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.