Synthesis of Multifunctional Hyperbranched Polymers via Atom Transfer Radical Self-Condensing Vinyl Polymerization...

Area of Science:

• Electrochemistry
• Polymer Science
• Materials Science

Background:

• Anion exchange membranes (AEMs) are critical for electrochemical energy devices, facilitating non-precious metal catalysis in alkaline conditions.
• Challenges include alkaline degradation, necessitating improved membrane stability and ion transport.
• Hyperbranched polymers (hbPs) offer a promising solution due to their unique structure and synthesis.

Purpose of the Study:

• To synthesize and characterize multifunctional hbPs for polyurethane-based AEMs.
• To investigate the impact of hbP architecture on AEM performance, including alkaline stability, ion conductivity, and water uptake.
• To develop a tunable strategy for high-performance AEMs.

Main Methods:

• Synthesis of multifunctional hbPs via atom transfer radical self-condensing vinyl polymerization (ATR-SCVP) using 4-vinylbenzyl chloride (VBC) and 2-hydroxyethyl methacrylate (HEMA).
• Crosslinking of hbPs into polyurethane-based AEMs.
• Characterization of membrane properties: alkaline stability, water uptake, ion-exchange capacity (IEC), and hydroxide conductivity (OH^- conductivity).

Main Results:

• Successful synthesis and crosslinking of hbPs into AEMs with excellent alkaline stability.
• Membranes with higher molecular weight and VBC-richer hbPs showed high water uptake but limited conductivity.
• Optimized hbP architecture (OH-hbP2-PU) yielded the highest OH^- conductivity (338 µS/cm) and IEC (2.64 mmol/g).

Conclusions:

• Tailored hbP architecture is crucial for balancing water uptake and ion transport in AEMs.
• The developed hbP-based AEMs demonstrate potential for high-performance electrochemical energy devices.
• This study provides a tunable strategy for designing advanced AEMs through controlled hbP synthesis.