Dopant-polymer interaction: MoCl5-doped polyacetylene

Polyacetylene is doped with MoCl5. The doping levels determined using the method of neutron activation analysis indicate that the atom ratio [Cl]/[Mo] varies from 5 to 1.6, depending on doping time. The C1s XPS (X-ray photoelectron spectroscopy) binding energy (BE) decreases from 283.7 eV for the pristine PA to 282.9 eV, similar to that of WCl6-doped PA as reported in our previous work, but opposite to that of I2- and AsF5-doped PA. The lowering of the BE means that the outer shell electron densities of carbon increase after the doping. The Cl2p XPS of the doped PA shows that there is only one type of chlorine in the adducts. Mo3d XPS shows that there are two states of Mo existing in the doped PA, being state A (MoCl2(CC)4) and state B (Mo(CC)n), quite different from those in the WCl6-doped PA. The level created at 1.72 eV related to state B is closer to the HOMO π orbital (BE 1.8 eV) of the pristine PA, and is therefore a more shallow level than the state created at 1.24 eV (due to state A Mo). Several olefins from more than one PA chain can interact with one Mo atom, allowing electron transfer from one PA chain to another.