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作者： Zifu Zhu and Wayne F. Reed

 

摘要：Certain hydrophobic dopants in surfactant solutions cause massive “supramicellar assemblies” (SAs) to form near the critical micelle concentration (CMC), characterized by a light-scattering peak (LSP). The SAs are large, dynamic, metastable nanostructures composed of surfactant/dopant. Here, a water-soluble polymer, poly(vinylpyrollidone) (PVP) suppresses SA formation in sodium dodecyl sulfate (SDS) solutions doped with dodecanol, but increases solution instability. Binding of SDS to PVP is stronger than micellization in the LSP regime, reflected in a decreased SA population and a dramatic reduction and inversion of Rayleigh scattering IR as [PVP] increases, since SAs are much more massive than PVP/SDS association structures. Above the LSP regime, SAs no longer exist and thus IR must re-establish its order, increasing with increasing [PVP]. This causes a cross-over in IR vs [SDS] with an “iso-scattering point,” where IR converges at a specific [SDS]. Weak LSP suppression is found using dodecyl tri­ethyl ammonium bromide (DTAB). Poly(ethylene oxide) (PEO)’s effect is small compared with PVP.

 

關鍵詞：light-scattering peak;supramicellar assemblies;surfactant–polymer interaction