Single-walled carbon nanotube modification on photograft-polymerized nation films via covalent and ionic bonding

Acrylic acid (AAc) and diallyldimethylammonium chloride (DADMAc) were photograft-polymerized onto the surfaces of perfluorosulfonic acid (Nafion) membranes using 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamide (ACMP) or Mohr's salt as a polymerization initiator. The degree of photografting changed from 1 wt% to 13.7 wt% depending on the experimental conditions (monomer, initiator and UV-light irradiation time). Shortened single-walled carbon nanotubes (s-SWNTs) prepared by a mixed acid treatment were immobilized in the grafted Nafion films by two different methods (methods A and B). Method A is a covalent-modification of the s-SWNTs with an acrylic acid (AAc)-photografted Nafion membrane in the presence of a diamine and a condensation reagent. Method B uses ion-complexation between the s-SWNTs with an anionic charge and a DADMAc-photografted Nafion film with a cationic charge. Based on the characterization of the hybrid materials by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), it was found the s-SWNTs were immobilized into the photografted-Nafion films by both methods.