X-ray photoelectron spectroscopy and scanning electron microscopy characterization of novel poly(monosubstituted) acetylenes containing doping species

The chemical structure of two homogeneously doped polyenes, namely poly(propargylalcohol) (PPOH) and poly(N,N-dimethylpropargylamine) (Pd-PDMPA), has been investigated by means of x-ray photoelectron spectroscopy (XPS). The study of FeCl3 and I2 doped PPOH films gave evidence of different chemical states for the dopants into the polymeric chain. This result confirms that a charge transfer reaction between the polymer and dopant occurs, as found for analogous systems. An interaction between PPOH and the FeCl3 species, involving the metal and the pendant groups of the polymer, is observed. The analysis of HCl doped Pd-PDMPA films shows that the dopant interacts with the polymer by an acid-base reaction leading to the protonation of the N atoms. Scanning electronic microscopy images of the PPOH and Pd-PDMPA pristine films show that the final result of the polymerization process is the formation of a flat, enamel-like surface. The chain growth of Pd-PDMPA occurs by a dendrite growth. The enamel-like surface of the PPOH films is maintained upon homogeneous doping reaction, whereas a "craquelet " effect is observed when the pristine films are exposed to iodine vapors. Homogeneous doping of Pd-PDMPA with HCl exhibits a dramatic modification of the surface with the appearance of a crystalline structure, due to the acid-base reaction also revealed by the XPS study.