cyclic voltammograms were taken for these two carbons by varying the scan rate from 5 mV/s to 50 mV/s, the SNU-2 carbon kept the rectangular-shape up to a scan rate of 20 mV/s (Fig. 5b, solid line). In contrast, the MSC-25 carbon showed a deformed cyclic voltammogram at a scan rate of 10 mV/s and a completely collapsed one at a scan rate of 20 mV/s (Fig. 5b, dotted line). A detailed discussion on the electrochemical studies of the material will be presented in a forthcoming paper.In conclusion, we have made a new high surface area mesoporous carbon using Al-HMS as a template. From this research we discovered that the pores of HMS are 3D interconnected, unlike the originally proposed disordered hexagonal structure. The EDLC performance of the carbon material was superior to the commercially available carbon MSC-25 due to improved mesoporosity. The CV of the mesoporous carbon showed ideal rectangular shapes at a high scan rate of 20 mV/s.

Spin-coated films of an ethylhexyl derivative of polyfluorene can be converted on a pretreated polyimide substrate into highly oriented films by annealing in the liquid crystalline state. Together with improving orientation segregation of the wormlike molecules with respect to chain lengths and lamella formation proceeds. End groups are preferentially assembled in interlamellar regions. This morphological feature is thought to influence all measurements of intrinsic properties of polyfluorene films with similar histories. Electron diffraction patterns of the film are identical with X-ray fiber diagrams of fibers drawn from the melt and annealed in the liquid crystalline state. The experimental data show that the polymer molecules adopt a helical (5/q) conformation, packing in a trigonal unit cell. Molecular modeling based on ab initio MO calculations have been carried out to obtain independent estimates of chain geometry and conformation. These calculations are more in favor of a 5/2 rather than a 5/1 helix, with the argument of the observed packing of the individual PF chains and a plausibly low torsion angle of adjacent fluorene building blocks only for a 5/2 helix.

We have studied the dynamics of optically generated excitations in spin-coated glassy films of poly͑9,9-dioctylfluorene͒ ͑PFO͒ and in ␤-phase PFO films using picosecond time resolved photoluminescence ͑PL͒ spectroscopy, performed both at room temperature ͑RT͒ and at 5 K. We also present measurements of the PL emission of PFO and ␤-phase PFO at RT and 5 K following continuous wave ͑cw͒ excitation. We show that the cw emission from ␤-phase PFO at 5 K is very highly resolved, permitting us to make an assignment of the different vibrational modes of the molecule that couple to the S 1 →S 0 transition. Via time-dependent spectroscopy measurements performed at 5 K, we are able to follow exciton diffusion and relaxation through an energetically broadened density of states to polymer chains having a longer conjugation length and lower energy gap. By comparing the relative emission intensity of the different vibronic transitions as a function of time, we are able to directly demonstrate that the lower energy emissive states are associated with longer conjugation length polymeric chains that have enhanced rigidity. At room temperature, we find that these relaxation processes occur faster than the resolution of our detector due to thermally assisted energy migration.

Liquid-crystalline polyfluorene (PF) homopolymers substituted with chiral alkyl side chains were synthesized, and their chiroptical properties in the solid state were investigated by means of circular dichroism (CD), circularly polarized photoluminescence (CPPL), and circularly polarized electroluminescence (CPEL) measurements. Polarization-selective scattering of light is shown to cause artifacts in the circularly polarized absorption and emission spectra in the wavelength range near or above the absorption edge, and a measurement scheme to avoid these is presented. For all derivatives, significant chiroptical effects appeared only after the solid layers have been annealed at elevated temperatures, preferably into the liquid-crystalline state of the polymer. The largest anisotropy factors were measured for a polyfluorene substituted with chiral (R)-2-ethylhexyl side chains, yielding absolute values of up to 0.28 for CPPL and up to 0.25 for CPEL. These are among the highest ever reported for a chiral conjugated polymer. Anisotropy factors for CD, CPEL, and CPPL were consistently found to follow an "odd-even effect" concerning the position of the chiral center in the alkyl side chain. If the chiral center is placed close to the polymer backbone, the CD is dominated by one peak with its maximum close to the maximum of the π-π* absorption band. This indicates that the chiroptical properties are most probably caused by intrachain effects rather than by pure interchain exciton coupling. This interpretation is supported by the results of time-dependent Hartree-Fock calculations for the isolated fluorene dimer and trimer. In both cases, the anisotropy factor depends strongly on the torsion angle between neighboring fluorene units. For the trimer, a maximum anisotropy factor of 0.25, close to the maximum values determined experimentally, is predicted for a torsion angle of ca. 105°. Both experimental and theoretical results indicate that the chiroptical properties of these chiral substituted polyfluorenes are mainly caused by a helical conformation of the conjugated polymer backbone.