Electron spin resonance study of poly(ortho-anisidine)/single-walled carbon nanotube composite films: spin dynamics and effects of physisorption processes

Poly(ortho-anisidine) (POA)/single-walled carbon nanotubes (SWCNTs) composite films have been prepared by means of oxidative potentiostatic electropolymerization of the monomer (ortho-anisidine) in the presence of purified SWCNTs. The magnetic properties of the obtained films have been investigated by electron spin resonance (ESR) (ν ∼= 9.4GHz; temperature range 10–300K) and compared with those of pure POA films in the same oxidation state. The similarity of the ESR signals and the dependence on temperature of the ESR line features suggest a polaron origin of the paramagnetic states. A strong increase of the ESR integral intensity has been detected for composite samples kept for 72 h in hydrogen atmosphere at room temperature. Under the same conditions, a less pronounced increase in the intensity has been detected in the case of pure polymer films. The kinetics of the hydrogen adsorption–desorption processes in the nanocomposite samples has been investigated and interpreted in the frame of an H-physisorption mechanism. The comparison between the H-induced effects in POA and nanocomposite POA/SWCNTs films has been carried out taking into account the structure of the samples and the presence of defects.