Synthesis, optical properties and alignment of poly(9,9-dioctylfuorene) nanofibers

Poly(9,9-dioctlylfluorene) (PFO) nanofibers were fabricated by solution template wetting of anodic alumina membranes. Nanofibers with controlled thickness of 23 nm and length between 0.8 and 10 μm, were obtained, regulated by the dimensions of the used template. Nanofibers displayed spectroscopic characteristics associated with the formation of significant percentages of planar and elongated β phase within the amorphous PFO glassy-phase. Optical polarized microscopy displayed high birefringence resulting from the high degree of internal order induced by β phase generation within the fibers. The structural intra-chain reorganization associated with formation of β phase was promoted by the strong geometrical confinement imposed on the material by the porous template during polymer wetting and solvent evaporation. Flow and shear force alignment techniques were used to control the orientation of fabricated PFO nanofibers, yielding to formation of large oriented nanofiber arrays on transparent substrates.