Interfacial Microgels Formed by Oppositely Charged Polyelectrolytes and Surfactants.Part 2.Influence of Surfactant Chain Length and Surfactant/Polymer Ratio

摘要

The adsorption and complexation of polystyrene sulfonate (a highly charged anionic poly electrolyte)and a series of cationic surfactants,alkyltrirnethy 1 ammonium bromide,C_nTAB,n-8-16,at the air-water interface has been studied by combining surface tension and ellipsometry measurements.We find that increasing the chain length of the surfactant from 8 to 10 carbons leads to a sharp increase in adsorption of PSS/C_nTAB complexes.When the surfactant tail length is further increased to 12 and 14 carbons,surface adsorption becomes less favored than macroscopic phase separation,resulting in a partial surface depletion.Furthermore,we find that when surface tensions are plotted against surfactant/monomer molar concentration ratio,all data collapse to a single curve.This result shows that the surfactant-polymer molar ratio,s/p,is a key parameter for tuning the surface activity of the complexes formed.