title: Segregation in like-charged polyelectrolyte-surfactant mixtures can be precisely tuned via manipulation of the surfactant mass ratio.
abstract: In this study, we consider segregative phase separation in aqueous mixtures of quaternary ammonium surfactants didecyldimethylammonium chloride (DDQ) and alkyl (C12, 70%; C14 30%) dimethyl benzyl ammonium chloride (BAC) upon the addition of poly(diallyldimethylammonium) chloride (pDADMAC) as a function of both concentration and molecular weight. The nature of the surfactant type is dominant in determining the concentration at which separation into an upper essentially surfactant-rich phase and lower polyelectrolyte-rich phase is observed. However, for high-molecular-weight pDADMAC there is a clear indication of an additional depletion flocculation effect. When the BAC/DDQ ratio is tuned, the segregative phase separation point can be precisely controlled. We propose a phase separation mechanism for like-charged quaternary ammonium polyelectrolyte/surfactant/water mixtures induced by a reduction in the ionic atmosphere around the surfactant headgroup and possible ion pair formation. An additional polyelectrolyte-induced depletion flocculation effect was also observed.
authors: School of Chemistry, The University of Manchester, Manchester, UK.
authors: Peter W
authors: PW
authors: Wills
authors: Sonia G
authors: SG
authors: Lopez
authors: Jocelyn
authors: J
authors: Burr
authors: Pablo
authors: P
authors: Taboada
authors: Stephen G
authors: SG
authors: Yeates
mesh_terms: D001548:Benzalkonium Compounds / Q000737:chemistry*; D008970:Molecular Weight; D011095:Polyethylenes / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D001548:Benzalkonium Compounds; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; C027118:didecyldimethylammonium