Excitation trapping in dynamically disordered polymers

Trapping of migrating incoherent electronic excitation by dynamically disordered substitutional traps in a 1-D polymer chain has been studied analyticaly and by means of Monte Carlo simulations. A closed-form analytical solution to the model is based on the assumption that the temporal changes in the spatial coordinates of the traps, due to conformational motion, can be mimicked by a global Poissonian renewal process of the polymer configuration as a whole. The excitation survival probability P(t) for this model of dynamic disorder hopping (DDH) obeys an Ornstein-Zernike-type integral equation, which can be solved analytically in the short- and long-time limits and numerically in the whole time domain. The DDH results are compared with Monte Carlo simulations using discrete and continuous-time random walks showing a good agreement. The relevance of our theoretical findings has been discussed and connections have been made to observations of migrative excitation trapping in aromatic vinyl polymers, where the traps-in the pair approximation-consist of mobile excimer-forming sites (EFS) triggered by the local conformation of a chain.