Transport Properties of Sulfonated Poly(styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities

Abstract

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Ion transport in sulfonated polymers

“…20,30,47 The uniqueness of these materials can be attributed to the fact that they can self-assemble into ordered periodic microstructures, [29][30][31][32]37,65 which offers the potential of gaining an extremely valuable insight into the effects of nanoscale morphology on proton transport. In these systems, the structural aspects, such as the types of self-assembled structures, the width of the hydrophilic phases, and the orientation of the water channels located within the hydrophilic domains become highly relevant parameters for understanding the transport properties of PEMs.…”

“…It has been widely reported that the phase-separated hydrophobic phases can provide effective mechanical support while the well-arranged nanometer-scale hydrophilic domains facilitate ion transport by means of confinement effects (at the same ion exchange capacity (IEC) value, ions confined within microphase-separated hydrophilic phases are in close proximity, compared to their random analogues). 8,10,28,29 Examples of such polymers include sulfonated poly(styrene-b-isobutylene-b-styrene), 30,31 sulfonated poly(styrene-b-methylbutylene), 28,32 sulfonated poly(ether ether ketone)-b-poly(ether sulfone), 33,34 and sulfonated poly([vinylidene difluoride-chlorotrifluoro ethylene]-gstyrene). 19,35,36 Note in passing that although much of the research on the sulfonated polymers indicated that morphology is important in determining transport properties, the achievement of well-defined structures with long-range order is lacking and it has been the subject of the current studies.…”

“…32,37 In addition, as it has become clear that the transport properties can be improved by controlling the self-assembled morphologies of sulfonated block/graft copolymers, the need for understanding thermodynamic properties of sulfonated PEMs has increased. 30,32,37 Very recently, as part of an effort to enhance the performance of PEMFCs, studies on sulfonated PEMs entered a new phase, aiming at PEMFC operation under anhydrous conditions. This tide was triggered by the requirement for high operation temperatures exceeding 120 C in order to minimize CO poisoning at the surface of the Pt catalyst and to improve the transport efficiency in PEMFC systems.…”

Transport and Electro‐Optical Properties in Polymeric Self‐Assembled Systems

“…The conductivity is comparable to that of Nafion and the methanol permeability is strongly reduced [189]. A systematic study dealing the correlation between the structure and conductivity was recently reported using sulfonated SIBS [195,201] using a range of degrees of sulfonations and different solvents to cast the membranes. Well-defined cylindrical and lamellar self-assembled ion channels could be obtained but typically they are parallel to membrane surfaces, leading to reduced conductivity across the mem- Fig.…”

“…3.5 Sulfonated polystyrene-b-polyisobutene-b-polystyrene leads to well defined self-assembled structures at low levels of sulfonation and the domains are aligned parallel to the membrane. Increasing the sulfonation level leads to less periodic structures but also to increased proton transport [201].…”