The Action of Ligands in the Aggregation Process of Soft Colloidal Solution Monitored by Raman Spectroscopy

The formation of soft colloidal particles in solution and their aggregation process has been studied by Raman spectroscopy. The soft colloidal particles makes up at room temperature by the Sodium Dodecyl Sulfate (SDS) solution over the critical micellar concentration, while the micellar clustering is obtained adding in solution two different ligands: the Kryptofix 2.2.2 (K222) and crown ether 18-Crown-6 (18C6). The chosen ligands molecules are able to interact with the micellar interface inducing the cluster phase formation. Vibrational peaks fingerprints of the micelles formation have been observed and the evidences of the cluster-phase formation have been also achieved in the case of micelles solution doped with the two different macro-cyclic ligands. The ligands action is however different in the two cases as evinced by the careful analysis of the intensity and wavenumber evolution of characteristic Raman peaks at different ligants concentration values. The cluster phase formation and the effects induced on the hydration layer are analyzed showing how Raman spectroscopy is able to gain insight into self-assembly of soft colloidal particles.