Proton exchange fuel cells (PEFCs) have the potential to provide power for a variety of applications ranging from electronic devices to transportation vehicles. A major challenge towards economically viable PEFCs is finding an electrolyte that is both durable and easily passes protons. In this article, we study novel anhydrous proton-conducting membranes, formed by incorporating ionic liquids into synthetic block co-polymer electrolytes, poly(styrenesulphonate-b-methylbutylene) (s n mB m ), as high-temperature PEFCs. The resulting membranes are transparent, flexible and thermally stable up to 180 °C. The increases in the sulphonation level of s n mB m co-polymers (proton supplier) and the concentration of the ionic liquid (proton mediator) produce an overall increase in conductivity. morphology effects were studied by X-ray scattering and electron microscopy. Compared with membranes having discrete ionic domains (including nafion 117), the nanostructured membranes revealed over an order of magnitude increase in conductivity with the highest conductivity of 0.045 s cm − 1 obtained at 165 °C.

We have investigated morphologies and conductivities of ionic liquids (ILs) incorporated poly(styrenesulfonate-b-methylbutylene) (PSS-b-PMB) block copolymers by varying kinds of heterocyclic diazoles in ILs. A low molecular weight PSS-b-PMB copolymer (3.5–3.1 kg/mol) with sulfonation level of 17 mol % was employed as a matrix polymer, which indicates disordered morphology at entire temperature examined. The addition of different ILs results in the emergence of various ordered morphologies such as lamellar, hexagonal cylinder, and gyroid structures. Interestingly, it has been revealed that ring structures and alkyl substituents in diazoles play an important role in determining the morphologies of ILs impregnated PSS-b-PMB copolymers, attributed to the dissimilar strength of ionic interaction. Heating the ILs doped PSS-b-PMB copolymers causes intriguing thermoreversible order–order and order–disorder phase transitions, which can be rationalized by classical block copolymer thermodynamics. From conductivity measurements, it has been found that the enhanced conductivity could be achieved by increasing number of protic sites in heterocyclic diazoles. Upon exploring morphology effects on conductivities of ILs-containing PSS-b-PMB copolymers, with decoupled segmental motion of polymer chains and ion transport, similar morphology factor of 0.4 has determined if the morphologies are appeared to be lamellar and/or hexagonal cylinder structures. In contrast, the gyroid-forming sample revealed apparently high morphology factor in the range of 0.6 to 0.7, which is intimately related to better connectivity of ionic channels along cocontinuous PSS phases.

We report a new class of polymer electrolytes that exhibit high Li + -ionic conductivity and thermal stability up to 200 °C. The polymer electrolyte consists of a solvate ionic liquid ([Li(G4)][TFSA]), comprising an equimolar mixture of lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) and tetraglyme (G4), and a well-defined ABA-triblock copolymer, polystyrene-b-poly(methyl methacrylate)-b-polystyrene (PStb-PMMA-b-PSt, SMS). The electrolyte is formed by the selfassembly of SMS, where the solvatophobic PSt segments serves as physical cross-linking points, and the solvatophilic PMMA segment with preferentially dissolved [Li(G4)][TFSA] forms ion-conduction paths. In the electrolyte, the preservation of the complex cation [Li(G4)] + in the PMMA phase was demonstrated by pulsed-field gradient spin−echo (PGSE) NMR, Raman spectra, and thermogravimetric analysis. Because of the preservation of [Li(G4)] + , which hinders the direct interaction of Li + with the polymer segment and the coupling of the ionic transport from the segmental motion, the room temperature ionic conductivity of the electrolyte reached an appreciable level (10 −4 −10 −3 S cm −1 ).

We have explored the link between morphologies and conductivities for ionic liquids (ILs) incorporated block copolymer electrolytes by combining small-angle X-ray scattering, transmission electron microscopy, and impedance spectroscopy. The block copolymer electrolytes investigated in present study are a series of partially sulfonated poly(styrenesulfonate-b-methylbutylene) (S n MB m ) copolymers with different molecular weights and sulfonation levels (SLs). Imidazolium-based ILs are selectively doped into hydrophilic domains of S n MB m copolymers, and various morphologies have been observed as a function of the amount of absorbed ILs and SLs in S n MB m copolymers. We have demonstrated that the morphologies of ILs impregnated S n MB m copolymers are sensitive function of kinds of counteranions in IL, yielding remarkable discrepancy in conductivities. When the morphology of sample is appeared to be a lamellar structure, significant reduction in through-plane conductivity value was detected due to the nonrandom orientation of microdomains. In contrast, hexagonally perforated lamellar forming samples exhibit the highest conductivities in both through-plane and in-plane directions on account of the better connectivity of ionic domains along the perforated hydrophilic phases. Once the morphology effects were vanished by employing highly sulfonated S n MB m copolymers, it has been revealed that the conductivities of ILs incorporated copolymers are closely related to the polarity of ILs as confirmed by solvation dynamics study.

We report the synthesis of a series of block copolymers tailored with phosphonic acid groups, poly­(styrene phosphonate-b-methylbutylene) (PSP-b-PMB), which show systematic phase sequences of a disorder, lamellae, and hexagonal cylinder morphology, with controlled acid concentration. These observations were combined with the Leibler theory in order to estimate the effective Flory–Huggins interaction parameter of PSP-b-PMB, χPSP–PMB. For example, χPSP–PMB = 0.101 + 13.823/T was anticipated for the disordered phases observed at the low phosphonation level of 15 mol %. The direct comparison of PSP-b-PMB block copolymers and their sulfonated analogues, poly­(styrene­sulfonate-b-methylbutylene) (PSS-b-PMB), revealed a remarkably similar phase behavior. In-depth thermodynamic studies suggested similar χ values regardless of the kind of acid group when the concentration is lower than 20 mol %, whereas these values vary by increasing the amount of acid groups, as polymers carrying phosphonic acid groups showed a weaker segregation strength. In order to provide insights into the design of acid-bearing polymers as advanced polymer electrolytes, their ion transport properties were investigated upon the addition of various ionic liquids (ILs). The introduction of alkyl substituents in the IL cations was found to be advantageous to improve the conductivity of IL-containing PSP-b-PMB membranes by inducing favorable thermodynamic interactions of the ILs with the polymer matrix, unlike the results observed for IL-containing sulfonated samples. These polymers have the potential to be alternatives to the widely studied sulfonated polymers.