9-Anthryl and 1-pyrenyl groups as reporters of local environments and diffusion of two N,N-dialkylanilines in polyethylene films. Excited state lifetimes determine spatial information

Changes in the static and dynamic fluorescence from two covalently attached lumophores, 1-pyrenyl and 9-anthrylmethyl, induced by the diffusion of two N,N-dialkylanilines, N,N-dimethylaniline and N,N-dioctadecylaniline, within polyethylene films of 42% crystallinity have been examined. The longer lived excited singlet state of 1-pyrenyl is found to report on events occurring within a larger surrounding volume than the much shorter lived excited singlet state of 9-anthylmethyl. In addition, diffusion of N,N-dioctadecylaniline is found to be more rapid than expected on the basis of simple molecular volume considerations and to occur through two parallel pathways. The results suggest that lumophore lifetimes can be ‘tuned’ to interrogate different volumes of host space in polymers.