Concentration-Dependent Thermochromism and Supramolecular Aggregation in Solution of Triblock Copolymers Based on Lengthy Oligothiophene Cores and Poly(benzyl ether) Dendrons

Apperloo, Joke J.; Janssen, Raj René; Malenfant, Patrick R. L.; Fréchet, Jean M. J.

doi:10.1021/ma000793+

Cited by 78 publications

(69 citation statements)

References 23 publications

(26 reference statements)

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“…[18] Upon further cooling an additional absorption band appears around 513 nm, which matches with the additional peak observed in the solid state. Similar thermochromic behavior has been observed for polydiacetylenes in solution [32] and other conjugated oligomers [33] and polymers, [34,35] and this has been attributed to either intramolecular conformational changes or intermolecular aggregation effects. Yet, for polymers these are frequently difficult to distinguish.…”

Section: Steady-state Absorption In Solutionsupporting

confidence: 73%

Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes

Pilzak¹,

Baggerman²,

Lagen³

et al. 2009

Chemistry A European J

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A new series of pure, nanometer-sized and highly-soluble homocoupled oligodiacetylenes (HODA) consisting of two symmetrical oligodiacetylene units was synthesized with high yield and on a multi-milligram scale under mild, catalytic Sonogashira conditions. The lambda(max) and the epsilon(max) of absorption for these HODAs show an increase with the chain elongation. The lambda(max) converges to 450 nm for the longest members of the series at micromolar concentration and to 462 nm for thin drop-casted films. An additional red-shifted absorption is observed in the solid state and in solution at low temperatures, which is caused by aggregation. The lambda(max) of the fluorescence emission increases with the chain length and reaches 492 nm for the longest oligomer. The fluorescence quantum yield has its maximum for the shortest oligomer and decreases rapidly for the longer ones. A similar trend is found for the fluorescence lifetime with a maximum of 100 ps for the homocoupled monomer. The rotational correlation time shows a linear increase with the oligomer length. This reveals a significant persistence length and indicates that the HODA molecules are fully stretched molecular rods (up to 8.2 nm).

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Section: Steady-state Absorption In Solutionsupporting

confidence: 73%

Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes

Pilzak¹,

Baggerman²,

Lagen³

et al. 2009

Chemistry A European J

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“…[15] The former involves energy transfer and charge trapping allowing an enhancement of device performance in addition to color tuning and has been studied extensively. Studies on the effects of the tuning of chain conformation on EL are scarce, but studies on the effect of the manipulation of the supramolecular structure on the photoluminescence (PL) of the blue-emitting polymer poly(9,9-di-n-octyl-2,7-fluorene) (PFO) are extensive.…”

mentioning

confidence: 99%

Self‐Dopant Formation in Poly(9,9‐di‐n‐octylfluorene) Via a Dipping Method for Efficient and Stable Pure‐Blue Electroluminescence

et al. 2007

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Molecular design of conjugated polymers for efficient electroluminescence (EL) and color tuning has long been one of the most important subjects in the development of polymer light emitting diodes (PLED) and can be carried out in two ways: by chemical and physical methods. The chemical method, involving the incorporation of charge-transport moieties on the main chain, [1][2][3] flexible side chain, [4][5][6] and chain ends, [7] has been extensively studied for poly(phenylene vinylene)s, polyfluorenes, and other polyarylenes in order to promote balanced hole and electron fluxes and to adjust highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, as well as the band gap for color tuning. Taking polyfluorenes as an example, incorporation of triphenylamine in the main chain and oxadiazole in the side chain provides an improvement in the efficiency and purity of blue emission to 2.07 cd A -1 and a Commission Internationale de l'Eclairage (CIE) value of x + y = 0.29, respectively, which is the best blue fluorescence device that has been reported so far.[1] However, chemical methods require elaborate synthesis.Physical methods include blending a conjugated polymer with dopants, [8][9][10] tuning a chain conformation, [11][12][13][14] and manipulating a supramolecular structure.[15] The former involves energy transfer and charge trapping allowing an enhancement of device performance in addition to color tuning and has been studied extensively. Studies on the effects of the tuning of chain conformation on EL are scarce, but studies on the effect of the manipulation of the supramolecular structure on the photoluminescence (PL) of the blue-emitting polymer poly(9,9-di-n-octyl-2,7-fluorene) (PFO) are extensive. Because of its highly coplanar backbone, PFO can be physically transformed by into a variety of supramolecular structures, [11][12][13][14] such as crystalline phases (i.e., a and a′ phase) and noncrystalline phases (such as amorphous, nematic, and b phase, which has an extended conjugation length of about 30repeat units, as evidenced by wide-angle X-ray diffraction).[16]Among these structures, b phase has attracted the most attention because of its specific physical properties, such as a lower extent of triplet exciton formation, [17] a reduced ability to be photobleached on the single-molecule scale, [18] and efficient energy transfer from the amorphous to the b phase. [19] b phase can be physically formed by dissolving PFO in solvents with lower solvent power and higher boiling points [19] or in a solvent/nonsolvent mixture (for example, chloroform/methanol), [20] by exposing a PFO film to solvent vapors (i.e., hexane, cyclohexane, tetrahydrofuran (THF), or toluene), [16] or by applying specific thermal treatment to a PFO film (cooling and reheating to room temperature). [16] In our previous work, [21] we reported that the use of an electron-deficient moiety (such as triazole) as an end-capper for PFO can induce a trace amount of b phase without any further physical treatme...

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“…In solution, both polymers are green and show minor optical changes upon increase of the temperature between room temperature and 100 8C indicating neither significant disruption of effective conjugation [36,37] nor major aggregation of the backbones once solvated. [38,39] The key incorporation of regiosymmetric ProDOTs bearing two octyloxy solubilizing chains induces sufficient solubility (up to about 8 mg mL À1 in the case of polymer A) for solid thin film processing using common organic solvents. While polymer A shows good to excellent solubility at room temperature in toluene, chloroform and ortho-dichlorobenzene (ODCB), polymer B requires hot mixtures of toluene and chloroform (60 8C) or hot ODCB (80-100 8C) to be efficiently dissolved in solution.…”

mentioning

confidence: 99%

Spray Processable Green to Highly Transmissive Electrochromics via Chemically Polymerizable Donor–Acceptor Heterocyclic Pentamers

2008

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Electrochromic polymers (ECPs) of tunable green: Two symmetrical donor-acceptor based oligomers were designed, synthesized and chemically polymerized affording solution-processable conjugated polymers of distinct green hues in their neutral state. The polyheterocyclic hybrids exhibited highly transmissive oxidized states, excellent optical contrasts both in the visible and in the near infrared, fast switching times and long-term redox switching stability as expected for practical ECP devices.

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Concentration-Dependent Thermochromism and Supramolecular Aggregation in Solution of Triblock Copolymers Based on Lengthy Oligothiophene Cores and Poly(benzyl ether) Dendrons

Cited by 78 publications

References 23 publications

Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes

Synthesis and Optoelectronic Properties of Nanometer‐Sized and Highly Soluble Homocoupled Oligodiacetylenes

Self‐Dopant Formation in Poly(9,9‐di‐n‐octylfluorene) Via a Dipping Method for Efficient and Stable Pure‐Blue Electroluminescence

Spray Processable Green to Highly Transmissive Electrochromics via Chemically Polymerizable Donor–Acceptor Heterocyclic Pentamers

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