Isothermal CIS-trans isomerization of polyacetylene

Summary form only given. Isothermal cis-trans isomerization behavior of polyacetylene films was carefully observed by DSC and it was found that the isomerization ratio y changes with time t by the stretched (fractional) exponential function, 1 - y = exp [ - (k/sub 0/t)/sup /spl alpha/] where k/sub 0/ and /spl alpha/ are constant and 0 < /spl alpha/ < 1. In the cis-trans isomerization, intramolecular cooperative motions of bonds and also the intermolecular cooperative motions among neighboring chains are needed in order to avoid the steric hindrance in the solid state. Intermolecular-diffusion model is proposed to simply describe the intermolecular cooperative motions of neighboring chains. Using the continuous time random walk model, the decay of survival probability of cis unit 1-y can be approximated by the stretched exponential function under the assumption of the distribution of activation energy.