Session K1 - John H. Dillon Medal Symposium.
FOCUS session, Tuesday afternoon, March 04
Ballroom A, Austin Convention Center
To unravel factors that determine effective polyelectrolyte charge, the mobilities of various ionenes were measured by capillary electrophoresis in variable dielectric constant solvents. Ionenes derive charge from regularly spaced, quaternized nitrogens located in the chain backbone; synthetic methods allow direct control of this spacing. The study sheds light on two questions: (1) Does the dimensionless charge density parameter (predicted to collapse trends of dielectric constant, temperature, and charge spacing) accurately capture polyelectrolyte charge? (2) Does counterion condensation explain trends in mobility as the charge density parameter is varied? A negative response is returned for (1), since plotting mobility against dimensionless charge density does not generate a master curve. A less certain response is returned for (2), since mobility does not saturate with increasing dielectric constant but does with decreasing charge spacing. These responses are discussed in terms of preferential chain solvation, specific ion effects, the electrophoretic “relaxation” effect, etc.