Encontrados 14 documentos, a visualizar página 1 de 2
An effect of side chain length on the solution structure of poly(9,9-dialkylflu...
Knaapila, M.; Almásy, L.; Garamus, V. M.; Ramos, M. L.; Justino, L. L. G.; Galbrecht, F.; Preis, E.; Scherf, U.; Burrows, H. D.; Monkman, A. P.The effect of side chain length of [pi]-conjugated poly(9,9-dialkylfluorene)s has been studied in semi-dilute (10 mg/mL) toluene solutions using small-angle neutron scattering (SANS) and 1H and 2H NMR spectroscopies. Under these conditions, SANS data indicate that poly(9,9-dinonylfluorene) and poly(9,9-dioctylfluorene) are dissolved down to the molecule level and appear as elongated one-dimensional chains (leng...
Influence of Side Chain Length on the Self-Assembly
Knaapila, M.; Dias, F. B.; Garamus, V. M.; Almásy, L.; Torkkeli, M.; Leppänen, K.; Galbrecht, F.; Preis, E.; Burrows, H. D.; Scherf, U.; Monkman, A. P.We report on the phase behavior of poly(9,9-dihexylfluorene) (PF6), poly(9,9-diheptylfluorene) (PF7), poly(9,9-dioctylfluorene) (PF8), poly(9,9-dinonylfluorene) (PF9), and poly(9,9-didecylfluorene) (PF10) in methylcyclohexane (MCH). After a heating−cooling cycle, in the 10−50 mg/mL concentration range, PF6/MCH, PF7/MCH, PF8/MCH, and PF9/MCH systems were found to be gel-like, while PF10/MCH appears less viscous....
Triplet-State and Singlet Oxygen Formation in Fluorene-Based Alternating Copoly...
Fonseca, S. M.; Pina, J.; Arnaut, L. G.; Melo, J. Seixas de; Burrows, H. D.; Chattopadhyay, N.; Alcácer, L.; Charas, A.; Morgado, J.; Monkman, A. P.Data are reported on the triplet states of a series of fluorene-based A-alt-B type alternating copolymers based on pulse radiolysis-energy transfer and flash photolysis experiments. From the pulse radiolysis experiments, spectra are given for eight copolymers involving phenylene, thiophene, benzothiadiazole, and oligothienylenevinylene groups. Quantum yields for triplet-state formation (ΦT) have been obtained b...
Influence of Solvent Quality on the Self-Organization of Archetypical Hairy Rod...
Knaapila, M.; Garamus, V. M.; Dias, F. B.; Almásy, L.; Galbrecht, F.; Charas, A.; Morgado, J.; Burrows, H. D.; Scherf, U.; Monkman, A. P.We report on the nanoscale structure and solvent-induced phase behavior of two, nearly similar π-conjugated hairy-rod polymers, branched side chain poly[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (PF2/6) and linear side chain poly[9,9-dioctylfluorene-2,7-diyl] (PFO or PF8), in good and bad (or poor) solventsdeuterated toluene and deuterated methylcyclohexane (MCH)at 20 °C. Small-angle neutron scattering (SANS) mea...
Interactions between surfactants and 1,4-phenylene-[9,9-bis(4-phenoxy-butylsulf...
Burrows, H. D.; Lobo, V. M. M.; Pina, J.; Ramos, M. L.; Melo, J. Seixas de; Valente, A. J. M.; Tapia, M. J.; Pradhan, S.; Scherf, U.; Hintschich, S. I.The interaction between the water-soluble anionic conjugated copolymer poly1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl (PBS-PFP) and various surfactants has been studied in aqueous solution by UV-vis absorption spectra, fluorescence and electrical conductivity. It is suggested from the linear dependence of absorbance, fluorescence and electrical conductivity on concentration that in the a...
Permeation of sodium dodecyl sulfate through polyaniline-modified cellulose ace...
Valente, A. J. M.; Burrows, H. D.; Polishchuk, A. Ya.; Domingues, C. P.; Borges, O. M. F.; Eusébio, M. E. S.; Maria, T. M. R.; Lobo, V. M. M.The preparation of polyaniline (PANi)-cellulose acetate (CA) blends by casting films from a suspension, is reported. Two membranes were prepared from different solvents, one with a homogeneous and the other a heterogeneous dispersion of PANi in CA matrices. The membranes were characterized by X-ray diffraction, SEM, DSC, and FTIR, and the results were compared with those obtained for pure CA and PANi films. The...
On the triplet state of poly(N-vinylcarbazole)
Pina, J.; Seixas de Melo, J.; Burrows, H. D.; Monkman, A. P.; Navaratnam, S.Triplet state properties including transient triplet absorption spectrum, intersystem crossing yields in solution at room temperature and phosphorescence spectra, quantum yields and lifetimes at low temperature as well as singlet oxygen yields were obtained for poly(N-vinylcarbazole) (PVK) in 2-methyl-tetrahydrofuran (2-MeTHF), cyclohexane or benzene. The results allow the determination of the energy value for ...
Hole formation and transfer in poly[9,9-di(ethylhexyl)fluorene] and an amine en...
Burrows, H. D.; Seixas de Melo, J.; Forster, M.; Güntner, R.; Scherf, U.; Monkman, A. P.; Navaratnam, S.Pulse radiolysis has been used to study the positively charged state of isolated chains of poly[9,9-di(ethylhexyl)fluorene] in chloroform solution. This is found to have an absorption maximum at 560 nm and a weaker band around 420 nm. Intermolecular electron transfer is observed from the aromatic amine tri(p-tolylamine) to this species. With the corresponding polyfluorene derivative end-capped by an arylamine, ...
Triplet state dynamics on isolated conjugated polymer chains
Burrows, H. D.; Seixas de Melo, J.; Serpa, C.; Arnaut, L. G.; Miguel, M. da G.; Monkman, A. P.; Hamblett, I.; Navaratnam, S.http://www.sciencedirect.com/science/article/B6TFM-46MD9J0-5/1/ad58ae25c92bd62f507ea5a6a04f467d
Spectral and electrochemical studies on blends of polyaniline and cellulose esters
Marques, A. P.; Brett, C. M. A.; Burrows, H. D.; Monkman, A. P.; Retimal, B.Blends of chemically prepared polyaniline emeraldine base (PANi) with cellulose esters were studied as films by UV-visible spectroscopy and cyclic voltammetry. The cellulose esters used were acetate, propionate, acetate butyrate, and acetate hydrogen phthalate. Films were prepared by casting from N-methylpyrrolidone or formic acid, and the effect of doping by acids on their spectral and electrochemical properti...
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