Acidity effects of medium fluids on anhydrous proton conductivity of acid-swollen block polymer electrolyte membranes

Abstract

Sulfuric acid-swollen block polymer membranes exhibit anhydrous conductivities of ∼0.1 S cm−1 that is higher than those of phosphoric acid-swollen membranes, whereas temperature dependence of conductivities of the latter is stronger than the former.

Effects of a Nanophase-Separated Structure on Mechanical Properties and Proton Conductivity of Acid-Infiltrated Block Polymer Electrolyte Membranes under Non-Humidification

“…The temperature and humidity were controlled in the benchtop-type environmental chamber SH-242 (ESPEC Corp.) within a temperature range of 20–95 °C below the T g of polystyrene (∼100 °C) at no humidification, where the humidity in the chamber at all temperatures was determined to be close to 0 %RH by the thermohygrometer Testo 645 (Testo SE & Co. KgaA). To estimate the conductivity (σ DC ) by using eq , a bulk resistance ( R ) of the PEMs was evaluated by reading the extrapolated value of the plot on the horizontal axis (nonzero Z ′ intercept in the Nyquist plot ,, ), where Z ′ is the real part of the complex impedance Z = Z ′ – iZ ″ (see also the Nyquist plots of S–P–S/H 2 SO 4 membranes in Figure S5). σ DC = l AR 0.25em …”

“…The degree of polymerization, number-average molecular weight, and composition of the two S−P−S were determined by 1 H NMR spectroscopy with an Ascend 500 MHz (Bruker Corp.). The 43 First, neat S−P−S films were prepared by a solution casting method with pyridine as a solvent, followed by vacuum drying at 50 °C. The neat S−P−S film was immersed into a solution of H 2 SO 4 in methanol.…”

“…The effects of H 2 SO 4 weight fraction in the PEMs are also investigated. The study uses H 2 SO 4 as an infiltrated acid since block polymer-based PEMs infiltrated with H 2 SO 4 are expected to exhibit higher conductivities under non-humidification than block polymer-based PEMs infiltrated with phosphoric acid when the amount of infiltrated acid is the same . It should also be noted that S–P–S triblock copolymers were used instead of S-P diblock copolymers because S–P–S triblock copolymer-based membranes exhibit better mechanical properties than S–P diblock copolymer-based membranes due to formation of polymer network by bridging P center blocks with the hard S domains in the S–P–S triblock copolymer-based membranes …”

“…The effect of the acidity of the specific acid (H 2 SO 4 or phosphoric acid) on the conductivity of the S−P−S/acid membranes was evaluated as well, revealing that H 2 SO 4 was more effective in preparing highly conductive acid-infiltrated PEMs than phosphoric acid. 43 Depending on the composition of block polymers, nanophase-separated structures of block polymers vary from a spherical structure with isolated discontinuous spheres in a continuous matrix to a lamellar structure with stacked continuous layers. 47,48 If nanophase-separated structures formed in PEMs of acid-infiltrated block polymers are different, the PEMs should also exhibit different conductivities and mechanical properties.…”

Sulfonated Block Copolymers: Synthesis, Chemical Modification, Self-Assembly Morphologies, and Recent Applications

“…Conversely, the proton conductivity increased by three orders of magnitude, from 0.0001 to 0.5 S/cm. This behavior was explained in terms of the ease of dissociation of the Sa within the triblock copolymer in the range of low to near room temperatures [ 87 ]. Yan et al induced the formation of gyroid morphologies, by the formation of ionic aggregates, in a series of precisely segmented polyethylene-like materials, containing sulfonate groups (PES23) using different counterions such as Li + , Na + , Cs + , or NBu 4+ .…”