophase separation of the ionic domains of Nafion is presented, backed by mid and far infrared spectroscopy (MIR and FIR) and wide angle X-ray scattering (WAXS) data of Nafion in different ionic forms, a broad range of ionic phase contents (EW ∼ 859-42 252 g eq-1) and temperatures. The study indicates that the lamellar arrangement of the ionic domains is the most representative morphology that accounts for the physical properties of this ionomer. The lamellar SAXS reflections of Nafion are enhanced in electric and magnetic field-aligned membranes, as confirmed by atomic force microscopy (AFM). Electric and magnetic field-assisted casting of Nafion allowed producing nanostructured and anisotropic films with the lamellas stacked perpendicularly to the field vector, which is the direction of interest for several applications. Such nanostructured Nafion membranes are bestowed with advanced optical and proton transport properties, making them promising materials for solar and fuel cells.

Suppressing vanadium crossover using sulfonated aromatic ion exchange membranes for high performance flow batteries

Novel ion exchange membrane with just the right width of selective aqueous ionic domain (<0.6 nm) and unique functionalities show extraordinary ion selectivity. These unique ion transport properties of our membrane is reflected in a remarkable flow battery performance.

Preparation of acid block anion exchange membrane with quaternary ammonium groups by homogeneous amination for electrodialysis-based acid enrichment

Proton leakage defect of anion exchange membrane (AEM) seriously restricts the applications of electrodialysis (ED) in acid enrichment. Different from conventional scheme in which weak base groups are usually introduced, strong base AEMs are endowed with acid block property by the specific design of membrane microstructure in this work. Firstly, as confirmed by 1H NMR and FTIR, a series of quaternary ammonium polysulfone containing long alkyl side chains pendant are synthesized for AEM preparation. Small Angle X-ray Scattering experiments show that ionic domains form a distinct and well-separated phase. The introduced hydrophobic side chains strengthen the hydrophobic matrix and then restrict AEM water uptake. Besides, some interesting confinement effects are observed, for examples, the reinforcement of Donnan exclusion for H+ and facilitated transport of counter-ions. Furthermore, influences of pendant carbon chain length and ion exchange capacity are investigated. Notably, ED measurements show as-prepared AEMs indeed display excellent acid block performance, a current efficiency of almost 100% under certain condition, which substantially exceeds that of conventional AEM fabricated by heterogeneous aminaiton. This observation demonstrates an unprecedented result that novel strong base AEM with both outstanding acid block performance and membrane conductivity can be achieved by constructing phase separation microstructure.

Fluorocarbon-Based Ionomers with Single Acid and Multiacid Side Chains at Nanothin Interfaces

Unraveling ion conduction limitations in nanothin ionomer films is crucial for designing efficient ionomer–catalyst interfaces and improving redox efficiency in electrochemical devices. This work took a multifaceted approach to understand local proton conduction environments in sub-μm thick films of three fluorocarbon-based ionomers, Nafion, 3M PFSA and 3M PFIA with IEC ∼ 0.91, 1.21, and 1.61 mequiv/g, respectively. After incorporating fluorescent photoacid probe pyranine (HPTS) into films, the extent of proton conduction (Id/Ip), local proton concentration, pH, and ionic domain size (did) were predicted by monitoring the ratio of fluorescence intensity of deprotonated (Id) to that of the protonated (Ip) state of HPTS. Id/Ip decreased with film thickness and followed the trend: 3M PFIA > 3M PFSA > Nafion. A higher water uptake did not necessarily lead to higher Id/Ip indicating that other factors than water uptake control proton conduction under confinement. Size of the ionic domains (did), measured independently using in-plane reflection small-angle X-ray scattering and fluorescence spectroscopy, followed the same trend as Id/Ip. As the RH and film thickness decreased, did became smaller. The close match of did obtained from both techniques supported the reliability of information confered by fluorescence spectroscopy about key controlling parameters of the local proton conduction environment. The highest Id/Ip of 3M PFIA films was attributed to its flexible, multiacidic side chain that helped to form larger ionic domains with better phase segregation. Conversely, smaller, extremely acidic and poorly phase segregated ionic domains with highly confined water molecules led to lower Id/Ip in Nafion films, despite high water uptake.

