Crosslinked Polynorbornene-Based Anion Exchange Membranes with Perfluorinated Branch Chains

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Anion exchange membranes (AEMs) are crucial for electrochemical applications.
• Developing AEMs with high performance, particularly high ion conductivity and stability, remains a challenge.
• The influence of specific chemical substituents on AEM properties requires further investigation.

Purpose of the Study:

• To investigate the effect of perfluorinated substituents on the properties of novel polynorbornene-based AEMs.
• To develop AEMs with enhanced ion conductivity, mechanical properties, and controlled swelling.
• To explore a new strategy for achieving high AEM performance at low ion content.

Main Methods:

• Synthesis of cross-linked polynorbornene-based AEMs with perfluorinated branch chains via ring-opening metathesis polymerization.
• Subsequent crosslinking reaction and quaternization to form the final AEM structure.
• Characterization of AEM properties including swelling ratio, toughness, water uptake, and hydroxide conductivity.

Main Results:

• The crosslinked AEMs (CFnB) demonstrated a low swelling ratio, high toughness, and high water uptake simultaneously.
• The AEMs achieved a high hydroxide conductivity of 106.9 mS cm⁻¹ at 80 °C.
• High conductivity was observed even at low ion content (IEC < 1.6 meq g⁻¹), attributed to ion gathering and microphase separation.

Conclusions:

• Introducing perfluorinated branch chains is an effective strategy to enhance AEM properties.
• The developed AEMs offer a promising pathway for high-performance applications requiring efficient ion transport.
• This work presents a new approach for designing AEMs with improved ion conductivity and mechanical integrity.