Interaction between the Water Soluble Poly{1,4-phenylene-[9,9-bis(4-phenoxy butylsulfonate)]fluorene-2,7-diyl} Copolymer and Ionic Surfactants Followed by Spectroscopic and Conductivity Measurements

Abstract

The interaction has been studied in aqueous solutions between a negatively charged conjugated polyelectrolyte poly{1,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer (PBS-PFP) and several cationic tetraalkylammonium surfactants with different structures (alkyl chain length, counterion, or double alkyl chain), with tetramethylammonium cations and with the anionic surfactant sodium dodecyl sulfate (SDS) by electronic absorption and emission spectroscopy and by conductivity measurements. The results are compared with those previously obtained on the interaction of the same polymer with the nonionic surfactant C12E5. The nature of the electrostatic or hydrophobic polymer-surfactant interactions leads to very different behavior. The polymer induces the aggregation with the cationic surfactants at concentrations well below the critical micelle concentration, while this is inhibited with the anionic SDS, as demonstrated from conductivity measurements. The interaction with cationic surfactants only shows a small dependence on alkyl chain length or counterion and is suggested to be dominated by electrostatic interactions. In contrast to previous studies with the nonionic C12E5, both the cationic and the anionic surfactants quench the PBS-PFP emission intensity, leading also to a decrease in the polymer emission lifetime. However, the interaction with these cationic surfactants leads to the appearance of a new emission band (approximately 525 nm), which may be due to energy hopping to defect sites due to the increase of PBS-PFP interchain interaction favored by charge neutralization of the anionic polymer by cationic surfactant and by hydrophobic interactions involving the surfactant alkyl chains, since the same green band is not observed by adding either tetramethylammonium hydroxide or chloride. This effect suggests that the cationic surfactants are changing the nature of PBS-PFP aggregates. The nature of the polymer and surfactant interactions can, thus, be used to control the spectroscopic and conductivity properties of the polymer, which may have implications in its applications.

Interactions between surfactants and {1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}

“…However, because of the rigid structure of PBS-PFP, we feel that the polymer-surfactant aggregates have a somewhat different structure from the pearl-necklace structure seen in more flexible polymer-surfactant systems. The origin of the new band at 525 nm is discussed in detail elsewhere [22]. These changes were accompanied by a decrease in the fluorescence lifetime observed at the main band and appearance of a second component with rather longer lifetime at 525 nm (Table 1).…”

“…Full details of synthesis and characterisation have been given elsewhere [20,22]. Cetyltrimethylammonium bromide (CTAB, Aldrich), sodium dodecyl sulfate (SDS, Aldrich), pentaethylene glycol monododecyl ether (C 12 E 5 , Fluka) and other reagents were of the purest grade available, and were used without further treatment.…”

Recent Applications of Conjugated Polyelectrolytes in Optoelectronic Devices

“…[53,54,59] Replacement of typical alkali or halide counterions in CPEs with organic ions is also known to modify chain packing. [39,56,[59][60][61] Such modifications may lead to interesting nanostructures in the solid state. [20,62] …”

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

“…15 Examples include polyelectrolytic PPV 16 and PF. 14,15,17 This technique can also be used to induce liquid crystallinity as shown for PPP 18,19 and poly-(p-pyridine). 20 Oxyethylene glycol-monoethers (C i E j ) 21,22 are archetypical surfactants widely used in fundamental phase studies of microemulsions, [23][24][25][26][27] block-co-polymers, 28 and micelles.…”