Multicomponent Interdiffusion and Self-Diffusion of the Cationic Poly{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]fluorene-phenylene} Dibromide in a Dimethyl Sulfoxide + Water Solution

Abstract

The diffusion behavior of the conjugated polyelectrolyte poly{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]fluorene-phenylene} bromide (HTMA-PFP) with different molecular weights has been studied in dimethyl sulfoxide (DMSO) + water solutions. Samples of HTMA-PFP with various molecular weights were obtained by synthesis of poly[9,9-bis(6′-bromohexyl)fluorene-phenylene] via a Suzuki coupling reaction, characterized by size exclusion chromatography (SEC), and quaternized with trimethylamine. Multicomponent chemical interdiffusion coefficients (mutual diffusion coefficients) were determined for solutions of HTMA-PFP and DMSO in water using the Taylor dispersion method. The results suggest specific interactions between the DMSO and the polymer. In addition, these systems were studied by pulse-field gradient nuclear magnetic resonance spectroscopy (PFG-NMR), and the corresponding self-diffusion coefficients were obtained. These were modeled using the Kirkwood-Riseman model, and a good fit to the observed behavior was obtained using literature data for molecular dimensions.

Effects of Charge Density on Photophysics and Aggregation Behavior of Anionic Fluorene-Arylene Conjugated Polyelectrolytes

“…However, frequently CPEs are not present as isolated polymer chains, and they tend to aggregate in water [ 6 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ] and other specific solvents, such as methanol [ 28 ]. This reduces both solubility and fluorescence quantum yields, frequently leading to spectral shifts.…”

“…This reduces both solubility and fluorescence quantum yields, frequently leading to spectral shifts. This is a particularly serious problem with rigid rod polyelectrolytes, such as those that have a poly( p -phenylene) backbone, as well as the closely related fluorene-based polymers [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. For example, stirring the anionic alternating copolymer poly{[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl- alt -1,4-phenylene} (PBS-PFP) in water leads to the formation of a metastable dispersion of polymer clusters [ 24 , 26 ].…”

Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

“…Among CPEs, those involving fluorene-based systems offer the advantage of high fluorescence quantum yields and photostability, blue emission (suitable for energy transfer experiments), excellent thermal stability and high stability against oxidants, as well as good synthetic accessibility [ 19 , 20 ]. In addition, fluorene-based CPEs consist of a rigid hydrophobic polyfluorene backbone with flexible charged side chains, which induces interesting aggregation behaviour; this phenomenon directly affects their intrinsic fluorescence [ 21 – 24 ]. These properties have been used for studying interactions with biomolecules, such as proteins and DNA, allowing sensing platforms to be developed.…”

What conjugated polyelectrolytes tell us about aggregation in polyelectrolyte/surfactant systems

“…This is strongly supported by molecular dynamics simulations [37]. These poorly defined aggregates can be broken up by the addition of cosolvents [37], as confirmed by diffusion studies on closely related CPEs [38]. However, there are indications from fluorescence measurements that when cosolvents are used to break up these clusters there are still conjugated polyelectrolyte aggregates present at higher CPE concentrations [39].…”

“…Fig. 16b) shows the effect of the molecular weight in the molar electrical conductivity of the cationic poly-[ (9,9-bis(6'-N,N,N-trimethylammonium)hexyl)-fluorene phenylene] bromide (HTMA-PFP) with molar concentrations between 2.5 × 10 −6 and 4.0 × 10 −6 M, in terms of repeat units, in 4% DMSO-water solution [38]. It is possible to see that the HTMA with the highest molecular weight has the highest molar conductivity.…”