Adsorption properties of binary mixtures containing quaternary derivatives of lysosomotropic substances

The aim of presented work was to analyzed the adsorption properties of binary mixtures which containing quaternary derivatives of lysosomotropic substances (QDLS). The surfactants investigated were quaternary ammonium salts belong to the group of esterquats: fatty acids N,N-dimethylaminopropylesters methobromides (DMPM-n), fatty acids 1-dimethylamino-2-propyl methobromides (DMP2M-n). Two types of mixed systems were considered: DMPM-9 + DMP2M-9 and catanionic mixtures, as DMPM-9 + DBSNa. The equilibrium and dynamic surface tension data for these mixed systems were studied and interpreted. From dynamic surface tension data the micelle kinetics dissolution constant were determined. Moreover, the dynamic contact angle for investigated mixtures were measured at three model surfaces of different hydrophobocity: quartz, glass and paraffin. The obtained results indicated that the structure of monolayers formed in mixed systems is strongly affected by the composition of the bulk solution. Most of studied systems revealed synergistic effect in adsorption and wetting properties. Especially strong reduction of surface tension and value of cmc was observed for equimolar mixtures, in which the highly surface active complexes were probably created.