Aggregation and solvent interaction in nonionic surfactant systems with formamide

• The self-association and solvent interaction of some polyethylene glycol alkyl ether surfactants (CxEy) in fornamide have been studied via determinations of phase diagrams and NMR self-diffusion measurements. For C12E3 and C12 E4, small micelles but no liquid chrystalline phases form. Increasing the alkyl chain length to hexadecyl (C16E4, C16E6, and C16E8), mesophase formation occurs analogously to the corresponding aqueous system. No aggregate growth occurs in the micellar phase, neither at high temperatures and high surfactant concentrations nor when approaching the lower consolute temperature. The solvent diffusion was analyzed within the cell diffusion model, and a concentration-independent amount of 1-5 and probably not more than 3 formamide molecules was found to interact with each ethylene oxide group. Furthermore, the calculations indicated a ploymer-like state of the micellar headgroup shell, with a slight decrease of the formamide content therein at a raised temperature. In conclusion, the behaviour of CxEy/formamide systems is qualitatively similar to that of the corresponding aqueous sytem.

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)