Preparation of Poly(phenylene oxide-gstyrenesulfonic acid) and their Characterization for DMFC Membrane

Abstract

Well-defined poly(2,6-dimethyl-4,4 1 -phenylene oxide)-g-poly(styrenesulfonic acid) (PPO-g-PSSA) graft copolymer was synthesized via living radical polymerization. For the graft copolymer, poly(2,6-dimethylphenylene oxide) (PPO) was brominated first, and the brominated PPO (PPO-Br) was used as a macroinitiator in the atom transfer radical polymerization (ATRP) of styrenesulfonic acid sodium salt. The number of grafts per PPO chain and the molecular weight of the graft were controlled by adjusting the degree of bromination, and conversion in ATRP, respectively. The graft copolymers obtained were transformed into proton exchange membranes for direct methanol fuel cell (DMFC) application. The performance of the membranes was measured in terms of water uptake, proton conductivity, methanol permeability, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with PSSA block content. Very low methanol permeability and good proton conductivity were observed by adjusting grafting frequency and PSSA block content.

Preparation of sulfonated crosslinked poly(2,6‐dimethyl‐1,4‐phenylene oxide) membranes for direct methanol fuel cells by using electron beam irradiation

“…However, the two major weight losses were observed in the SCPPO at 200 and 430 °C. These decompositions are caused by the desulfonation of sulfonic acid groups and the degradation of the PPO main chain, respectively 25, 26…”

The application of covalently cross-linked BrPPO as AEM in alkaline DMFC

“…Several groups performed reactions with bromine and they got bromination of the side chain and the arylene backbone [31][32][33]. Applying different reaction conditions, the relation of side chain bromination and backbone bromination can be influenced [34].…”

Proton exchange composite membranes from blends of brominated and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)

“…The former was approved by our previous study, in which the membrane directly sulfonated from BPPO (not BPPO/SPPPO blends) showed extremely low methanol permeability, especially at the case of low sulfonation degrees 35. The latter was confirmed by the job of Cho et al It was reported that membranes prepared from a brominated poly(2,6‐dimethyl‐1,4‐phenylene oxide)‐ g ‐poly(styrenesulfonic acid) (PPO‐ g ‐PSSA) graft copolymer had very low methanol permeability, with a magnitude of 10 −7 cm 2 s −1 , and this value decreased with an increase in BPPO graft 36. Though in this case, brominated PPO is used as a macro‐initiator for grafting sodium styrene sulfonated on to PPO via living free radical polymerization and increasing BPPO results in greater graft content but the resulting polymer would not contain appreciable amounts of bromine.…”