β Phase Formation in Poly(9,9-di-<i>n</i>-decylfluorene) Thin Films

Bright, Daniel W.; Galbrecht, Frank; Scherf, Ullrich; Monkman, Andrew P.

doi:10.1021/ma101570u

Cited by 36 publications

(39 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the assemblies are assumed to be quasi-two-dimensional membranes, the isotropic phase transition temperature (T * mem ) for the membrane generally increases with decreasing N [33] and is unattainable for PF6. At room temperature, the optical characteristics matching those of the PF8 β phase are found for PF7 and PF9 in MCH both at high (∼1 vol %) [32] and low (∼0.002 vol %) [34] concentrations, while the same is seen for PF10 in thin films [35], with its thermal dependency following the lower T * mem [33]. The presence of sheetlike assemblies [26] or membranes [33] in PFs mixed with MCH (or PF N -MCH) is well established and discussed in terms of their internal structure [32] and macrophase separation [30], thermal behavior [30,32], and the existence of β phase [25,34,35].…”

Section: Kitts and Vanden Boutsupporting

confidence: 54%

“…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 * . These findings give us the following scenarios.…”

Section: Resultsmentioning

confidence: 96%

“…II)? Bright et al [34,35] suggest that chain planarization in PF N -MCH is the result of side chain interactions between separate chromophores, even if the two interacting segments are on the same chains.…”

Section: Resultsmentioning

confidence: 99%

“…The β phase involves a planarization of the backbone [13,14] which may be driven by the external environment. Bright et al [35] studied the optical trace of the β phase in MCH for N = 6−10 and proposed that its formation is balanced between two factors. The tendency for polymer assemblies decreases with increasing N, but the van der Waals bond energy available to overcome the steric repulsion and planarize the backbone increases with increasing N. This leads the proportion of β phase to reach a peak at N = 8.…”

Section: B Agglomeration Of Polyfluorene Sheetsmentioning

confidence: 99%

“…The solvent and solution phases coexist inside the cuplike region. We learn from experiment that the case N = 10 is in the single phase region at room temperature [33,35] and therefore has lowχ . We can thus mark the concentration f 10 = f exp .…”

Section: B Agglomeration Of Polyfluorene Sheetsmentioning

confidence: 99%

See 4 more Smart Citations

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

et al. 2011

View full text Add to dashboard Cite

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.

show abstract

Section: Kitts and Vanden Boutsupporting

confidence: 54%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: B Agglomeration Of Polyfluorene Sheetsmentioning

confidence: 99%

Section: B Agglomeration Of Polyfluorene Sheetsmentioning

confidence: 99%

See 3 more Smart Citations

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

et al. 2011

View full text Add to dashboard Cite

show abstract

Methods for Controlling Structure and Photophysical Properties in Polyfluorene Solutions and Gels

2013

Self Cite

View full text Add to dashboard Cite

Knowledge of the phase behavior of polyfluorene solutions and gels has expanded tremendously in recent years. The relationship between the structure formation and photophysics is known at the quantitative level. The factors which we understand control these relationships include virtually all important materials parameters such as solvent quality, side chain branching, side chain length, molecular weight, thermal history and myriad functionalizations. This review describes advances in controlling structure and photophysical properties in polyfluorene solutions and gels. It discusses the demarcation lines between solutions, gels, and macrophase separation in conjugated polymers and reviews essential solid state properties needed for understanding of solutions. It gives an insight into polyfluorene and polyfluorene beta phase in solutions and gels and describes all the structural levels in solvent matrices, ranging from intramolecular structures to the diverse aggregate classes and network structures and agglomerates of these units. It goes on to describe the kinetics and thermodynamics of these structures. It details the manifold molecular parameters used in their control and continues with the molecular confinement and touches on permanently cross-linked networks. Particular focus is placed on the experimental results of archetypical polyfluorenes and solvent matrices and connection between structure and photonics. A connection is also made to the mean field type theories of hairy-rod like polymers. This altogether allows generalizations and provides a guideline for materials scientists, synthetic chemists and device engineers as well, for this important class of semiconductor, luminescent polymers.

show abstract

An In Situ Investigation into the Formation of the Solvent‐Induced Crystalline Phase of Poly(9,9‐Dioctylfluorene) in Solvent Vapor Annealing

Yang

et al. 2016

Macro Chemistry & Physics

View full text Add to dashboard Cite

A new metastable solvent‐induced clathrate liquid crystalline phase of β phase (named β' here) in crystalline poly(9,9‐dioctylfluorene) (PFO) thin film induced by solvent annealing is found by a combination of in situ ultraviolet and visible spectrophotometry (UV‐vis), photoluminescence spectroscopy (PL), and grazing incidence wide‐angle X‐ray scattering (GIWAXS). The solvent annealing process consists of three processes: diffusion of solvent molecules into the film; saturation of solvent in the film; and drying of the film under nitrogen. The formation of β' phase with ordered packing of side chains and disordered packing of backbones occurs during the diffusion process of solvent molecules into the film. When the solvent molecules penetrate the film, the disordered side chains start to align themselves to form an ordered structure, and the ordering would gradually in the saturationprocess. Furthermore, the ordering of side chains drives an ordered rearrangement of the backbones during the drying process; however, the crystallinity of the side chains decreases with the orderly rearrangement of backbones due to the helical conformation of PFO.

show abstract

β Phase Formation in Poly(9,9-di-n-decylfluorene) Thin Films

Cited by 36 publications

References 19 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

Methods for Controlling Structure and Photophysical Properties in Polyfluorene Solutions and Gels

An In Situ Investigation into the Formation of the Solvent‐Induced Crystalline Phase of Poly(9,9‐Dioctylfluorene) in Solvent Vapor Annealing

Contact Info

Product

Resources

About