jp7099527_si_002.pdf (281.57 kB)
Charge Density Effects on the Aggregation Properties of Poly(p-phenylene-ethynylene)-Based Anionic Polyelectrolytes
journal contribution
posted on 2008-03-20, 00:00 authored by Mingyan Wu, Palwinder Kaur, Hongjun Yue, A. M. Clemmens, David. H. Waldeck, Cuihua Xue, Haiying LiuThis 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.