Alleviating the Mechanical and Thermal Degradations of Highly Sulfonated Poly(Ether Ether Ketone) Blocks via Copolymerization with Hydrophobic Unit for Intermediate Humidity Fuel Cells.

Ae Kim,Dong Yoo,Chul Park,Mohanraj Vinothkannan

doi:10.3390/polym10121346

Abstract

In this contribution, sulfonated poly(ether ether ketone) (SPEEK) is inter-connected using a hydrophobic oligomer via poly-condensation reaction to produce SPEEK analogues as PEMs. Prior sulfonation is performed for SPEEK to avoid random sulfonation of multi-block copolymers that may destroy the mechanical toughness of polymer backbone. A greater local density of ionic moieties exist in SPEEK and good thermomechanical properties of hydrophobic unit offer an unique approach to promote the proton conductivity as well as thermomechanical stability of membrane, as verify from AC impedance and TGA. The morphological behavior and phase variation of membranes are explored using FE-SEM and AFM; the triblock (XYX) membranes exhibits a nano-phase separated morphology. Performance of PEFC integrated with blend and block copolymer membranes is determined at 60 °C under 60% RH. As a result, the triblock (XYX) membrane has a high power density than blend (2X1Y) membrane.

Highlights

Polymer electrolyte fuel cells (PEFCs) have efficacy as next-generation energy devices owing to their features of extraordinary energy density from single-step energy conversion and environmental benignity due to low pollutant-emission levels [1,2,3,4]
We show that even chemically inter-connecting sulfonated poly(ether ether ketone) (SPEEK) using a hydrophobic unit can be a better approach; the corresponding proton exchange membrane (PEM) should be a potential candidate for integration into PEFC devices
Triblock copolymers (XYX) had significant signals in the range of 6.9 to 7.9 ppm, which arose from the aromatic protons of SPEEK and the hydrophobic units

Summary

Introduction

Polymer electrolyte fuel cells (PEFCs) have efficacy as next-generation energy devices owing to their features of extraordinary energy density from single-step energy conversion and environmental benignity due to low pollutant-emission levels [1,2,3,4]. The key drawbacks of this membrane, are limited proton conductivity while operating under anhydrous environment, synthesis difficulty, environmental unfriendliness, and high cost [10,11,12]. The two most common methods used to solve these issues are (i) modification of Nafion using other polymers or inorganic compounds and (ii) designing new PEMs that are free of Nafion [13,14,15,16]. The former strategy typically suffers due to incompatibility between different components.

Methods

Results

Conclusion