The effect of solvent quality on the chain morphology in solutions of poly(9,9′-dioctylfluorene)

Kitts, Catherine C.; Bout, David A. Vanden

doi:10.1016/j.polymer.2007.02.047

Cited by 72 publications

(77 citation statements)

References 46 publications

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“…Our simple consideration gives values c * ∼ 0.09 vol % and ∼ 0.05 vol %, implying that the condition c c * holds for both cases. Kitts and Vanden Bout note that "the β-phase domains" tend to associate at lower concentrations but lead to visual gelation at higher toluene concentrations (1 wt % or 0.9 vol %, i.e., c > c * ) on cooling [24]. Similarly, Bright et al [35] found the β-phase domains but no gelation for c c * .…”

Section: Resultsmentioning

confidence: 97%

“…Elsewhere, Kitts and Vanden Bout [24] worked with PF8 (M n = 34.8 kg/mol) in 0.001 wt% (or ∼0.0009 vol %) toluene and Dias et al [25] with PF8 (M n = 188 kg/mol) in 3 μg/mL (or 0.0003 vol %) MCH and observed optical characteristics of β phase when cooling the solutions (down to ∼200 K, for example). Our simple consideration gives values c * ∼ 0.09 vol % and ∼ 0.05 vol %, implying that the condition c c * holds for both cases.…”

Section: Resultsmentioning

confidence: 99%

“…A logical first step towards understanding increased structural complexity is to change the side chain length that alters the solid state structure which has been shown so far for poly(9,9-dihexylfluorene) (PF6) [23]. In our notation this factor is characterized by the number of side chain beads, N. [24] studied PF8 and demonstrated how various solvents have significant effects on the optical characteristics matching the twisted and planar polymer chains, with the latter being favored by poor solvents. PF8 in toluene or methylcyclohexane (MCH) [25,26] is an illustrative example of how polymer aggregation is enhanced in the poorer solvent (MCH) or by increasing polymer concentration, decreasing temperature, or aging.…”

Section: Introductionmentioning

confidence: 99%

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Network structure of polyfluorene sheets as a function of alkyl side chain length

et al. 2011

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The formation of self-organized structures in poly(9,9-di-n-alkylfluorene)s ∼1 vol % methylcyclohexane (MCH) and deuterated MCH solutions was studied at room temperature using neutron and x-ray scattering (with the overall q range of 0.000 58-4.29Å−1 ) and optical spectroscopy. The number of side chain carbons (N ) ranged from 6 to 10. The phase behavior was rationalized in terms of polymer overlap, cross-link density, and blending rules. For N = 6−9, the system contains isotropic areas and lyotropic areas where sheetlike assemblies (lateral size of >400Å) and free polymer chains form ribbonlike agglomerates (characteristic dimension of >1500Å) leading to a gel-like appearance of the solutions. The ribbons are largely packed together with surface fractal characteristics for N = 6−7 but become open networklike structures with mass fractal characteristics for N = 8−9, until the system goes through a transition to an isotropic phase of overlapping rodlike polymers for N = 10. The polymer order within sheets varies allowing classification for loose membranes and ordered sheets, including the so-called β phase. The polymers within the ordered sheets have restricted motion for N = 6−7 but more freedom to vibrate for N = 8−9. The nodes in the ribbon network are suggested to contain ordered sheets cross-linking the ribbons together, while the nodes in the isotropic phase appear as weak density fluctuations cross-linking individual chains together. The tendencies for macrophase separation and the formation of non beta sheets decrease while the proportion of free chains increases with increasing N. The fraction of β phase varies nonlinearly, reaching its maximum at N = 8.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Network structure of polyfluorene sheets as a function of alkyl side chain length

et al. 2011

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“…[7][8][9][10][11][12] Films formed from these gelled networks can be used as fl exible platforms in the design of organic electronic devices because they usually have much higher conductivities than comparable fi lms generated under traditional conditions. [ 9,13 ] Understanding and tuning the self-assembly of conjugated polymer in these organogels, therefore, grants the opportunity to engineer these structures to directly benefi t performance.…”

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confidence: 99%

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

Lee

Yin

Holt

et al. 2015

Adv Funct Materials

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Poly(3-hexyl thiophene) (P3HT) is widely regarded as the benchmark polymer when studying the physics of conjugated polymers used in organic electronic devices. P3HT can self-assemble via π-π stacking of its backbone, leading to an assembly and growth of P3HT fi brils into 3D percolating organogels. These structures are capable of bridging the electrodes, providing multiple pathways for charge transport throughout the active layer. Here, a novel set of conditions is identifi ed and discussed for P3HT organogel network formation via spin coating by monitoring the spin-coating process from various solvents. The development of organogel formation is detected by in situ static light scattering, which measures both the thinning rate by refl ectance and structural development in the fi lm via off-specular scattering during fi lm formation. Optical microscopy and thermal annealing experiments provide ex situ confi rmation of organogel fabrication. The role of solution characteristics, including solvent boiling point, P3HT solubility, and initial P3HT solution concentration on organogel formation, is examined to correlate these parameters to the rate of fi lm formation, organogel-onset concentration, and overall network size. The correlation of fi lm properties to the fabrication parameters is also analyzed within the context of the hole mobility and density-of-states measured by impedance spectroscopy.

