Surface and colloid properties of cyclic amides III. Surface activity and micellization of N-butyl-2-pyrrolidone in water

The aggregation and surface activity of N-butyl-2-pyrrolidone (BP) in water is investigated using surface tension, solubilization, fluorescence and NM R methods. The micelle point is high (similar to 1.0 M) as expected for the butyl chain length, and the aggregation number is approximately 5,with pre -association below the c.m.c. Despite the low aggregation number, the fluor escence data indicate that the interior of the aggregate is similar to pure liquid BP. The adsorption of BP at the solution/air interface goes to a ma ximum near the c.m.c., corresponding to an area of 45 +/- 1 Angstrom(2)/mol ecule.