Molecular rearrangements observed by single-molecule microscopy

We have applied quantitative single-molecule photoluminescence microscopy for directly observing molecular rearrangements in a polymeric material subjected to tensile deformation. The system examined is a blend of fluorescent conjugated polymer molecules embedded in polyethylene, known to exhibit strong phase separation. Statistical analysis of the sizes of phase-separated domains reveals that during tensile deformation large domains of fluorescent molecules are transformed into smaller clusters and ultimately isolated single molecules. In addition to elucidating the nature of the stretch-induced morphology change, our work underscores the fundamental value of single-molecule techniques for material analysis [1].