文摘
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 possesssulfonate or carboxylate groups on every phenyl ring, do not aggregate in water. The formation of aggregatesof PPE-SO3Na-L and PPE-CO2Na-L is demonstrated by comparing the concentration and temperaturedependence 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 thecharge density. In addition, the cationic surfactant, octadecyltrimethyl ammonium, is shown to dissociate thelow charge density polymer aggregates and to form supramolecular complexes with each of the differentpolyelectrolytes. Fluorescence correlation spectroscopy was applied to provide insight into the sizes ofaggregates under different solution conditions.