Charge transfer interactions between polyaniline and surface functionalized polymer substrates

The surfaces of conventional polymer films, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), poly(ethylene terephthalene) (PET) and polytetrafluoroethylene (PTFE) were functionalized via graft copolymerization with acrylic acid (AAc) and Na salt of styrenesulfonic acid (NaSS). The as-functionalized polymer surfaces can thus be rendered conductive, through interfacial protonation, when coated with neutral emeraldine (EM) base. The physicochemical properties at the interfaces, such as compositions and protonation levels, were evaluated by X-ray photoelectron spectroscopic (XPS) technique. Other substrate surface functionalization techniques, such as sulfonation (for LDPE, HDPE, PET and PP) and hydrolysis (for PET) were also explored. It was found that in the presence of surface grafted or covalently bonded -SO3− groups, protonation level in the order of 50% can be readily achieved in the coated EM layer.