Comparison of the Aggregation Behavior of 15 Polymeric and Monomeric Dipeptide Surfactants in Aqueous Solution

Abstract

The aggregation numbers of 15 dipeptide surfactants were estimated by use of fluorescence steady-state quenching techniques. Polymerization of the surfactants with γ radiation resulted in molecular micelles with a lower number of repeat units than the corresponding monomer aggregation numbers at the concentration of monomer used for polymerization in this study. In addition, the aggregation numbers of the monomers decreased with increasing size of the N-terminal R group of the dipeptide surfactants examined in this study. The aggregation behavior of the dipeptide surfactants was further investigated using proton NMR ( 1 H NMR) spectroscopy. The proton resonances due to NH and HR were measured above and below the critical micelle concentration of the surfactants. From the differences in proton chemical shifts of the monomeric dipeptide surfactants and aggregation numbers, a model for packing of the monomeric polar head is proposed.

Glycine-based polymeric surfactants with varied polar head group: I. Synthesis, characterization, and application in micellar electrokinetic chromatography

“…The A value of conventional micelles of SUG and SUCG was found to be significantly higher than the corresponding A value of micelle polymers, which is consistent with previous observations [36]. Furthermore, from the comparison of aggregation data for both SUG and SUCG surfactants, it can be argued that the carbamate group of SUCG surfactant series occupies a more compact space as compared to the amide group of SUG surfactants.…”

Use of poly(sodium oleyl‐L‐leucylvalinate) surfactant for the separation of chiral compounds in micellar electrokinetic chromatography

“…From the analytical ultracentrifugation measurements, the weight-average molecular weight for the polymeric surfactant poly-L-SOLV, was calculated and found to be 36 102 6 948. Using this weightaverage molecular weight, the aggregation number of the polymer poly-L-SOLV was determined to be 69 which correlates well with the polymer's aggregation number obtained by use of a Spex FluoroMax-3 spectrofluorimeter at room temperature using the fluorescence quenching method described by Billiot et al [39] (data not shown). Figure 4 illustrates the equilibrium distribution of poly-L-SOLV at 257C.…”

Recent progress in the use of soluble ionic polymers as pseudostationary phases for electrokinetic chromatography

“…Steady-state fluorescence quenching techniques were used to determine that the degree of polymerization for 15 polymeric chiral surfactants (18)(19)(20)(21)(22)(23)(24)(25) was one-half to one third of the aggregation number of the corresponding monomers (38-74) [38]. Five of the monomers had very high aggregation numbers (110-380), but the degree of polymerization of the corresponding polymers was not different from the other polymers.…”