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

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.

Influence of thermal history on the mechanical properties of poly(ether ketone ketone) copolymers

“…In a previous article, we showed that for high temperature and time exposure, PEKK 6002 undergoes macromolecular modifications due to crosslinking/branching mechanisms that lead to a decrease in the final crystallinity and crystallization kinetics. This is consistent with the results of Chan et al for PEEK, where crosslinking during heat aging leads to a decrease in crystallization rates. In this part, we assessed the impact of macromolecular modifications at high temperature exposure on PEKK 6002 mechanical properties.…”

Ameliorated Performance of Sulfonated Poly(Arylene Ether Sulfone) Block Copolymers with Increased Hydrophilic Oligomer Ratio in Proton-Exchange Membrane Fuel Cells Operating at 80% Relative Humidity

“…We tested the membrane’s proton conductivity using alternating current (AC) impedance spectroscopy by integrating approximately 3 cm × 0.5 cm membranes into the four-probe BekkTech cell and measuring conductivity at 40, 50, 60, 70, 80 and 90 °C in 80% RH. We calculated conductivity using Equation (3) [ 23 ]. where σ is cation conductivity, L is the length (cm) between the measuring electrodes, R is resistance (Ω), W is film width (cm) and T is film thickness (cm).…”

Amelioration in physicochemical properties and single cell performance of sulfonated poly(ether ether ketone) block copolymer composite membrane using sulfonated carbon nanotubes for intermediate humidity fuel cells

“…This block copolymerization has been more effective than the conventional hydrocarbon membranes, physically blended membranes, and random copolymers owing to their continuous microphase-separated morphology, and improved thermal, mechanical, and electrochemical properties. 18,19 Highlights • An organic-inorganic hybrid membrane was exploited for intermediate humidity fuel cell applications. • Sulfonated CNTs improved the water retention and other physicochemical properties of composite membranes.…”

“…The hydrophilic segments provide the broad interconnected hydrophilic networks responsible for the increased proton conductivity while the hydrophobic segments prevent the excessive swelling of membranes, thereby maximizing their overall performances. This block copolymerization has been more effective than the conventional hydrocarbon membranes, physically blended membranes, and random copolymers owing to their continuous microphase‐separated morphology, and improved thermal, mechanical, and electrochemical properties …”