Preparation and characterization of hydrosoluble, partially charged poly(styrenesulfonate)s of various controlled charge fractions and chain lengths

A series of hydrophobic polyelectrolytes with narrow molecular weight distributions and well-characterized fractions of charged monomers on the hydrophobic backbone has been prepared. These polymers are derived from the controlled sulfonation of a series of polystyrene standards with low polydispersity indices. We have used a gentle sulfonation method that had previously been designed for ionomers. Because we wished to push this reaction to higher sulfonation levels, a careful characterization of the product materials was necessary. The sulfonation level of each sample has been determined by NUR and elemental analysis, and the efficacy of NMR for this purpose has been demonstrated. Size exclusion chromatography (SEC) measurements in mixtures of acetonitrile and water have shown that under nearly all sulfonation conditions tested here the mass distribution of the resulting copolymer was the same as that of the parent standard material. The sulfonation reaction has been optimized and characterized according to the dependence of sulfonation level on reaction time, initial reagent concentrations, and molecular weight of precursor polystyrene.