Effects of block length and structure of surfactant on self-assembly and solution behavior of block ionomer complexes

Several new families of materials have been synthesized on the base of comp lexes 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 b romide (DODAB), and trioctylmethylammonium bromide (TMAB) were used as the surfactant components. In contrast to complexes of homopolymer PMA with the se surfactants, which precipitated from aqueous solutions, PEO-b-PMA comple xes formed stable dispersions with particle size in the range 100-200 nm. T he properties of these systems strongly depended on the lengths of the poly ion and nonionic blocks of PEO-b-PMA and the structure of the surfactant. I n particular, factors governing stability of these complexes in aqueous dis persion include lyophilizing effect of PEO block (increases with increase i n PEO chain length), repulsion of PEO chains (increases with decrease in PM A chain length), and packing parameter of the surfactant. Potential applica tions of these systems include drug delivery.