Effect of Surface Alignment on Connectivity in Phosphonium-Containing Diblock Copolymer Anion-Exchange Membranes

The performance of ion-exchange membranes in fuel cells is critically linked to their ion-conducting morphology. In this report, we analyzed the connectivity of anion-exchange membranes (AEMs) by electrostatic force microscopy (EFM). As a tapping-mode AFM-based technique, EFM probes height, phase, and electrostatic force gradient through two-pass interleave scans, which reveals the direct relationship between membrane surface morphology and connectivity of the ionic domain. The AEMs are diblock copolymers of a polyisoprene (PIp) block and a polystyrenic block containing the phosphonium ion (P(R3P+)MS). Different alignments of cylinders were observed in the bulk and on the surface for AEMs with different ion-exchange capacities (IECs) and preparation methods. The impacts of the cylinder alignment on the connectivity of the ionic domain were then investigated by EFM. For AEM 13 with IEC = 0.44 mmol/g and a hexagonal morphology, cylinders aligned parallel to the surface, which led to many disconnected regions observed throughout the membrane. In contrast, the perpendicularly aligned channels of AEM 16 with IEC = 0.87 mmol/g consisted only of a well-connected ionic phase throughout the membrane.

Novel Sulfonated Aromatic Polymer Membranes for Breaking the Coulombic and Voltage Efficiency Trade-Off Limitation in Vanadium Redox Flow Battery

Vanadium redox flow batteries (VRFBs) have received extensive attention due to its attractive features for the large-scale energy storage because of their design flexibility, absence of intercalation/deintercalation and stress build-up in electrodes, and safe operation. One of the most critical components in VRFB is an ion exchange membrane which can prevent cross mixing of the multivalence vanadium ions, while it still allows the transport of protons (or anions) to complete the circuit. However, the trade-off relationship of proton exchange membrane limits the energy efficiency (EE) of the VRFB due to low coulombic efficiency (CE) caused by vanadium ion cross over through the membrane or high membrane resistances. Anion exchange membrane suffers from poor chemical stability and low voltage efficiency due to low ion conductivity. In this study, we synthesized a series of novel sulfonated aromatic polymer membranes having high proton conductivity as well as selectivity which surpass the proton conductivity-selectivity trade-off relationship. The effect of the pendent group structure on the membrane ion selectivity and battery performance was investigated. It was found that the incorporation of aromatic structures on the pendent groups effectively improved the proton conductivity and selectivity. The membrane with aromatic pendent groups (BPAr-F4) shows 3 times higher vanadium/proton ion selectivity than Nafion 212. As a result, the VRFB single cell equipped with the 80um-thick BPAr-F4 membrane shows significantly better performance in comparison to the cell with Nafion membranes, as high as 97.18% CE, 95.91% VE and 93.20% EE (vs. 75.14% CE, 96.12% VE and 72.22% EE of Nafion 212; 91.30% CE, 95.63% VE and 87.62% EE of Nafion 117) at 20 mA/cm2. Small-angle X-ray scattering (SAXS) studies indicates that their unique morphologies with narrow aqueous ionic domains which are well organized with acidic -SO3H groups results in the high proton selectivity and VRFB performance.

Selective ion transport through hydrated cation and anion exchange membranes I. The effect of specific interactions

Ion partitioning between membranes with fixed ionic groups and aqueous solutions containing different simple salts and acids (LiCl, CsCl, HCl) is studied experimentally for dilute and concentrated solutions and cation and anion exchange membranes including Nafion®, Aquivion®, sulfonated polystyrene, sulfonated polyether ketone, sulfonated poly(phenylene sulfone), poly(acrylic acid) and a poly(phenylene oxide) functionalized with quaternized ammonium groups. For the given membranes and ions, ion partitioning is fully described by the degree of ion pairing which is controlled by specific interactions between counter- and fixed-ions (site-binding), ion hydration and membrane swelling. In the case of cation exchange membranes, specific interaction is highest for the most acidic fixed ionic groups and cations with the highest polarizability and lowest electronegativity (here Cs+). Data on ion partitioning combined with data on ion diffusion (obtained by 7Li, 133Cs NMR) and direct electrochemical transference number measurements show that selective ion uptake does not significantly change counter-ion transference numbers (compared to transference numbers of the corresponding aqueous solution), but it does reduce the total conductivity. Especially for membranes in highly concentrated salt solutions, where Donnan-exclusion does not apply, all ionic transference numbers approach these of the corresponding aqueous solutions. Under these conditions, the transport properties of cation and anion exchange membranes are similar and close to the transport characteristics of simple diaphragms. With appropriate implementation of counter-ion association/dissociation equilibria and ion hydration numbers, the Donnan-equation describes co- and counter-ion partitioning in a quantitative way. Apart from counter-ion/co-ion discrimination in dilute solution, no selective transport of specific ions significantly beyond selectivity characteristics of homogeneous aqueous solutions is expected. For larger ions or other dissolved species within ionomers with narrow aqueous ionic domains, however, there are additional steric effects (ion-sieving) which will be discussed in the second part of this series while the third part will present results of atomistic modelling.

