Nonaqueous Interfacial Polymerization-Derived Polyphosphazene Films for Sieving or Blocking Hydrogen Gas

Area of Science:

• Polymer Chemistry
• Materials Science
• Membrane Technology

Background:

• Cyclomatrix polyphosphazenes offer tunable properties for advanced applications.
• Interfacial polymerization (IP) is a versatile technique for creating thin polymer films.
• Controlling polymer network structure is key to achieving desired material properties.

Purpose of the Study:

• To synthesize novel cyclomatrix polyphosphazene films via nonaqueous interfacial polymerization.
• To investigate the effect of potassium hydroxide concentration on film structure and properties.
• To evaluate the gas barrier and gas separation performance of the prepared films.

Main Methods:

• Nonaqueous interfacial polymerization (IP) using aromatic hydroxyl compounds and hexachlorocyclotriphosphazene.
• Preparation of polymer films on ceramic supports.
• Tuning deprotonation extent via potassium hydroxide concentration.
• Gas permeation experiments to assess barrier and permselective properties.

Main Results:

• Films exhibited tunable properties, ranging from hydrogen/oxygen barriers to high-temperature hydrogen-selective membranes.
• High potassium hydroxide concentration yielded barrier films with very low H2 and O2 permeabilities.
• Lower potassium hydroxide concentrations resulted in molecular sieving behavior with high H2/N2, H2/CH4, and H2/CO2 permselectivities at 200 °C.

Conclusions:

• The interfacial polymerization method allows for precise control over cyclomatrix polyphosphazene film properties.
• These tunable polymer films show significant potential for gas separation and barrier applications.
• The developed materials demonstrate excellent performance, particularly for high-temperature hydrogen separation.