Segmental Alignment in the Aggregate Domains of Poly(9,9-dioctylfluorene) in Semidilute Solution

Rahman, M. Habibur; Chen, Chun-Yu; Liao, Shao-Ching; Chen, Hsin‐Lung; Tsao, Cheng‐Si; Chen, Jean-Hong; Liao, Jing-Long; Иванов, В. А.; Chen, Show‐An

doi:10.1021/ma071036f

Cited by 48 publications

(81 citation statements)

References 46 publications

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“…41,67 During the cooling process, the β-phase content will greatly increase owing to the side-chain interactions. 68,69 When temperature decreases to 69-60°C, the single-layered β-sheet can be smoothly converted from isotropic phase according to our STM results, followed by the formation of cylinder clusters with a thickness of 14.9 nm via the sheetlike aggregate by SAXS. Because cylinder clusters effectively dominated the PFO-enriched phase, the extensive cross-linked networks are formed by the phase separation with isotropic polymer chains.…”

Section: ' Introductionsupporting

confidence: 67%

Preparation and Characterization of Polyfluorene-Based Supramolecular π-Conjugated Polymer Gels

Lin¹,

Shi²,

et al. 2011

J. Phys. Chem. C

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During the past decades, π-conjugated polymers have been studied intensively owing to their potential applications in organic optoelectronic devices, such as polymeric light-emitting diodes, bulk heterojunction solar cells, organic field-effect transistors (OFETs), organic memories, biosensors, and actuators. 1,2 The performance of organic devices is determined not only by the inherent electronic structures of individual polymer chain 3,4 but also by multiscale morphologies that were constructed by the drive of supramolecular interactions or van der Waals' forces. Many efforts have been made to design the controllable welldefined nanostructures or hierarchically ordered assemblies in the field of supramolecular semiconductors and electronics for the high-performance or new functional devices. 5,6 One typical example is that ordered self-organization of polythiophenes dramatically influences the performance of bulk heterojunction photovoltaic cells as well as the mobility of OFETs. 7,8 Lightemitting polyfluorenes (PFs) is another impressive example of polymorphisms, including amorphous phase, semicrystalline (R-) phase and R 0 -phase, β-phase, and nematic liquid crystalline (N-) phase. These abundant phases provide a unique opportunity to study the relationship between phase morphology and device performances. 9-13 For example, PFO thin film containing the β-phase exhibits the excellent spectral stability in PLEDs and the pumped lasers with low threshold. 14-16 In this context, it is of the utmost importance to explore further the unique morphology and phase of π-conjugated polymers, which are based on its unique self-assembly mode and supramolecular interactions. Supramolecular gel is a fascinating state that appears solid-like and yet is composed predominantly of a liquid and a small amount of gelators stabilized by supramolecular interactions with 3D networks. 17-20 Until now, low-molecular-mass organogels (LMOGs) have been applied in a wide range of fields, such as biomimetics, separations, drug delivery, soft templates, and tissue engineering. 21-24 Steroid or lipid units have served as gelators to generate cross-linking points in the 3D networks. 25 In addition, some electronically inactive comb-shaped polymers (isotactic and syndiotactic polystyrene (PS), 26 poly(methyl methacrylate), 27 and polyesters 28 ) have also been found to form gel networks easily owing to their unique helical conformations. However, little attention has been paid to π-conjugated polymers. 29-32 Supramolecular π-conjugated polymer gels (SCPGs) can be served as one kind of semiconducting soft materials with distinguished porous structures that may find applications in nanosensors, 33 mimic-artificial muscle, 34 super capacitor, 35 and lithium battery material. 36 Poly(3-alkylthiophene)-based gels were prepared by quenching xylene solution at 150°C, and its conductivity was improved. 37,38 ABSTRACT: Supramolecular π-conjugated polymer-based gels (SCPGs) are one important kind of semiconducting soft materials. Herein we demonstrate a p...

