Abstract: The ternary systems composed of some alkali metal(Li,Na and K) sulfate with sodium dodecyl sulfate(SDS) and polyethylene glycol(PEG) were studied by means of surface tension,steady-state fluorescence quenching and fluorescent molecule probe.The results show that the soft cluster formed spontaneously by PEG and the bound micelle of SDS in cases with or without alkali metal sulfate addition.The first critical concentration c₁ decreased while the second critical concentration c₂ increased slightly with ever-increasing level of alkali metal sulfate c_e,therefore,the clusterization boundary of SDS-PEG extended.The specific saturation capacity of clusterization increased with the addition of alkali metal sulfate and it even increased 40% when 50 mmol/L Li₂SO₄ was added to.The aggregation number of bound micelle N_b decreased linearly with the increase of PEG c_p while increased linearly as a function of c of SDS and increased monotonously as a function of c_e.Since the radius of alkali metal hydrated ion increased in the order as follows: K⁺(0.232(nm)<)Na⁺(0.276 nm)<Li⁺(0.34 nm),the capability of them to made N_b increased in the reversed order: K⁺>Na⁺>Li⁺.The characteristic fluorescence of the solubilized pyrene reveals that the polarity of bound(micelle) microenvironment decreased with the increase of the level of both c of SDS and c_e(Na₂SO₄),whereas(increases) with the increase of level of c_p.

Key words: Sodium dodecyl sulfate(SDS), Polyethylene glycol(PEG), Alkali metal sulfate, Bound micelle