Theoretical studies of the interaction between aluminum and poly(p-phenylenevinylene) and derivatives

We report the results of a theoretical study of the interaction between aluminum and poly(p-phenylenevinylene) and derivatives of poly(p- phenylenevinylene). This allows us to investigate the initial stages of formation of the metal/conjugated polymer interface. Applying the semiempirical Austin model 1 method, we find that aluminum reacts preferentially by forming covalent bonds with the vinylene linkages in both poly(p-phenylenevinylene) and poly(2,5-dimethoxy-p-phenylenevinylene). When carbonyl groups replace the methoxy groups, i.e., to form poly(2,5-dialdehyde-p-phenylenevinylene), new reactive sites are induced, leading to structures involving aluminum-oxygen bonds, with stabilities comparable to those involving reaction with the vinylene groups. In all of the three systems investigated, the interaction with aluminum induces major modifications of the polymer chains with interruptions of the π system caused by formation of sp³ sites. Charge distribution analysis indicates that electron charge transfer takes place from the aluminum atoms to the polymer chains.