Size exclusion chromatography of cationic polyelectrolytes

Molecular weight distributions of the cationic polyelectrolyte poly(2-trimethylammonium ethyl methacrylate chloride) were determined via size exclusion chromatography (SEC) for a very broad molecular weight range ($\text{7.7 × 10}{}^3\text{?}\text{M}{}_{\mathrm{<mtext>w</mtext>}}\text{? 1.1 × 10}{}_7$). Non-size exclusion effects (ion inclusion, ion exclusion, adsorption) were controlled by special surface treatment of the stationary phase (DMAE-Fractosil^R, E. Merck) and by proper selection of the mobile phase. A non-linear effective molecular weight calibration procedure was applied to account for the high polydispersity of the polyelectrolyte standard polymers. $\text{M}{}_{\mathrm{w}}$ data from SEC experiments agree with results from light scattering, and the molecular weight distributions obtained from SEC and sedimentation velocity analysis compare well.