Solubilization of polyelectrolytic hairy-rod polyfluorene in aqueous solutions of nonionic surfactant

Knaapila, M; Almasy, L; Garamus, VM; Pearson, C; Pradhan, S; Petty, MC; Scherf, U; Burrows, HD; Monkman, AP

Abstract

We report on the solubilization, phase behavior, and self-organized colloidal structure of a ternary water-polyfluorene-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 (C12E5) at 20 degrees C. We show in particular how a high amount ( milligrams per milliliter) of polyfluorene can be solubilized by aqueous C12E5 via aggregate formation. The PBS-PFP and C12E5 concentrations of 0.31 x 10(-4)- 5 x 10(-4) M and 2.5 x 10(-4)- 75 x 10(-4) M, respectively, were used. Under the studied conditions, the photoluminescence (PL), surface tension, static contact angle, and (pi-A) isotherm measurements imply that D2O-PBS-PFP(C12E5)(x) realizes three phase regimes with an increasing molar ratio of surfactant over monomer unit (x). First, for x <= 0.5, the mixture is cloudy. In this regime polymer is only partially dissolved. Second, for 1 <= x <= 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 angstrom and mean length of similar to 900 angstrom. The ratio between contour length and persistence length is less than 3. Third, for x >= 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 similar to 0.015 angstrom(-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 C12E5 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.

Citation

Knaapila, M., Almasy, L., Garamus, V., Pearson, C., Pradhan, S., Petty, M., …Monkman, A. (2006). Solubilization of polyelectrolytic hairy-rod polyfluorene in aqueous solutions of nonionic surfactant. Journal of Physical Chemistry B (Soft Condensed Matter and Biophysical Chemistry), 110(21), 10248-10257. https://doi.org/10.1021/jp0560563

• Journal Article Type: Article
• Publication Date: 2006-06
• Journal: Journal of Physical Chemistry B (Soft Condensed Matter and Biophysical Chemistry)
• Print ISSN: 1520-6106
• Electronic ISSN: 1520-5207
• Publisher: American Chemical Society
• Volume: 110
• Issue: 21
• Pages: 10248-10257
• DOI: https://doi.org/10.1021/jp0560563
• Keywords: ANGLE NEUTRON-SCATTERING; DYNAMIC LIGHT-SCATTERING; POLYMER-LIKE MICELLES; X-RAY-SCATTERING; AMPHIPHILIC POLY(P-PHENYLENE); CONJUGATED POLYMER; WATER; PHASES; FILMS; FLUORESCENCE
• Public URL: https://durham-repository.worktribe.com/output/1569179