(147a) Aggregation Properties of Inorganic Electrolyte-Sds-Peg Ternary System

The aggregation properties of inorganic electrolyte-Sodium Dodecyl Sulfate (SDS)-Polyethyleneglycol (PEG) system was studied by means of surface tension measurement, fluorescence probe method, ultra-filtration and atomic absorption spectrometry in this paper. The results showed: two breakpoints (the first critical concentration c₁ , and the second critical concentration c₂) appeared at the surface tension and ultra-filtration curves of the systems in the presence of monovalent metal salt. It indicated that the soft cluster formed self-motivationally by PEG and the bound micelle of SDS with or without addition of alkali metal sulfate. c₁ decreased from 4.5 mmol.L^-1 to 0.81 mmol.L^-1 while c₂ increased slightly with increasing theconcentration of monovalent metal salt c_e. Therefore, the clusterization boundary of SDS-PEG extended. The specific saturation capacity of clusterization [G_∞] increased with the addition of alkali metal sulfate. Only one breakpoint (cmc) showed at the surface tension and ultra-filtration curves of the systems in the presence of bivalent metal inorganic electrolyte. The aggregation number of bound micelle (N_b) of the alkali metal sulfate salt- SDS-PEG system was measured using steady-state fluorescence technique. N_b increased with increasing SDS concentration(c) linearly when c was between c₁ and c₂ - (cmc-c₁), and increased monotonously withincreasing c_e, but decreased with increasing PEG concentration (c_p) because the number of combination points increased with c_p.