Efficient Sulfonation of Syndiotactic Polystyrene Membranes Assessed by Small-Angle Neutron Scattering

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Syndiotactic polystyrene (sPS) exhibits selectivity towards small organic molecules, enabling functionalization.
• Sulfonated sPS (s-sPS) is hydrophilic with high proton conductivity, comparable to Nafion.
• s-sPS is a potential hydrocarbon alternative to fluorinated compounds in energy conversion.

Purpose of the Study:

• To evaluate the efficiency of sulfonation across the entire volume of sPS membranes.
• To investigate the structural impact of sulfonation on sPS membranes.
• To assess s-sPS as a material for proton-exchange membranes.

Main Methods:

• Homogeneous functionalization of sPS membranes via sulfonation using lauroyl sulfate in chloroform.
• Small-angle neutron scattering (SANS) analysis on dry and hydrated sPS membranes.
• In-beam hydration with H2O or D2O to highlight structural details using neutron scattering contrast variation.

Main Results:

• Sulfonation was found to be homogeneous within the amorphous phase of the sPS membranes.
• Crystalline regions of the sPS membranes remained unaffected by the sulfonation process.
• The study provides semiquantitative analysis of sulfonation efficiency based on SANS data.

Conclusions:

• Sulfonation of sPS membranes primarily occurs in the amorphous regions.
• s-sPS membranes demonstrate potential for energy applications due to their proton conductivity.
• The findings support the development of s-sPS as a viable alternative to fluorinated proton-exchange materials.