Homogeneous phase crosslinked poly(acrylonitrile-co-2-acrylamido-2-methyl-1-propanesulfonic acid) conetwork cation exchange membranes showing high electrochemical properties and electrodialysis performance

Herein, we report a simple process for the preparation of homogeneous crosslinked conetwork cation exchange membranes (CEMs). The synthesis strategy is based on sequential reaction of hydrazine hydrate and nitrile moieties of random copolymers of poly(acrylonitrile) and poly (2-acrylamido-2-methyl-1-propanesulfonic acid) (PAN-co-PAMPS). Copolymerization of the two monomers enhances miscibility between relatively hydrophobic PAN and hydrophilic ionic PAMPS domains which prevents microphase separation in the membrane matrices. The homogeneous phase co-continuous morphology with no microphase separation in the membrane matrices was confirmed by the homogeneous distribution of color solutes in the membrane matrices as well as by DSC, DMA, TEM, and AFM analyses. Both crosslinked (conetwork) and uncrosslinked copolymers (different composition) acted as CEMs. The CEMs were employed for desalination via electrodialysis. A representative crosslinked CEM (PAN-PAMPS-1) containing 15 mol% PAMPS exhibited the best desalination performance. Crosslinking of the copolymers improves the transport number, desalination performance, and lowers the power consumption of the membranes. This work thus highlights the benefit of crosslinking of ionic random amphiphilic copolymers to obtain CEMs with improved performance during desalination via electrodialysis.

Substrate‐Dependent Molecular and Nanostructural Orientation of Nafion Thin Films

AbstractThe effects of film thickness and substrate composition on the ionomer structure in porous electrodes are critical in understanding pathways toward developing higher performance electrochemical devices, including fuel cells and batteries. Insights are gained into the molecular and nanostructural orientation dependence for thin Nafion films (12–300 nm thick) on gold, platinum, and SiO2 model substrates. Molecular orientation is determined from the birefringence measured using spectroscopic ellipsometry, while the nanostructural orientation of the ionic domains is measured using grazing‐incidence small‐angle X‐ray scattering. Density functional theory calculations for the molecular polarizability of the Nafion backbone and side chain show complimentary contributions to the measured birefringence values for the material. Nafion films prepared on SiO2 substrates exhibit a nearly isotropic molecular and nanostructural orientation. Films on gold and platinum display parallel backbone orientations, relative to the substrate, with decreasing film thickness. However, a birefringence transition toward molecular isotropy is observed for 30 nm thick films on Au and Pt; while the ionic nanostructured domains continuously align parallel to the substrate. This apparent isotropic molecular orientation with increasing domain orientation highlights the difference between the backbone and side chain orientation, a key finding for elucidating transport in confined films at the interfaces.

Design of Ionic Liquid Crystals Forming Normal-Type Bicontinuous Cubic Phases with a 3D Continuous Ion Conductive Pathway

We have prepared a series of pyridinium-based gemini amphiphiles. They exhibit thermotropic liquid–crystalline behavior depending on their alkyl chain lengths and anion species. By adjusting the alkyl chain lengths and selecting suitable anions, we have obtained an ionic amphiphile that exhibits a normal-type bicontinuous cubic phase from 38 °C to 12 °C on cooling from an isotropic phase. In the bicontinuous cubic liquid–crystalline assembly, the pyridinium-based ionic parts align along a gyroid minimal surface forming a 3D continuous ionic domain while their ionophobic alkyl chains form 3D branched nanochannel networks. This ionic compound can form homogeneous mixtures with a lithium salt and the resultant mixtures keep the ability to form normal-type bicontinuous cubic phases. Ion conduction measurements have been performed for the mixtures on cooling. It has been revealed that the formation of the 3D branched ionophobic nanochannels does not disturb the ion conduction behavior in the ionic domain while it results in the conversion of the state of the mixtures from fluidic liquids to quasi-solids, namely highly viscous liquid crystals. Although the ionic conductivity of the mixtures is in the order of 10–7 S cm–1 at 40 °C, which is far lower than the values for practical use, the present material design has a potential to pave the way for developing advanced solid electrolytes consisting of two task-specific nanosegregated domains: One is an ionic liquid nano-domain with a 3D continuity for high ionic conductivity and the other is ionophobic nanochannel network domains for high mechanical strength.

Effect of humidity and temperature on proton conduction in phosphonated copolymers

Phosphonated block copolymers based on poly(vinylbenzyl phosphonic acid) are examined under varied humidity and temperatures for their proton conducting properties. The copolymers have rod-like poly(phenylene oxide) block that induces ordered domains. The ordered and crystalline domains are associated with higher proton conductivity. The highest conductivity approaching 10−2 S/cm was determined under ambient conditions for the copolymer with a rather shorter PPO block. Scanning electron microscopy images of the copolymer reveal interconnected ionic domains that are related directly with the higher conduction in phosphonated block copolymer. A comparative study with sulfonated Nafion suggests that phosphonated polymers too can be used in fuel cell operating at a high temperature range.