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“…A literatura tem mostrado que essa fase pode ser desfeita, de maneira irreversível, quando a solução de polímero é submetida ao aquecimento [70]. A análise global da superfície de decaimento do PF-mostrou uma dinâmica …”

Section: Absorção E Fluorescência Estacionáriasunclassified

Fotoquímica de polímeros conjugados contendo centros de transferência de carga e migração de energia

Simas¹

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A Deus pela oportunidade de reforma pessoal através do trabalho edificante. Pelo amparo constante nos momentos de incerteza, medo e desânimo.Ao Prof. Dr. Marcelo Henrique Gehlen pela oportunidade, orientação e, sobretudo, pelas valiosas lições de trabalho.À CAPES pela bolsa concedida e à FAPESP e CNPq pelo suporte financeiro.Ao IQSC pelo apoio institucional.À Profª Drª Leni Akcelrud e ao Arnaldo Glogauer por terem cedido os polímeros PFOPPV e PFPPV.Ao Prof. Dr. Roberto G. S. Berlinck e à aluna Simone P. de Lira pelas análises de LC-MS dos compostos M2 e BNI.Ao Prof. Dr. Benedito S. Lima Neto pela grande assistência na síntese, e análises de GPC, dos polímeros PF-BNI e PF. E em especial, aos alunos José Luiz S. Sá e Gustavo Metzker, pela imensa boa vontade com que prontamente se dispuseram a me ajudar com os procedimentos em atmosfera inerte, requeridos na síntese dos polímeros.Ao Prof. Dr. Lino Misoguti e ao aluno Jonathas P. Siqueira pelas medidas de transiente de absorção dos polímeros PF-BNI e PF.À Profª Drª Melissa F. S. Pinto, pelos cálculos químico-quânticos dos compostos BNI e FBNI.Aos técnicos do CAQI, Mauro Fernandes, Paulo Cordeiro e Sylvana Agustinho pelo auxílio com as técnicas espectroscópicas e cromatográficas.Ao grupo de Fotoquímica pelo auxílio constante nos percalços e necessidades diárias. À Bernadete Figueiredo, pelo esforço para conseguir os artigos e livros pedidos por mim em tempos de greve.Aos amigos do Laboratório de Fluorescência Molecular, Ana, Carol, Denís, Rafael e Robson pela grande ajuda, torcida e descontração, durante todo esse tempo.À Maria Silva Zoccoli pelo imenso apoio e ajuda sincera ao longo de quase dez anos.Aos queridos amigos Ângela, Arnaldo, Carolina, Juliano, Raphaela, Thaís e Vitor, pelo carinho, apoio e camaradagem de sempre.À minha família amada, representação sublime dos valores mais elevados da vida, pelo afeto sincero e incondicional, que justifica e dá sentido a tudo na vida. Whereas the PFPPV backbone is fully conjugated, the chromophore segment in PFOPPV backbone is confined between aliphatic (-(CH 2 ) 8 -) flexible segments. The excited-state dynamics of both copolymers is characterized by the presence of conjugated moieties containing cis and trans isomers. The segmented structure of PFOPPV allows the resonant energy transfer between the chromophores, which is provided by dipole-dipole interactions. The energy transfer process leads to the depolarization of PFOPPV fluorescence emission. For PFPPV the energy migration occurs in less than 20 ps and the fluorescence decay is ascribed to the emission of chromophore segments containing cis and trans, already in a photostationary condition. Dessa forma, a viabilidade de aplicação dos polímeros conjugados em eletrônica molecular, requer o conhecimento da dinâmica e dos mecanismos de relaxação de estado excitado desses materiais. Torna-se então necessária a determinação de parâmetros importantes, tais como escala de tempo e distância, envolvidos nos processos de transferência de energia de excitação eletrônica em p...

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The effect of solvent quality on the chain morphology in solutions of poly(9,9′-dioctylfluorene)

Cited by 72 publications

References 46 publications

Network structure of polyfluorene sheets as a function of alkyl side chain length

Network structure of polyfluorene sheets as a function of alkyl side chain length

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

Fotoquímica de polímeros conjugados contendo centros de transferência de carga e migração de energia

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