Surface-initiated ring-opening metathesis polymerization of 5-(perfluorohexyl)norbornene on carbon paper electrodes

Abstract

Hydrophobic coatings on carbon paper electrodes are known to provide effective water management, superior gas transfer, and improved mechanical stability of the paper in fuel cell applications. Here, we describe the surface-initiated ring-opening metathesis polymerization (ROMP) of 5-(perfluorohexyl)norbornene (NBF6) to prepare fluorocarbon-rich films on carbon paper substrates that were pre-treated with O 2 plasma. For our reaction scheme, the growth of the pNBF6 films is dependent on the concentration of hydroxyl groups on the carbon paper substrate. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to determine the required time for O 2 plasma exposure to saturate the surface with hydroxyl-termini. Complete, conformal pNBF6 films were grown on carbon paper electrodes exposed to O 2 plasma for at least 45 s. These films exhibit hydrophobic and oleophobic surface properties and serve as insulative barriers to the diffusion of aqueous ions to the conductive carbon fibers.