Polybenzimidazole (PBI) is a high-performance polymer having high thermal stability, chemical resistance, and mechanical strength making it suitable for many applications, such as, in the aerospace industry, and in high temperature proton exchange membrane fuel cells (HT-PEMFCs) where the PBI film is doped with phosphoric acid (H3PO4) to promote proton transfer via hydrogen bonding between phosphoric acid and the nitrogen-containing groups in PBI. This research investigated oxidation of the PBI surface using 253.7 and 184.9 nm UV photo-oxidation in the presence of an atmospheric pressure of oxygen. Ozone is formed by the photo-dissociation of oxygen involving the 184.9 nm photons while the 254.7 nm photons are transmitted through oxygen and photo-absorbed by the PBI surface. Surface modification was characterized, as a function of treatment time, using X-ray photoelectron spectroscopy (XPS), water contact angle (CA), and Atomic Force Microscopy (AFM) measurements to determine changes in chemistry, hydrophilicity, and surface roughness, respectively. Thermal Gravimetric Analysis (TGA) was used to monitor the increase in retention of phosphoric acid to the modified PBI surface.

Surface modification of polybenzimidazole (PBI) with ozone and UV photo-oxidation

ACS Fall 2020 Virtual Meeting

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