Abstract: The characteristics of bis-transition points in γ-lgc curves of surface active sodium alkylsulfates with water-soluble nonionic macromolecules such as PVP or PEG were studied, and saturation capacity of clusterization Γ_∞ and specific saturation capacity of clusterization [Γ_∞] of surfactant on macromolecule were calculated in accordance with the phenomena of pseudo double-plateau. [Γ_∞] of ROSO₃Na changes little with the chain length of both surfactant and macromolecule, as well as concentration of macromolecule. [Γ_∞]_reg are 8.96 and 3.74 mmol/L, or 0.394 m/n and 0.415 m/n for ROSO₃Na-PEG and ROSO₃Na-PVP respectively, which was obtained from regression of Γ_∞-c P. The results of t-test show that there is no significant difference between [Γ_∞]_reg and [Γ_∞]_exp, therefore, it is reasonable to express [Γ_∞], a supramolecular interaction parameter, as a constant for soft cluster of ROSO₃Na homologue with PEG or PVP respectively. It is deduced from the experimental results that the soft clusters are formed between normal pseudo-micelles of ROSO₃Na and macromolecules by supramolecular self-assembly force in which electrostatic interaction is dominant.

Key words: Specific saturation capacity of clusterization, Supramolecular self-assembly, Sodium alkylsulfate, Polyethyleneglycol(PEG), Polyvinylpyrrolidone(PVP)