Dielectric Spectroscopy Investigation on the Interaction of Poly(diallyldimethylammonium chloride) with Sodium Decyl Sulfate in Aqueous Solution

The interaction between poly(diallyldimethylammonium chloride) (PDADMAC) and ionic surfactant sodium decyl sulfate (C10SO4Na) in aqueous solution was investigated by means of dielectric relaxation spectroscopy. To better understand the interaction, the dielectric behaviors of PDADMAC solution and C10SO4Na solution were also separately studied. For PDADMAC solution, two relaxations were observed, which were attributed to the polarization of loosely bound counterions along the directions parallel and perpendicular to the PDADMAC chain. For C10SO4Na solution, dielectric relaxation was observed at submicellar concentrations, which is ascribed to the counterion diffusion around premicelles. For the aqueous solutions of a PDADMAC/C10SO4Na mixture with different C10SO4Na concentrations, three surfactant concentration regions characterized by different dielectric behaviors were observed. The dielectric behavior in different regions was discussed through comparing it with that of PDADMAC solution and C10SO4Na solution. The possible interaction pattern and microstructure of the PDADMAC/C10SO4Na complex were proposed on the basis of the dielectric behavior.