Studying conductive polymer coating (BAM-PPV) using positron annihilation spectroscopy

Positron annihilation spectroscopy has been used to study two conductive polymer coatings, Al‐507A and Al‐507B, consisting of BAM‐PPV (poly (bis‐dialkylamino) phenylene vinylene) dissolved in two different solvents, THF at 0.2% concentration and xylene at 1.0% concentration, respectively. These samples were sprayed on aluminum substrates. They were further subjected to neutral salt treatment for 240 hours for the corrosion test. Doppler broadening of annihilation radiation (DBAR) and positron annihilation lifetime spectroscopy (PALS) were employed to investigate the corrosion effect on the two coatings in addition to their free volume. It was found that there are two layers in the polymer topcoat of sample Al‐507A while they were not clearly seen in Al‐507B. Interestingly the near‐surface layer demonstrates a large change after the salt treatment, suggesting creation of extra free volume. Both DBAR and PALS measurements indicate that the amount of free volume for Al‐507B coating is more than that for Al‐507A coating, while the free‐volume hole size for both coatings are similar, around 0.32 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)