Self-assembled highly ordered acid layers in precisely sulfonated polyethylene produce efficient proton transport.

Area of Science:

• Polymer Chemistry
• Materials Science
• Electrochemistry

Background:

• Advances in polymer synthesis enable precise control over polymer chain structure.
• Sulfonated polymers are crucial for ion-exchange membranes in applications like fuel cells.
• Existing materials like Nafion 117 set a high standard for proton conductivity.

Purpose of the Study:

• To engineer controlled chain folding in sulfonated polyethylene.
• To achieve high proton conductivity through a crystalline polymer structure.
• To explore novel polymer membrane designs for efficient ion transport.

Main Methods:

• Synthesis of linear polyethylene with precisely placed sulfonic acid groups.
• Inducing controlled hairpin chain folding via functionalization.
• Characterization of hydrated layer formation and proton conductivity measurements.

Main Results:

• Creation of highly uniform, subnanometre-thick hydrated acid layers.
• Achieved proton conductivity comparable to Nafion 117.
• Demonstrated hairpin chain folding within a crystalline polymer matrix for ion conduction.

Conclusions:

• Well-controlled chain folding is a viable strategy for proton conductivity in crystalline polymers.
• This polyethylene-based structure offers a new paradigm for functional polymer membranes.
• The design is adaptable for selective transport of various ions and small molecules.