Novel multiblock‐co‐ionomers as potential polymer electrolyte membrane materials

Abstract

In this contribution a series of novel multiblock‐co‐ionomers consisting of hydrophobic (partially fluorinated) and hydrophilic (sulfonated) domains has been prepared and characterised in terms of their applicability as fuel cell membranes. The synthesis of these multiblock‐co‐ionomers is a four‐step procedure including (1) the sulfonation of the monomer 4,4′‐difluorodiphenylsulfone, (2) the preparation of hydrophilic telechelic macromonomers by molecular‐weight controlled step‐growth polycondensation of the sulfonated monomer with various bis(thio)phenols, (3) the preparation of a hydrophobic telechelic macromonomer and (4) the coupling of both telechelic macromonomers to yield microphase‐separated block‐co‐ionomers. This study focuses on the investigation of the influence of various linkage groups and atoms within the hydrophilic domains of the multiblock‐co‐ionomers. Both the telechelic macromonomers and the multiblock‐co‐ionomers were structurally investigated by 1H‐ and 19F‐NMR spectroscopy and gel permeation chromatography (GPC). All multiblock‐co‐ionomers of this series could be cast into membranes and their membrane properties (ion‐exchange capacity, specific resistance, swelling ratio, water uptake, thermal and oxidative stability) were measured and discussed in dependence of the various linkage groups within the hydrophilic domains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5237–5255, 2007

Partially Fluorinated Arylene Polyethers and Their Ternary Blend Membranes with PBI and H3PO4. Part I. Synthesis and Characterisation of Polymers and Binary Blend Membranes

“…The degree of polymerisation (DP) for the stepgrowth polymerisation of decafluorobiphenyl and bisphenol AF can be adjusted by the stoichiometric imbalance r of the two monomers according to Carother's Eq. (1) [34][35][36].…”

Synthesis of partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions

“…To further improve the proton‐conducting properties, block copolymer structures were recently regarded as promising. Accordingly, hydrophilic/hydrophobic multiblock copolymers have been investigated for PEM materials because of their ability to form hydrophilic−hydrophobic phase‐separated morphology with interconnected ionic channels. Mikami et al reported recently on perfluoroalkyle sulfonic acid‐modified poly(arylene ether) ionomer membranes and found that the block copolymer structure has an effective impact in improving the proton‐conducting behavior without increasing the ion exchange capacity.…”

Highly Sulphonated Multiblock‐co‐polymers for Direct Methanol Fuel Cells

“…As the block lengths of the hydrophilic and hydrophobic oligomers influence the IEC, end-group analysis using NMR-spectroscopy was applied to reveal deviations between theoretically calculated and experimentally obtained block lengths. The hydrophilic block length (n) was investigated with 1 H-NMR and the hydrophobic block length (m) with 19 F-NMR [26].…”

“…The polymer electrolyte membrane (PEM) is the key component of the system and transfers protons from the anode to the cathode. Requirements on PEMs are good proton conductivity, zero electronic conductivity, good mechanical properties in the dry and hydrated state, high oxidative and thermal stability, low-fuel permeability, low water and methanol transport through diffusion and electro-osmosis as well as economically reasonable production and maintenance costs [1,2]. The current state-ofthe-art PEM materials are polyperfluoroalkylsulphonic acids such as Nafion ® , Flemion ® and Aquivion ® [3].…”

“…Moreover, their high-production costs and non-environmental friendly, complicated production processes have to be overcome. During the last decades much effort has been done to develop alternative PEM materials with comparable or superior properties [1][2][3][6][7][8]. One relatively new approach in designing novel membrane materials is the synthesis of nanophase-separated multiblock-co-polymers, consisting of sulphonated hydrophilic and hydrophobic blocks.…”