Synergism in binary mixtures of surfactants: 9. N-alkyl-2-pyrrolidone-anionic mixtures

Abstract

The interactions of a series of N-alkylpyrrolidones—N-2-ethylhexyl-(C2,6P), N-octyl-(C8P), N-decyl-(C10P), and N-dodecyl-(C12P) 2-pyrrolidone—with sodium dodecanesulfonate (C12SNa) and commercial sodium linear dodecylbenzenesulfonate (LAS) were investigated. Molecular interaction parameters were consistent with those obtained previously on mixtures of moderately interacting zwitterionic and anionic surfactants. Mixtures of well-purified C8P and C12SNa showed synergism in surface or interfacial tension reduction efficiency at the aqueous/air, aqueous/Parafilm, aqueous/Teflon, and aqueous/hexadecane interfaces, both in pure water and in 0.1 M NaCl. C2,6P, C8P, and C10P exhibited synergism in surface tension reduction efficiency at the aqueous/air interface when mixed with LAS.