title: Charge density effects on the aggregation properties of poly(p-phenylene-ethynylene)-based anionic polyelectrolytes.
abstract: This work shows that low charge density poly(p-phenylene-ethynylene)s (PPE-SO3Na-L and PPE-CO2Na-L), which feature sulfonate and carboxylate groups on every other phenyl ring, form aggregates in water, whereas high charge density poly(p-phenylene-ethynylene)s (PPE-SO3Na-H and PPE-CO2Na-H), which possess sulfonate or carboxylate groups on every phenyl ring, do not aggregate in water. The formation of aggregates of PPE-SO3Na-L and PPE-CO2Na-L is demonstrated by comparing the concentration and temperature dependence of their steady-state spectra in water to that in DMSO, in which the two polymers do not aggregate. For the weak polyelectrolytes PPE-CO2Na-H and PPE-CO2Na-L, the solution pH was changed to vary the charge density. In addition, the cationic surfactant, octadecyltrimethyl ammonium, is shown to dissociate the low charge density polymer aggregates and to form supramolecular complexes with each of the different polyelectrolytes. Fluorescence correlation spectroscopy was applied to provide insight into the sizes of aggregates under different solution conditions.
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Mingyan
authors.initials: M
authors.lastname: Wu
authors.forename: Palwinder
authors.initials: P
authors.lastname: Kaur
authors.forename: Hongjun
authors.initials: H
authors.lastname: Yue
authors.forename: A M
authors.initials: AM
authors.lastname: Clemmens
authors.forename: David H
authors.initials: DH
authors.lastname: Waldeck
authors.forename: Cuihua
authors.initials: C
authors.lastname: Xue
authors.forename: Haiying
authors.initials: H
authors.lastname: Liu
mesh_terms: D000838:Anions; D002264:Carboxylic Acids / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013053:Spectrophotometry; D013451:Sulfonic Acids / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D000838:Anions; D002264:Carboxylic Acids; D004573:Electrolytes; D011108:Polymers; D013451:Sulfonic Acids; D013501:Surface-Active Agents; C473966:poly(phenylene ethynylene)