Papers by Keyword: Conjugated Polymer

Abstract: A copolymer based on 1,4-di(thiophen-3­yl)benzene and pyrene was electrochemically synthesized and characterized. The copolymer film showed a stable and well-defined redox process. Furthermore, five various colors under different potentials were presented on the copolymer film. Besides, the copolymer film showed fast switching time (1.5 s at 750 nm, 1.0 s at 1100 nm). Cyclic voltammetry study reveals that the copolymer film has reasonable stability.

Abstract: The new comb-copolymers [polyacetylene–MPEG (polyethylene glycol monomethyl ether)] were synthesized with (nbd)Rh⁺[η⁶-C₆H₅B^- (C₆H₅)₃] as catalyst. The copolymers with moderate molecular weights (Mn) (13000-170000) and yields (31.6-47.3%) exhibited higher optical activities compared with chiral monomer, which accorded with the “Chiral Amplification” effect. The optical activity of the copolymers gradually decreased as the amount of MPEG increased. The maximum amounts of MPEG for successful copolymerization and optical activity of copolymers were 40%, 30%, 20%(mol%) as the Mn of MPEG was 350, 750,1900, respectively. The optical activity of copolymers could change at external environmental stimulation, e.g., decreased as methanol content increased.

Abstract: A novel linear conjugated polymer, poly(cyclopenta-1,3-diene), is designed. The electronic structures of poly(cyclopenta-1,3-diene) is calculated with extended Hückel tight binding program. The calculated band gap of the polymer is about 1.1 eV, which suggests this kind of conjugated polymer can be used in infrared optoelectronic devices.

Abstract: Conjugated polymers with a stabilized blue emission are of importance for the realization of large flat panel AMOLED displays using polymer light-emitting diodes. Several novel conjugated polymers using newly developed templates for the stabilized EL emission are reported. Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a new class of blue-emitting polymers utilizing a new back-bone. This material emits a efficient blue EL without exhibiting any unwanted peak in the long wavelength region (green region) even after prolonged annealing at an elevated temperature of 150oC in air, or operation of the device. New electroluminescent spiro-PCPPs, poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene))) (spiro-PCPP-alt-PCPP) and poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(1,4-phenylene)) (spiro-PCPPP), have been synthesized by the Suzuki polymerization. The PL emission spectra of polymers in THF solution show a same maximum peak at 397 nm. The maximum PL emission spectra of polymers appeared at around 463 and 456 nm in solid state, respectively. The PL spectra in solid thin films show more red-shifted over 60 nm than solution conditions. The blue emissions at 400-409 nm for the π–π* transitions of conjugated polymer backbone are almost completely quenched or decreased.

Abstract: The present investigation deals with the synthesis, characterization and EL of new copolymers, CzCNPFV1, CzCNPFV2 and CzCNPFV3 by Knoevenagel condensation reaction. The CzCNPFVs was synthesized for promoted efficiency of reported CNPFV. The PL emission spectra of the CzCNPFVs in chloroform solution show maximum peaks at 476 ~ 479 nm. In thin films, maximum peaks of the CzCNPFVs appeared at 501 ~ 504 nm, red-shifted around 25 nm as compared to that in solution. The more negative energy of the LUMO of CzCNPFV1 or CzCNPFV2 indicates the electron injection process is easier than in CNPFV. From this result, higher quantum efficiency of CzCNPFV1 or CzCNPFV2 as compared to that of CNPFV can be expected due to its improved electron injection ability from the cathode.

Abstract: We investigate the dynamics of charged states (polarons) in bulk heterostructures of polythiophene and fullerene derivatives by means of photoinduced absorption spectroscopy, and is compared them with those in pristine polythiophene thin films. Polaron lifetimes in the bulk heterostructure and in polythiophene thin films at 6 K exceed 140 and 17 μs, respectively. The difference in lifetime indicates that charged states are better stabilized by the addition of the fullerene derivative. We also find that the dynamics of intrachain singlet excitons, which are not observed in the bulk heterostructure, are different from that of polarons in polythiophene thin films.

Abstract: Measurements of nonlinear optical properties of a newly synthesized thiophene based polymer are reported. The nonlinear transmission measurements were performed on the polymer dissolved in N,N-dimethylformamide by employing the single beam Z-scan technique using a Q-switched laser output at 532-nm. The polymer shows strong optical limiting behavior, where the transmittance decreases when the pump fluence is increased. It was found that an effective three-photon absorption (3PA) model at the excitation wavelength gives the best fit to the obtained experimental data. The value of the 3PA coefficient has been numerically calculated. This study clearly reveals the potential of new polymeric material has, for optical limiting applications.

Abstract: Conducting polymer actuators are of interest in applications where low voltage and high work density are beneficial. These actuators are not particularly fast however, with time constants normally being greater than 1 second. Strain in these actuators is proportional to charge, with the rate of charging being found to limit the speed of actuation. This rate of charging is in turn limited by a number of factors, the dominant factor depending on the actuator and cell geometry, the potential range, the composition and the timescale of interest. Mechanisms that slow response can be as simple as the RC charging time arising from the actuator capacitance and the series resistances of the electrolyte and the contacts, or may involve polymer electronic or ionic conductivities, which can in turn be functions of potential. Diffusion can also be a factor. An approach is presented to help estimate the relative magnitudes of these rate limiting factors, thereby enabling actuator designs to evaluated and optimized for a given application. The general approach discussed is also useful for analyzing rate limits in carbon nanotube actuators and other related technologies.