Chromophore-Controlled Self-Assembly of Highly Ordered Polymer Nanostructures

Single-molecule excitation polarization anisotropy and molecular dynamics simulations reveal that the folding of polymers composed of conjugated phenylene vinylene (PPV) oligomers joined by flexible linkers can be influenced by the length of the conjugated segments. By varying the number of PPV repeat units from three to five to seven, both the structure and the spectral properties of the polymer can be controlled at the synthetic level. The stronger interactions between longer conjugated units of the polymers lead to more ordered conformations. The mean modulation depth of a septamer containing PPV (M = 0.75) was found to be even higher than that of the traditional homopolymer MEH-PPV (M = 0.66), which suggests that these new polymers provide access to highly aligned nanostructures not typically found in homopolymer systems.