Thermally triggered polyrotaxane translational motion helps proton transfer

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Developing efficient proton-conducting membranes is crucial for energy technologies like fuel cells and redox flow batteries.
• Synthetic polyelectrolytes offer potential but face challenges in achieving high proton transport rates.

Purpose of the Study:

• To engineer a novel polymer entity using rotaxane structures for enhanced proton transport.
• To investigate the role of thermally triggered molecular motion in facilitating proton transfer.

Main Methods:

• Assembly of a rotaxane-based polymer via host-guest interactions.
• Utilizing the thermally induced translational motion of the rotaxane's mechanically bonded components.
• Measuring proton conductivity at approximately 60°C.

Main Results:

• Achieved a proton conductivity of 260.2 mS cm⁻¹, surpassing state-of-the-art Nafion.
• Demonstrated this high conductivity at a low ion-exchange capacity of 0.73 mmol g⁻¹.
• Observed proton transfer enhancement linked to the relative motion of the sulfonated axle and ring.

Conclusions:

• Rotaxane-based polymers can achieve exceptionally fast proton transfer through thermally activated molecular motion.
• This approach offers a promising strategy for designing advanced proton-exchange membranes.
• The findings pave the way for improved materials in fuel cells and batteries.