Tuning Polyolefin Hydrophilicity to Control Sulfonation Cross-Linking Kinetics for Carbon Synthesis

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Polyolefins are cost-effective carbon precursors with upcycling potential.
• Sulfuric acid-mediated sulfonation enables crosslinking for carbon conversion via pyrolysis.
• Hydrophobicity of polyolefins hinders acid diffusion, slowing the sulfonation reaction.

Purpose of the Study:

• To investigate enhancing polyolefin hydrophilicity to improve sulfonation kinetics.
• To demonstrate the effectiveness of hydroxyl group grafting for accelerating the reaction.

Main Methods:

• Grafting hydroxyl groups onto a polyolefin backbone (hydrogenated polybutadiene, hPB).
• Comparing sulfonation kinetics and carbon yield of hydroxyl-functionalized hPB versus unmodified hPB.
• Pyrolysis of crosslinked polyolefins to determine carbon yield.

Main Results:

• Hydroxyl functionalization significantly enhanced sulfonation efficiency.
• Hydroxyl-functionalized hPB achieved over 50 wt% carbon yield after only 2 hours of crosslinking.
• Unmodified hPB required 16 hours of crosslinking for a comparable carbon yield.

Conclusions:

• Improving polyolefin hydrophilicity is crucial for overcoming diffusion limitations.
• Accelerated sulfonation kinetics lead to higher carbon conversion efficiency.
• Tailored polyolefin precursor design advances their application in carbon material production.