Blocky Ionomers via Sulfonation of Poly(ether ether ketone) in the Semicrystalline Gel State

Abstract

Blocky sulfonated poly(ether ether ketone) (SPEEK) ionomers were synthesized by postpolymerization functionalization in the gel state. Matched sets of blocky and random SPEEK with ion contents between 3 and 11 mol % were prepared, and the thermal transitions and crystallization kinetics were examined using differential scanning calorimetry (DSC). At similar ion contents, the blocky SPEEK exhibited higher crystallizability and faster crystallization kinetics than random SPEEK. Reduced scattering contrast in the USAXS/ SAXS/WAXD analysis of the blocky SPEEK copolymer membranes, relative to the random analogues, suggested that the ionic aggregates in blocky SPEEK were distributed in close proximity to the crystalline domains. Despite similar water uptake values for the low ion content random and blocky SPEEK membranes, the blocky SPEEK exhibited higher proton conductivities than their random analogues. At significantly higher ion contents (45 mol %), the blocky SPEEK membranes remained semicrystalline, showed controlled water uptake, and exhibited a 2.5 times higher conductivity over that of the amorphous, random analogues. Moreover, these new blocky, semicrystalline SPEEK membranes were found to exhibit a proton conductivity that was comparable to that of the benchmark 1100 EW Nafion.

Effect of Chemical Structure and Degree of Branching on the Stability of Proton Exchange Membranes Based on Sulfonated Polynaphthylimides

“…However, perfluorosulfonic acid membranes have some drawbacks, such as high cost, high fuel crossover, low operation temperature, and big deformation under fuel cell operation [13,14]. Over the past few decades, hundreds of low-cost sulfonated polymers, such as sulfonated polyether-ether-ketone [15][16][17][18][19][20], sulfonated polyether sulfone [21][22][23][24][25][26][27][28][29][30][31], and sulfonated polynaphthylimides with different chemical structures, have been synthesized for PEMFCs applications [28,29,32]. Among them, sulfonated polynaphthylimides (SPIs) have attracted considerable attention because of their low cost, excellent physical properties, high methanol gas barrier ability, high thermal stability, and easy-to-adjust chemical structure [33][34][35][36].…”

Butyralization of poly(vinyl alcohol) under supercritical carbon dioxide for a humidity-resistant adhesive to glass substrates

“…The swollen state modification of conventional crystalline polymers have been reported by Moore and co-workers. [35][36][37][38] In the case of syndiotactic polystyrene and poly(ether ether ketone), after modification in swollen states, some parts of crystallite regions were remained. In contrast, the acetalization of PVA with butyl aldehyde in swollen state disappeared their crystalline structure.…”

C−H Functionalization of Commodity Polymers

“…Most CÀHfunctionalizations of polymers occur randomly along the polymer backbone and result in ag lobal change in properties.P ost-translational modifications (PTMs) of proteins,conversely,are site-selective modifications that increase the functional diversity of biomacromolecules. [177] Developing methods for site-selective post-polymerization modification is an ambitious objective that could drastically increase the functional diversity of commodity polymeric materials.A recent approach toward the precision CÀHf unctionalization of polymers was reported by Moore and co-workers.T he group took advantage of the difference in the mass transport of reagents into the amorphous and crystalline domains of syndiotactic polystyrene and PEEK to realize "blocky" polymer sulfonation (Figure 13 B). [67,178] Theb lock-type,s ulfonated polymer demonstrated distinct properties from its randomly sulfonated analogue,i ncluding af aster rate of recrystallization upon cooling from the melt.…”

“…Most C−H functionalizations of polymers occur randomly along the polymer backbone and result in a global change in properties. Post‐translational modifications (PTMs) of proteins, conversely, are site‐selective modifications that increase the functional diversity of biomacromolecules . Developing methods for site‐selective post‐polymerization modification is an ambitious objective that could drastically increase the functional diversity of commodity polymeric materials.…”