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Section: ' Introductionsupporting

confidence: 67%

Preparation and Characterization of Polyfluorene-Based Supramolecular π-Conjugated Polymer Gels

Lin¹,

Shi²,

et al. 2011

J. Phys. Chem. C

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“…9 We have shown that PF8 chains aggregated to form networks containing domains of aligned segments in the semidilute toluene solution. 15 In MCH the majority of PF8 chains were found to form bilayered sheetlike aggregates. The formation of these aggregates was often accompanied by the appearance of a mesomorphic β-phase in which the PF8 chains adopt the C β conformation.…”

Section: Introductionmentioning

confidence: 99%

Phase-Separation-Induced Gelation of Poly(9,9-dioctylfluorene)/Methylcyclohexane Solution

et al. 2010

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The gelation behavior of the solution of a conjugated polymer, poly(9,9-dioctylfluorene) (PF8), with a poor solvent, methylcyclohexane (MCH), induced by aging at room temperature has been investigated. Light scattering and optical microscopy revealed that the gelation was driven by a macrophase separation occurred through a spinodal decomposition mechanism. Although the spinodal decomposition could proceed to the late stage, the interconnected morphology was arrested to give rise to the gel property of the system. The phase-separated gel was composed of an isotropic phase and a PF8-enriched liquid crystalline phase. The liquid crystalline phase was further found to consist of sheetlike aggregates (as revealed by smallangle X-ray scattering) in which a fraction of the PF8 chains formed the β-phase (as disclosed by the optical spectra) which dominated the photoluminescence spectrum of the gel. The PF8/MCH gel could be disintegrated by moderate heating to ca. 70°C. This gel-to-sol transition was accompanied by the disruptions of the sheetlike aggregates and the β-phase which led to homogenization of the solution.

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“…22 The network-like structures are, moreover, observed for PF8/toluene mixtures at higher concentrations. 24 The role of side chain length in the formation of these assemblies remains unclear. Even though the effects of side chain length have been extensively studied for non-conjugated polymers such as polymers with a polymethacrylate main and polystyrene side chains, 25 the literature on the effects of side chain length on the phase behavior of PFs remains relatively sparse, consisting of basically comparison between PF8 and poly(9,9-dihexylfluorene) (PF6) 26 as well as poly(9,9-dihexylfluorene-alt-dialkoxybenzene) copolymers.…”

Section: Introductionmentioning

confidence: 99%

Influence of Side Chain Length on the Self-Assembly of Hairy-Rod Poly(9,9-dialkylfluorene)s in the Poor Solvent Methylcyclohexane

et al. 2007

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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. PF6/MCH, PF7/MCH, PF8/MCH, and PF9/MCH form large (10-100 nm) sheetlike assemblies (thickness of 2-3 nm). The larger length scale structures of these sheets show an odd-even dependence on the side chain (spacer) length: the PF6 and PF8 sheets are broader and thinner, whereas PF7 and PF9 sheets are thicker with a putative double layer structure. PF10 does not follow this sequence, and only part of the polymer is assembled into a sheetlike structure, the rest remaining dissolved at the molecular level. PF8/MCH and PF9/MCH mixtures also have lower length scale crystalline structures with an internal period corresponding to the periodicity observed in the solid-state phase of PF8. Vestiges of crystalline domains are found for PF6 and PF7 but not for PF10. PF7/MCH, PF8/MCH, and PF9/MCH systems contain the conformational isomer C , of those chains observed in the phase, while this is not observed with other polymer/MCH systems.

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Segmental Alignment in the Aggregate Domains of Poly(9,9-dioctylfluorene) in Semidilute Solution

Cited by 48 publications

References 46 publications

Preparation and Characterization of Polyfluorene-Based Supramolecular π-Conjugated Polymer Gels

Preparation and Characterization of Polyfluorene-Based Supramolecular π-Conjugated Polymer Gels

Phase-Separation-Induced Gelation of Poly(9,9-dioctylfluorene)/Methylcyclohexane Solution

Influence of Side Chain Length on the Self-Assembly of Hairy-Rod Poly(9,9-dialkylfluorene)s in the Poor Solvent Methylcyclohexane

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