SURFACE-TENSION PROPERTIES OF AQUEOUS-SOLUTIONS OF DISULFUR BETAINE DERIVATIVES

The equilibrium and dynamic surface tensions of aqueous solutions of t wo newly synthesized surfactants relevant to wool dyeing were studied by means of the Wilhelmy plate and a bubble method. The surfactants lp ha),N(alpha)'-bis(N-dodecyl-N,N-dimethylglycine) cystine dimethyl este r dihydrochloride) and lpha),N(alpha)'-bis(N-dodecyl-N,N-dimethylglyci ne) cystamine dihydrochloride), are double-chain and bicationic in cha racter. Their CMCs and Langmuir adsorption equilibrium parameters were determined at 25-degrees-C. Both molecules are very efficient surfact ants. Their surface tensions equilibrate in time-scales ranging from s econds to hours (concentration c = 1000-2 muM). Their dynamic surface tensions under constant and pulsating area conditions indicate that th ere is a strong barrier to adsorption at the air-water interface. The presence of the micelles accelerates the net rate of adsorption, sugge sting fast micellar dissociation.