Hydrogen bonding and charge transport in a protic polymerized ionic liquid.

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Protic polymerized ionic liquids (PPILs) are promising electrolytes.
• Understanding charge transport mechanisms is crucial for their application.
• Hydrogen bonding significantly influences polymer properties.

Purpose of the Study:

• To investigate the interplay between hydrogen bonding and charge transport in PAAPS.
• To elucidate the dominant mechanism of charge conduction in PPILs.
• To correlate structural changes with electrical properties over a wide temperature range.

Main Methods:

• Fourier Transform Infrared (FTIR) spectroscopy to analyze hydrogen bond formation and vibrational states.
• Broadband Dielectric Spectroscopy (BDS) to measure complex conductivity from 10⁻² to 10⁹ Hz.
• Combined analysis of FTIR and BDS data across a temperature range of 170–300 K.

Main Results:

• A pronounced thermal hysteresis was observed in the hydrogen bond network formation of PAAPS.
• The effective conductivity, measured by BDS, exhibited reversible behavior with temperature changes.
• Integrated absorbance of N-H stretching vibration changed only by a factor of 4, while conductivity varied by orders of magnitude.

Conclusions:

• Charge transport in PAAPS is predominantly governed by hopping conduction assisted by dynamic glass transitions.
• The establishment of hydrogen bonds has a limited impact on the overall charge transport mechanism.
• The observed hysteresis in H-bond formation suggests a non-equilibrium process distinct from the reversible conductivity.