Additive-Free Ionic Polyurethanes with Ultrasensitive Thermo-Switchable Conductivity and Melting Stability.

Area of Science:

• Materials Science
• Polymer Chemistry
• Condensed Matter Physics

Background:

• Thermally switchable ion-conductive polymers (TSIPs) are promising for flexible electronics and information encryption.
• Existing TSIPs face challenges including ion leaching, interfacial instability, and poor temperature sensitivity.

Purpose of the Study:

• To develop novel ionic polyurethanes with enhanced temperature-switchable conductivity and reduced limitations.
• To investigate the ion transport mechanisms and material properties for advanced applications.

Main Methods:

• Synthesized ionic polyurethanes with covalently grafted ionic groups.
• Characterized thermo-electrical response and temperature coefficient of conductivity.
• Employed modeling of electrode polarization to elucidate ion transport mechanisms.
• Evaluated photoluminescence and optical transition properties.

Main Results:

• Achieved ultra-sensitive thermo-electrical response with a record-high temperature coefficient of conductivity (30.2%°C^-1).
• Identified a dual ion transport mechanism involving segmental motion and ionic cluster reconstruction.
• Demonstrated stable photoluminescence and reversible opaque-to-transparent transitions.
• Confirmed mechanical integrity in the melt state due to dynamic reorganization of ionic clusters.

Conclusions:

• The developed ionic polyurethanes offer a versatile platform for flexible electronics and multimodal anti-counterfeiting.
• Covalent grafting of ionic groups and control over soft segment length enable precise conductivity switching.
• The materials exhibit unique properties for advanced applications requiring thermal responsiveness and security features.