Plasticized single-ion polymer conductors: conductivity, local and segmental dynamics, and interaction parameters

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Ionomers are polymers with ionic groups, crucial for applications like batteries and fuel cells.
• Understanding ion transport in plasticized ionomers is key to optimizing their performance.
• Polymer local (beta) and segmental (alpha) dynamics influence ion mobility.

Purpose of the Study:

• To investigate the effect of plasticizers on ion conductivity in PEO-based ionomers.
• To determine the relationship between polymer dynamics and ion transport mechanisms.
• To identify the critical factors governing conductivity in plasticized ionomer systems.

Main Methods:

• Dielectric spectroscopy was employed on neat and plasticized PEO-based ionomers.
• Analysis included conductivity, relaxation times, activation energies, and relaxation strengths.
• Vogel-Fulcher-Tammann (VFT) fitting was used for alpha process parameters.

Main Results:

• Plasticizers significantly enhanced conductivity while maintaining VFT-like behavior, indicating unchanged ion transport mechanisms.
• Polymer local beta and segmental alpha processes were analyzed, yielding characteristic parameters.
• Glass transition temperature (Tg) emerged as the critical factor governing conductivity.

Conclusions:

• Ionomer conductivity is predominantly controlled by the glass transition temperature (Tg), not solvent quality.
• A universal conductivity master curve was developed based on Tg-normalized temperature.
• Plasticizers enhance conductivity by influencing polymer dynamics around Tg, without changing the fundamental ion transport mechanism.