Investigations of rodlike polyelectrolytes in solution by small-angle x-ray scattering

Guilleaume, Birgit; Blaul, Jürgen; Wittemann, Matthias; Rehahn, Matthias; Ballauff, Matthias

doi:10.1088/0953-8984/12/8a/331

Cited by 28 publications

(55 citation statements)

References 26 publications

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“…32 Therefore, the observed ordering in the considered dilute solutions (∼1 wt %) is certainly not caused by steric effects but rather by the electrostatic repulsive interactions induced by the charged PBS-PFP molecules. This ordering should not be a surprise as the counterion sensitive order and a reflection at low q due to electrostatic repulsion have been reported also for example for aqueous PPP [8][9][10] and MBL-PPV 11 polyelectrolytes.…”

Section: Discussionsupporting

confidence: 66%

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

Knaapila¹,

Garamus²,

Pearson³

et al. 2006

J. Phys. Chem. B

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We report on the solubilization, phase behavior, and self-organized colloidal structure of a ternary waterpolyfluorene-surfactant (amphiphile) system comprised of polyelectrolytic poly{1,4-phenylene[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) in nonionic pentaethylene glycol monododecyl ether (C 12 E 5 ) at 20°C. We show in particular how a high amount (milligrams per milliliter) of polyfluorene can be solubilized by aqueous C 12 E 5 via aggregate formation. The PBS-PFP and C 12 E 5 concentrations of 0.31 × 10 -4 -5 × 10 -4 M and 2.5 × 10 -4 -75 × 10 -4 M, respectively, were used. Under the studied conditions, the photoluminescence (PL), surface tension, static contact angle, and (π-A) isotherm measurements imply that D 2 O-PBS-PFP(C 12 E 5 ) x realizes three phase regimes with an increasing molar ratio of surfactant over monomer unit (x). First, for x e 0.5, the mixture is cloudy. In this regime polymer is only partially dissolved. Second, for 1 e x e 2, the solution is homogeneous. In this regime polymer is dissolved down to the colloidal level. Small-angle neutron scattering (SANS) patterns indicate rigid elongated (polymer-surfactant) aggregates with a diameter of 30 Å and mean length of ∼900 Å. The ratio between contour length and persistence length is less than 3. Third, for x g 4, the solution is homogeneous and there is cooperative binding between polymer and surfactant. Surface tension, contact angle, and surface pressure remain essentially constant with increasing x. A PL spectrum characteristic of single separated polyfluorene molecules is observed. SANS curves show an interference maximum at q ∼ 0.015 Å -1 , indicating an ordered phase. This ordering is suggested to be due to the electrostatic repulsion between polymer molecules adsorbed on or incorporated into the C 12 E 5 aggregates (micelles). On dilution the distance between micelles increases via 3-dimensional packing. In this regime the polymer is potentially dissolved down to the molecular level. We show further that the aggregates (x ) 2) form a floating layer at the air-water interface and can be transferred onto hydrophilic substrates.

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Section: Discussionsupporting

confidence: 66%

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

Knaapila¹,

Garamus²,

Pearson³

et al. 2006

J. Phys. Chem. B

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“…Even in the case of polyelectrolytes, poly(p-phenylene)-type polymers have been found to take rodlike conformation in solution regardless of concentration or strength of intermolecular interaction. 35 Therefore, if the copolymers are predominantly rigid in the high concentration regime, we assume that this is also the case for dilute solutions. In Figure 3a, plots of SANS data of PF/FL 0.01 , PF/FL 0.10 , and PF/FL 0.25 solutions are given in log-log representations.…”

Section: Resultsmentioning

confidence: 99%

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

et al. 2006

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The luminescence decay kinetics of polyfluorene copolymers containing fluorenone units randomly distributed along the polymer chain have been studied by steady-state and time-resolved fluorescence techniques in toluene solution. The typical green emission from polyfluorenes containing 9-fluorenone moieties is only observed if the 9-fluorenone group is covalently attached to the polymer. Small-angle neutron scattering (SANS) measurements indicate that, independent of the 9-fluorenone fraction, all the studied copolymers adopt an open wormlike conformation. This prevalent 1-dimensional arrangement confirms that the green emission observed with polyfluorenes is not the result of excimer formation in the typical sandwich-like conformation. Analysis of time-resolved fluorescence decays by the maximum entropy method (MEM) collected at the polyfluorene emission (415 nm) and by global analysis of decays collected at 415 and 580 nm (the 9-fluorenone defect emission wavelength) clearly indicates two different time regimes in the population of the fluorenone defect: one occurring in the time interval of 10 to 30 ps and a second one occurring in the time range from 70 to 200 ps. While the slower process shows a linear dependence with the 9-fluorenone fraction, compatible with a hopping migration process along the polymer chain, the faster process does not show such a dependence and instead suggests a short-range Dexter mechanism. These findings are in agreement with our previous work where the presence of a faster component was suggested.

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“…Recently the osmotic coefficient of a synthetic stiff polyelectrolyte, a poly(para-phenylene), was measured in a salt-free environment [68,69]. We have compared this data to predictions of PB theory, and a local density functional theory which includes a correlation correction of the basis of a recently proposed Debye-Hückel-Hole-cavity theory (DHHC) [70], and simulational results within the cell model.…”

Section: Rodlike Polyelectrolytesmentioning

confidence: 99%

Computer Simulations of Charged Systems

Holm

Kremer

2001

Electrostatic Effects in Soft Matter and Biophysics

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Abstract. In this brief contribution to the Proceedings of the NATO-ASI on "Electrostatic Effects in Soft Matter and Biophysics" [1], which took place in Les Houches from Oct. 1-13, 2000, we summarize in short aspects of the simulations methods to study charged systems. After describing some basics of Monte Carlo and Molecular dynamics techniques, we describe a few methods to compute long range interactions in periodic systems. After a brief detour to mean-field models, we describe our results obtained for flexible polyelectrolytes in good and bad solvents. We follow with a description of the inhomogeneity of the counterion distribution around finite chains, and continue then with infinitely long, rodlike systems. The last part is devoted to the phenomenon of overcharging for colloidal particles and its explanation in terms of simple electrostatic arguments.

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Investigations of rodlike polyelectrolytes in solution by small-angle x-ray scattering

Cited by 28 publications

References 26 publications

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

Fast and Slow Time Regimes of Fluorescence Quenching in Conjugated Polyfluorene−Fluorenone Random Copolymers: The Role of Exciton Hopping and Dexter Transfer along the Polymer Backbone

Computer Simulations of Charged Systems

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