title: Computational study of the structure, dynamics, and photophysical properties of conjugated polymers and oligomers under nanoscale confinement.
abstract: Computational simulations were used to investigate the dynamics and resulting structures of several para-phenylenevinylene (PPV) based polymers and oligomers (PPV, 2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylene --> MEH-PPV and 2,5,2',5'-tetrahexyloxy-7,8'-dicyano-p-phenylenevinylene --> CN-PPV). The results show how the morphology and structure are controlled to a large extent by the nature of the solute-solvent interactions in the initial solution-phase preparation. Secondary structural organization is induced by using the solution-phase structures to generate solvent-free single molecule nanoparticles. Isolation of these single molecule nanostructures from microdroplets of dilute solution results in the formation of electrostatically oriented nanostructures at a glass surface. Our structural modeling suggests that these oriented nanostructures consist of folded PPV conjugated segments with folds occurring at tetrahedral defects (sp3 C-C bonds) within the polymer chain. This picture is supported by detailed experimental fluorescence and scanning probe microscopy studies. We also present results from a fully quantum theoretical treatment of these systems which support the general conclusion of structure-mediated photophysical properties.
authors.affiliation: Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA. sumpterbg@orn1.gov
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kumar
authors.forename: Adosh
authors.initials: A
authors.lastname: Mehta
authors.forename: Michael D
authors.initials: MD
authors.lastname: Barnes
authors.forename: William A
authors.initials: WA
authors.lastname: Shelton
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Harrison