Surface studies of pristine and surface-modified polypyrrole films

Abstract

SYNOPSISPolypyrrole (PPY) films having high conductivity were synthesized electrochemically in acetonitrile at low temperature and low current density. Pristine, deprotonated, and ozonepretreated PPY films were subjected to either thermally induced or near-UV-light-induced graft copolymerization with acrylic acid (AAc), or sodium salt of 4-styrenesulfonic acid (NaSS). Surface structures and redox states of the pristine, deprotonated, reprotonated, and surface-modified polypyrrole films were studied by angle-dependent X-ray photoelectron spectroscopy (XPS). The morphology of the PPY surface after modification by graft copolymerization was revealed by atomic force microscopy (AFM). The results showed that the density of surface grafting decreased with ozone pretreatment. Surface grafting of the two polymeric acids also gave rise to a self-protonated surface structure. A substantial proportion of the grafted protonic acid groups at the surface remained free for further surface functionalization. The surface characteristics, in particular the charge-transfer interactions and the changes in the intrinsic redox states of the substrate films, associated with the external protonation and surface self-protonation processes were also discussed.

Enzymatic activity of glucose oxidase covalently wired via viologen to electrically conductive polypyrrole films

“…2b) shows a predominant peak at 399.4 eV assigned with the -NHspecies and a high binding energy tail above 400 eV attributable to N + . The N + /N ratio of 0.32 is consistent with the doping level of PPY reported in a previous study (Zhang et al, 1996). After CVV-graft polymerization on the PPY film, a peak at about 288.7 eV associated with the carboxylic acid group is observed in the C 1s spectrum (Fig.…”

Physicochemical and blood compatibility characterization of polypyrrole surface functionalized with heparin

“…1b) indicates a predominant peak at 399.4 eV due to the NH species and a high binding energy tail above 400 eV, attributable to positively charged nitrogen. The N + /N ratio was 0.25, consistent with the doping level of PPY reported in a previous study (Zhang et al, 1996). After PEGMA grafting, the overall intensity of the N 1s core-level spectrum (Fig.…”

Molecularly Imprinted Polymer Nanomaterials for Mycotoxin Extraction

“…Furthermore, it has been revealed by N1s X-ray photoelectron spectroscopy (XPS) studies that the hydrogen of N-H on the pyrrole ring undergoes protonation acidic conditions. Under alkaline conditions, the N-H will be deprotonated (49). The removal of OTA template molecules from MIPPy could be achieved by perturbing the hydrogen bonding between the OTA analyte and the MIPPy binding cavity using a high pH.…”