THERMAL AGING OF TETRAALKYL AMMONIUM DOPED POLYACETYLENES

The stability of tetraalkyl ammonium doped polyacetylenes was examined under accelerated conditions by monitoring the evolution of their intrinsic properties by utilizing electrical conductivity, DSC, and ESR measurements. A first-order rate equation was deduced from the electrical measurements, which leads to an apparent activation energy of about 28 kcal/mol for the counterions studied. A simple mechanism for this inherent instability, which stems from the protonation of the doped sites by the tetraalkyl ammonium ions, was suggested and was verified by elemental analysis and IR spectral studies of the degraded films and also by the gas chromotographic analysis of the degradation products. An ion-exchange method was devised to surpass the 7% doping level attainable by the direct reduction with the R4N+ ion doping agents. The behavior of reduced (3-carotene, considered to be the soluble analogue of the insoluble PA, toward its R4N+ counterion was investigated, and a similar proton abstraction mechanism was put forward to explain its reactivity. In all cases, the order of reactivities of the carbanions were rationalized on the basis of their redox potentials. © 1990, American Chemical Society. All rights reserved.