Several new families of materials have been synthesized on the base of complexes of poly(ethylene oxide)-b-poly(sodium methacrylate) (PEO-b-PMA) with single-, double-, and triple-tail surfactants. Cetylpyridinium bromide (CPB), didodecyldimethylammonium bromide (DDDAB), dimethyldioctadecylammonium bromide (DODAB), and trioctylmethylammonium bromide (TMAB) were used as the surfactant components. In contrast to complexes of homopolymer PMA with these surfactants, which precipitated from aqueous solutions, PEO-b-PMA complexes formed stable dispersions with particle size in the range 100−200 nm. The properties of these systems strongly depended on the lengths of the polyion and nonionic blocks of PEO-b-PMA and the structure of the surfactant. In particular, factors governing stability of these complexes in aqueous dispersion include lyophilizing effect of PEO block (increases with increase in PEO chain length), repulsion of PEO chains (increases with decrease in PMA chain length), and packing parameter of the surfactant. Potential applications of these systems include drug delivery.

A systematic capillary electrophoresis study uncovered how polyelectrolyte effective charge density varies with backbone charge spacing and solvent dielectric constant. The study primarily focused on aliphatic ionenes, a special class of polyelectrolytes, which possess regularly spaced quaternary ammonium groups in the backbone. Complete ionization of functional units and good solvency in water or mixtures of water with lower dielectric constant solvents (methanol, acetonitrile) enabled continuous measurements of ionene effective charge density through the onset of counterion condensation. Ionenes with both uniform and alternating charge spacing were examined. As expected, effective charge density rose linearly with fixed charge density to a critical value, above which effective charge density remained constant. Deviating from expectation, the onset of condensation did not occur at a critical fixed charge density. Instead, condensation initiated at a constant critical Bjerrum length. The same onset condition was found for quaternized poly(vinyl pyridine)s. These experimental results suggest a new form of condensation, one driven by ion‐pairing of polyelectrolyte with counterions. In support of this hypothesis, the onset of condensation appeared to correlate with counterion size. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3616–3627, 2004